Once we've copied some data for an iocb that is marked with IOCB_WAITQ,
we should no longer attempt to async lock a new page. Instead make sure
we return the copied amount, and let the caller retry, instead of
returning -EIOCBQUEUED for a new page.
This should only be possible with read-ahead disabled on the below
device, and multiple threads racing on the same file. Haven't been able
to reproduce on anything else.
Cc: stable@vger.kernel.org # v5.9
Fixes: 1a0a7853b9 ("mm: support async buffered reads in generic_file_buffered_read()")
Reported-by: Kent Overstreet <kent.overstreet@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Merge more updates from Andrew Morton:
"155 patches.
Subsystems affected by this patch series: mm (dax, debug, thp,
readahead, page-poison, util, memory-hotplug, zram, cleanups), misc,
core-kernel, get_maintainer, MAINTAINERS, lib, bitops, checkpatch,
binfmt, ramfs, autofs, nilfs, rapidio, panic, relay, kgdb, ubsan,
romfs, and fault-injection"
* emailed patches from Andrew Morton <akpm@linux-foundation.org>: (155 commits)
lib, uaccess: add failure injection to usercopy functions
lib, include/linux: add usercopy failure capability
ROMFS: support inode blocks calculation
ubsan: introduce CONFIG_UBSAN_LOCAL_BOUNDS for Clang
sched.h: drop in_ubsan field when UBSAN is in trap mode
scripts/gdb/tasks: add headers and improve spacing format
scripts/gdb/proc: add struct mount & struct super_block addr in lx-mounts command
kernel/relay.c: drop unneeded initialization
panic: dump registers on panic_on_warn
rapidio: fix the missed put_device() for rio_mport_add_riodev
rapidio: fix error handling path
nilfs2: fix some kernel-doc warnings for nilfs2
autofs: harden ioctl table
ramfs: fix nommu mmap with gaps in the page cache
mm: remove the now-unnecessary mmget_still_valid() hack
mm/gup: take mmap_lock in get_dump_page()
binfmt_elf, binfmt_elf_fdpic: use a VMA list snapshot
coredump: rework elf/elf_fdpic vma_dump_size() into common helper
coredump: refactor page range dumping into common helper
coredump: let dump_emit() bail out on short writes
...
Fix some broken comments including typo, grammar error and wrong function
name.
Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Link: https://lkml.kernel.org/r/20200913095456.54873-1-linmiaohe@huawei.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Fold ra_submit() into its last remaining user and pass the
readahead_control struct to both do_page_cache_ra() and
page_cache_sync_ra().
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Eric Biggers <ebiggers@google.com>
Link: https://lkml.kernel.org/r/20200903140844.14194-9-willy@infradead.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Patch series "Remove assumptions of THP size".
There are a number of places in the VM which assume that a THP is a PMD in
size. That's true today, and remains true after this patch series, but
this is a prerequisite for switching to arbitrary-sized THPs.
thp_nr_pages() still returns either HPAGE_PMD_NR or 1, but will be changed
later.
This patch (of 11):
page_cache_free_page() assumes THPs are PMD_SIZE; fix that assumption.
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Huang Ying <ying.huang@intel.com>
Link: https://lkml.kernel.org/r/20200908195539.25896-1-willy@infradead.org
Link: https://lkml.kernel.org/r/20200908195539.25896-2-willy@infradead.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
When a THP is removed from the page cache by reclaim, we replace it with a
shadow entry that occupies all slots of the XArray previously occupied by
the THP. If the user then accesses that page again, we only allocate a
single page, but storing it into the shadow entry replaces all entries
with that one page. That leads to bugs like
page dumped because: VM_BUG_ON_PAGE(page_to_pgoff(page) != offset)
------------[ cut here ]------------
kernel BUG at mm/filemap.c:2529!
https://bugzilla.kernel.org/show_bug.cgi?id=206569
This is hard to reproduce with mainline, but happens regularly with the
THP patchset (as so many more THPs are created). This solution is take
from the THP patchset. It splits the shadow entry into order-0 pieces at
the time that we bring a new page into cache.
Fixes: 99cb0dbd47 ("mm,thp: add read-only THP support for (non-shmem) FS")
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Song Liu <songliubraving@fb.com>
Cc: "Kirill A . Shutemov" <kirill@shutemov.name>
Cc: Qian Cai <cai@lca.pw>
Link: https://lkml.kernel.org/r/20200903183029.14930-4-willy@infradead.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Add redirect_neigh() BPF packet redirect helper, allowing to limit stack
traversal in common container configs and improving TCP back-pressure.
Daniel reports ~10Gbps => ~15Gbps single stream TCP performance gain.
Expand netlink policy support and improve policy export to user space.
(Ge)netlink core performs request validation according to declared
policies. Expand the expressiveness of those policies (min/max length
and bitmasks). Allow dumping policies for particular commands.
This is used for feature discovery by user space (instead of kernel
version parsing or trial and error).
Support IGMPv3/MLDv2 multicast listener discovery protocols in bridge.
Allow more than 255 IPv4 multicast interfaces.
Add support for Type of Service (ToS) reflection in SYN/SYN-ACK
packets of TCPv6.
In Multi-patch TCP (MPTCP) support concurrent transmission of data
on multiple subflows in a load balancing scenario. Enhance advertising
addresses via the RM_ADDR/ADD_ADDR options.
Support SMC-Dv2 version of SMC, which enables multi-subnet deployments.
Allow more calls to same peer in RxRPC.
Support two new Controller Area Network (CAN) protocols -
CAN-FD and ISO 15765-2:2016.
Add xfrm/IPsec compat layer, solving the 32bit user space on 64bit
kernel problem.
Add TC actions for implementing MPLS L2 VPNs.
Improve nexthop code - e.g. handle various corner cases when nexthop
objects are removed from groups better, skip unnecessary notifications
and make it easier to offload nexthops into HW by converting
to a blocking notifier.
Support adding and consuming TCP header options by BPF programs,
opening the doors for easy experimental and deployment-specific
TCP option use.
Reorganize TCP congestion control (CC) initialization to simplify life
of TCP CC implemented in BPF.
Add support for shipping BPF programs with the kernel and loading them
early on boot via the User Mode Driver mechanism, hence reusing all the
user space infra we have.
Support sleepable BPF programs, initially targeting LSM and tracing.
Add bpf_d_path() helper for returning full path for given 'struct path'.
Make bpf_tail_call compatible with bpf-to-bpf calls.
Allow BPF programs to call map_update_elem on sockmaps.
Add BPF Type Format (BTF) support for type and enum discovery, as
well as support for using BTF within the kernel itself (current use
is for pretty printing structures).
Support listing and getting information about bpf_links via the bpf
syscall.
Enhance kernel interfaces around NIC firmware update. Allow specifying
overwrite mask to control if settings etc. are reset during update;
report expected max time operation may take to users; support firmware
activation without machine reboot incl. limits of how much impact
reset may have (e.g. dropping link or not).
Extend ethtool configuration interface to report IEEE-standard
counters, to limit the need for per-vendor logic in user space.
Adopt or extend devlink use for debug, monitoring, fw update
in many drivers (dsa loop, ice, ionic, sja1105, qed, mlxsw,
mv88e6xxx, dpaa2-eth).
In mlxsw expose critical and emergency SFP module temperature alarms.
Refactor port buffer handling to make the defaults more suitable and
support setting these values explicitly via the DCBNL interface.
Add XDP support for Intel's igb driver.
Support offloading TC flower classification and filtering rules to
mscc_ocelot switches.
Add PTP support for Marvell Octeontx2 and PP2.2 hardware, as well as
fixed interval period pulse generator and one-step timestamping in
dpaa-eth.
Add support for various auth offloads in WiFi APs, e.g. SAE (WPA3)
offload.
Add Lynx PHY/PCS MDIO module, and convert various drivers which have
this HW to use it. Convert mvpp2 to split PCS.
Support Marvell Prestera 98DX3255 24-port switch ASICs, as well as
7-port Mediatek MT7531 IP.
Add initial support for QCA6390 and IPQ6018 in ath11k WiFi driver,
and wcn3680 support in wcn36xx.
Improve performance for packets which don't require much offloads
on recent Mellanox NICs by 20% by making multiple packets share
a descriptor entry.
Move chelsio inline crypto drivers (for TLS and IPsec) from the crypto
subtree to drivers/net. Move MDIO drivers out of the phy directory.
Clean up a lot of W=1 warnings, reportedly the actively developed
subsections of networking drivers should now build W=1 warning free.
Make sure drivers don't use in_interrupt() to dynamically adapt their
code. Convert tasklets to use new tasklet_setup API (sadly this
conversion is not yet complete).
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
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Merge tag 'net-next-5.10' of git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next
Pull networking updates from Jakub Kicinski:
- Add redirect_neigh() BPF packet redirect helper, allowing to limit
stack traversal in common container configs and improving TCP
back-pressure.
Daniel reports ~10Gbps => ~15Gbps single stream TCP performance gain.
- Expand netlink policy support and improve policy export to user
space. (Ge)netlink core performs request validation according to
declared policies. Expand the expressiveness of those policies
(min/max length and bitmasks). Allow dumping policies for particular
commands. This is used for feature discovery by user space (instead
of kernel version parsing or trial and error).
- Support IGMPv3/MLDv2 multicast listener discovery protocols in
bridge.
- Allow more than 255 IPv4 multicast interfaces.
- Add support for Type of Service (ToS) reflection in SYN/SYN-ACK
packets of TCPv6.
- In Multi-patch TCP (MPTCP) support concurrent transmission of data on
multiple subflows in a load balancing scenario. Enhance advertising
addresses via the RM_ADDR/ADD_ADDR options.
- Support SMC-Dv2 version of SMC, which enables multi-subnet
deployments.
- Allow more calls to same peer in RxRPC.
- Support two new Controller Area Network (CAN) protocols - CAN-FD and
ISO 15765-2:2016.
- Add xfrm/IPsec compat layer, solving the 32bit user space on 64bit
kernel problem.
- Add TC actions for implementing MPLS L2 VPNs.
- Improve nexthop code - e.g. handle various corner cases when nexthop
objects are removed from groups better, skip unnecessary
notifications and make it easier to offload nexthops into HW by
converting to a blocking notifier.
- Support adding and consuming TCP header options by BPF programs,
opening the doors for easy experimental and deployment-specific TCP
option use.
- Reorganize TCP congestion control (CC) initialization to simplify
life of TCP CC implemented in BPF.
- Add support for shipping BPF programs with the kernel and loading
them early on boot via the User Mode Driver mechanism, hence reusing
all the user space infra we have.
- Support sleepable BPF programs, initially targeting LSM and tracing.
- Add bpf_d_path() helper for returning full path for given 'struct
path'.
- Make bpf_tail_call compatible with bpf-to-bpf calls.
- Allow BPF programs to call map_update_elem on sockmaps.
- Add BPF Type Format (BTF) support for type and enum discovery, as
well as support for using BTF within the kernel itself (current use
is for pretty printing structures).
- Support listing and getting information about bpf_links via the bpf
syscall.
- Enhance kernel interfaces around NIC firmware update. Allow
specifying overwrite mask to control if settings etc. are reset
during update; report expected max time operation may take to users;
support firmware activation without machine reboot incl. limits of
how much impact reset may have (e.g. dropping link or not).
- Extend ethtool configuration interface to report IEEE-standard
counters, to limit the need for per-vendor logic in user space.
- Adopt or extend devlink use for debug, monitoring, fw update in many
drivers (dsa loop, ice, ionic, sja1105, qed, mlxsw, mv88e6xxx,
dpaa2-eth).
- In mlxsw expose critical and emergency SFP module temperature alarms.
Refactor port buffer handling to make the defaults more suitable and
support setting these values explicitly via the DCBNL interface.
- Add XDP support for Intel's igb driver.
- Support offloading TC flower classification and filtering rules to
mscc_ocelot switches.
- Add PTP support for Marvell Octeontx2 and PP2.2 hardware, as well as
fixed interval period pulse generator and one-step timestamping in
dpaa-eth.
- Add support for various auth offloads in WiFi APs, e.g. SAE (WPA3)
offload.
- Add Lynx PHY/PCS MDIO module, and convert various drivers which have
this HW to use it. Convert mvpp2 to split PCS.
- Support Marvell Prestera 98DX3255 24-port switch ASICs, as well as
7-port Mediatek MT7531 IP.
- Add initial support for QCA6390 and IPQ6018 in ath11k WiFi driver,
and wcn3680 support in wcn36xx.
- Improve performance for packets which don't require much offloads on
recent Mellanox NICs by 20% by making multiple packets share a
descriptor entry.
- Move chelsio inline crypto drivers (for TLS and IPsec) from the
crypto subtree to drivers/net. Move MDIO drivers out of the phy
directory.
- Clean up a lot of W=1 warnings, reportedly the actively developed
subsections of networking drivers should now build W=1 warning free.
- Make sure drivers don't use in_interrupt() to dynamically adapt their
code. Convert tasklets to use new tasklet_setup API (sadly this
conversion is not yet complete).
* tag 'net-next-5.10' of git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next: (2583 commits)
Revert "bpfilter: Fix build error with CONFIG_BPFILTER_UMH"
net, sockmap: Don't call bpf_prog_put() on NULL pointer
bpf, selftest: Fix flaky tcp_hdr_options test when adding addr to lo
bpf, sockmap: Add locking annotations to iterator
netfilter: nftables: allow re-computing sctp CRC-32C in 'payload' statements
net: fix pos incrementment in ipv6_route_seq_next
net/smc: fix invalid return code in smcd_new_buf_create()
net/smc: fix valid DMBE buffer sizes
net/smc: fix use-after-free of delayed events
bpfilter: Fix build error with CONFIG_BPFILTER_UMH
cxgb4/ch_ipsec: Replace the module name to ch_ipsec from chcr
net: sched: Fix suspicious RCU usage while accessing tcf_tunnel_info
bpf: Fix register equivalence tracking.
rxrpc: Fix loss of final ack on shutdown
rxrpc: Fix bundle counting for exclusive connections
netfilter: restore NF_INET_NUMHOOKS
ibmveth: Identify ingress large send packets.
ibmveth: Switch order of ibmveth_helper calls.
cxgb4: handle 4-tuple PEDIT to NAT mode translation
selftests: Add VRF route leaking tests
...
The generic write check helpers also don't have much to do with the page
cache, so move them to the vfs.
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
I would like to move all the generic helpers for the vfs remap range
functionality (aka clonerange and dedupe) into a separate file so that
they won't be scattered across the vfs and the mm subsystems. The
eventual goal is to be able to deselect remap_range.c if none of the
filesystems need that code, but the tricky part here is picking a
stable(ish) part of the merge window to rearrange code.
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
We dereference page->mapping and page->index directly after calling
find_subpage() and these fields are not valid for tail pages. While
commit 4101196b19 ("mm: page cache: store only head pages in i_pages")
introduced the call to find_subpage(), the problem existed prior to this;
I'm going to suggest all the way back to when THPs first existed.
The user-visible effects of this are almost negligible. To hit it, you
have to mmap a tmpfs file at an unaligned address and then it's only a
disabled optimisation causing page faults to happen more frequently than
they otherwise would.
Fix this by keeping both head and page pointers and checking the
appropriate one. We could use page_mapping() and page_to_index(), but
that's higher overhead.
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: William Kucharski <william.kucharski@oracle.com>
Link: https://lkml.kernel.org/r/20200911012532.24761-1-willy@infradead.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Add a new FGP_HEAD flag which avoids calling find_subpage() and add a
convenience wrapper for it.
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Huang Ying <ying.huang@intel.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Jani Nikula <jani.nikula@linux.intel.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Matthew Auld <matthew.auld@intel.com>
Cc: William Kucharski <william.kucharski@oracle.com>
Link: https://lkml.kernel.org/r/20200910183318.20139-9-willy@infradead.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Convert shmem_getpage_gfp() (the only remaining caller of
find_lock_entry()) to cope with a head page being returned instead of
the subpage for the index.
[willy@infradead.org: fix BUG()s]
Link https://lore.kernel.org/linux-mm/20200912032042.GA6583@casper.infradead.org/
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Huang Ying <ying.huang@intel.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Jani Nikula <jani.nikula@linux.intel.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Matthew Auld <matthew.auld@intel.com>
Cc: William Kucharski <william.kucharski@oracle.com>
Link: https://lkml.kernel.org/r/20200910183318.20139-8-willy@infradead.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
There are only four callers remaining of find_get_entry().
get_shadow_from_swap_cache() only wants to see shadow entries and doesn't
care about which page is returned. Push the find_subpage() call into
find_lock_entry(), find_get_incore_page() and pagecache_get_page().
[willy@infradead.org: fix oops]
Link: https://lkml.kernel.org/r/20200914112738.GM6583@casper.infradead.org
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Huang Ying <ying.huang@intel.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Jani Nikula <jani.nikula@linux.intel.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Matthew Auld <matthew.auld@intel.com>
Cc: William Kucharski <william.kucharski@oracle.com>
Link: https://lkml.kernel.org/r/20200910183318.20139-7-willy@infradead.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
i915 does not want to see value entries. Switch it to use
find_lock_page() instead, and remove the export of find_lock_entry().
Move find_lock_entry() and find_get_entry() to mm/internal.h to discourage
any future use.
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Huang Ying <ying.huang@intel.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Jani Nikula <jani.nikula@linux.intel.com>
Cc: Matthew Auld <matthew.auld@intel.com>
Cc: William Kucharski <william.kucharski@oracle.com>
Link: https://lkml.kernel.org/r/20200910183318.20139-6-willy@infradead.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Merge tag 'block-5.10-2020-10-12' of git://git.kernel.dk/linux-block
Pull block updates from Jens Axboe:
- Series of merge handling cleanups (Baolin, Christoph)
- Series of blk-throttle fixes and cleanups (Baolin)
- Series cleaning up BDI, seperating the block device from the
backing_dev_info (Christoph)
- Removal of bdget() as a generic API (Christoph)
- Removal of blkdev_get() as a generic API (Christoph)
- Cleanup of is-partition checks (Christoph)
- Series reworking disk revalidation (Christoph)
- Series cleaning up bio flags (Christoph)
- bio crypt fixes (Eric)
- IO stats inflight tweak (Gabriel)
- blk-mq tags fixes (Hannes)
- Buffer invalidation fixes (Jan)
- Allow soft limits for zone append (Johannes)
- Shared tag set improvements (John, Kashyap)
- Allow IOPRIO_CLASS_RT for CAP_SYS_NICE (Khazhismel)
- DM no-wait support (Mike, Konstantin)
- Request allocation improvements (Ming)
- Allow md/dm/bcache to use IO stat helpers (Song)
- Series improving blk-iocost (Tejun)
- Various cleanups (Geert, Damien, Danny, Julia, Tetsuo, Tian, Wang,
Xianting, Yang, Yufen, yangerkun)
* tag 'block-5.10-2020-10-12' of git://git.kernel.dk/linux-block: (191 commits)
block: fix uapi blkzoned.h comments
blk-mq: move cancel of hctx->run_work to the front of blk_exit_queue
blk-mq: get rid of the dead flush handle code path
block: get rid of unnecessary local variable
block: fix comment and add lockdep assert
blk-mq: use helper function to test hw stopped
block: use helper function to test queue register
block: remove redundant mq check
block: invoke blk_mq_exit_sched no matter whether have .exit_sched
percpu_ref: don't refer to ref->data if it isn't allocated
block: ratelimit handle_bad_sector() message
blk-throttle: Re-use the throtl_set_slice_end()
blk-throttle: Open code __throtl_de/enqueue_tg()
blk-throttle: Move service tree validation out of the throtl_rb_first()
blk-throttle: Move the list operation after list validation
blk-throttle: Fix IO hang for a corner case
blk-throttle: Avoid tracking latency if low limit is invalid
blk-throttle: Avoid getting the current time if tg->last_finish_time is 0
blk-throttle: Remove a meaningless parameter for throtl_downgrade_state()
block: Remove redundant 'return' statement
...
Rejecting non-native endian BTF overlapped with the addition
of support for it.
The rest were more simple overlapping changes, except the
renesas ravb binding update, which had to follow a file
move as well as a YAML conversion.
Signed-off-by: David S. Miller <davem@davemloft.net>
The async buffered reads feature is not working when readahead is
turned off. There are two things to concern:
- when doing retry in io_read, not only the IOCB_WAITQ flag but also
the IOCB_NOWAIT flag is still set, which makes it goes to would_block
phase in generic_file_buffered_read() and then return -EAGAIN. After
that, the io-wq thread work is queued, and later doing the async
reads in the old way.
- even if we remove IOCB_NOWAIT when doing retry, the feature is still
not running properly, since in generic_file_buffered_read() it goes to
lock_page_killable() after calling mapping->a_ops->readpage() to do
IO, and thus causing process to sleep.
Fixes: 1a0a7853b9 ("mm: support async buffered reads in generic_file_buffered_read()")
Fixes: 3b2a4439e0 ("io_uring: get rid of kiocb_wait_page_queue_init()")
Signed-off-by: Hao Xu <haoxu@linux.alibaba.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Replace the two negative flags that are always used together with a
single positive flag that indicates the writeback capability instead
of two related non-capabilities. Also remove the pointless wrappers
to just check the flag.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Jan Kara <jack@suse.cz>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Two minor conflicts:
1) net/ipv4/route.c, adding a new local variable while
moving another local variable and removing it's
initial assignment.
2) drivers/net/dsa/microchip/ksz9477.c, overlapping changes.
One pretty prints the port mode differently, whilst another
changes the driver to try and obtain the port mode from
the port node rather than the switch node.
Signed-off-by: David S. Miller <davem@davemloft.net>
Commit 2a9127fcf2 ("mm: rewrite wait_on_page_bit_common() logic") made
the page locking entirely fair, in that if a waiter came in while the
lock was held, the lock would be transferred to the lockers strictly in
order.
That was intended to finally get rid of the long-reported watchdog
failures that involved the page lock under extreme load, where a process
could end up waiting essentially forever, as other page lockers stole
the lock from under it.
It also improved some benchmarks, but it ended up causing huge
performance regressions on others, simply because fair lock behavior
doesn't end up giving out the lock as aggressively, causing better
worst-case latency, but potentially much worse average latencies and
throughput.
Instead of reverting that change entirely, this introduces a controlled
amount of unfairness, with a sysctl knob to tune it if somebody needs
to. But the default value should hopefully be good for any normal load,
allowing a few rounds of lock stealing, but enforcing the strict
ordering before the lock has been stolen too many times.
There is also a hint from Matthieu Baerts that the fair page coloring
may end up exposing an ABBA deadlock that is hidden by the usual
optimistic lock stealing, and while the unfairness doesn't fix the
fundamental issue (and I'm still looking at that), it avoids it in
practice.
The amount of unfairness can be modified by writing a new value to the
'sysctl_page_lock_unfairness' variable (default value of 5, exposed
through /proc/sys/vm/page_lock_unfairness), but that is hopefully
something we'd use mainly for debugging rather than being necessary for
any deep system tuning.
This whole issue has exposed just how critical the page lock can be, and
how contended it gets under certain locks. And the main contention
doesn't really seem to be anything related to IO (which was the origin
of this lock), but for things like just verifying that the page file
mapping is stable while faulting in the page into a page table.
Link: https://lore.kernel.org/linux-fsdevel/ed8442fd-6f54-dd84-cd4a-941e8b7ee603@MichaelLarabel.com/
Link: https://www.phoronix.com/scan.php?page=article&item=linux-50-59&num=1
Link: https://lore.kernel.org/linux-fsdevel/c560a38d-8313-51fb-b1ec-e904bd8836bc@tessares.net/
Reported-and-tested-by: Michael Larabel <Michael@michaellarabel.com>
Tested-by: Matthieu Baerts <matthieu.baerts@tessares.net>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Chris Mason <clm@fb.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
'static' and 'static noinline' function attributes make no guarantees that
gcc/clang won't optimize them. The compiler may decide to inline 'static'
function and in such case ALLOW_ERROR_INJECT becomes meaningless. The compiler
could have inlined __add_to_page_cache_locked() in one callsite and didn't
inline in another. In such case injecting errors into it would cause
unpredictable behavior. It's worse with 'static noinline' which won't be
inlined, but it still can be optimized. Like the compiler may decide to remove
one argument or constant propagate the value depending on the callsite.
To avoid such issues make sure that these functions are global noinline.
Fixes: af3b854492 ("mm/page_alloc.c: allow error injection")
Fixes: cfcbfb1382 ("mm/filemap.c: enable error injection at add_to_page_cache()")
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Link: https://lore.kernel.org/bpf/20200827220114.69225-2-alexei.starovoitov@gmail.com
struct file_ra_state ra.mmap_miss could be accessed concurrently during
page faults as noticed by KCSAN,
BUG: KCSAN: data-race in filemap_fault / filemap_map_pages
write to 0xffff9b1700a2c1b4 of 4 bytes by task 3292 on cpu 30:
filemap_fault+0x920/0xfc0
do_sync_mmap_readahead at mm/filemap.c:2384
(inlined by) filemap_fault at mm/filemap.c:2486
__xfs_filemap_fault+0x112/0x3e0 [xfs]
xfs_filemap_fault+0x74/0x90 [xfs]
__do_fault+0x9e/0x220
do_fault+0x4a0/0x920
__handle_mm_fault+0xc69/0xd00
handle_mm_fault+0xfc/0x2f0
do_page_fault+0x263/0x6f9
page_fault+0x34/0x40
read to 0xffff9b1700a2c1b4 of 4 bytes by task 3313 on cpu 32:
filemap_map_pages+0xc2e/0xd80
filemap_map_pages at mm/filemap.c:2625
do_fault+0x3da/0x920
__handle_mm_fault+0xc69/0xd00
handle_mm_fault+0xfc/0x2f0
do_page_fault+0x263/0x6f9
page_fault+0x34/0x40
Reported by Kernel Concurrency Sanitizer on:
CPU: 32 PID: 3313 Comm: systemd-udevd Tainted: G W L 5.5.0-next-20200210+ #1
Hardware name: HPE ProLiant DL385 Gen10/ProLiant DL385 Gen10, BIOS A40 07/10/2019
ra.mmap_miss is used to contribute the readahead decisions, a data race
could be undesirable. Both the read and write is only under non-exclusive
mmap_sem, two concurrent writers could even underflow the counter. Fix
the underflow by writing to a local variable before committing a final
store to ra.mmap_miss given a small inaccuracy of the counter should be
acceptable.
Signed-off-by: Kirill A. Shutemov <kirill@shutemov.name>
Signed-off-by: Qian Cai <cai@lca.pw>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Tested-by: Qian Cai <cai@lca.pw>
Reviewed-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Marco Elver <elver@google.com>
Link: http://lkml.kernel.org/r/20200211030134.1847-1-cai@lca.pw
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The thp prefix is more frequently used than hpage and we should be
consistent between the various functions.
[akpm@linux-foundation.org: fix mm/migrate.c]
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: William Kucharski <william.kucharski@oracle.com>
Reviewed-by: Zi Yan <ziy@nvidia.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Link: http://lkml.kernel.org/r/20200629151959.15779-6-willy@infradead.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Drop the repeated word "the".
Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Zi Yan <ziy@nvidia.com>
Link: http://lkml.kernel.org/r/20200801173822.14973-3-rdunlap@infradead.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
FGP_{WRITE|NOFS|NOWAIT} were missed in pagecache_get_page's kerneldoc
comment.
Signed-off-by: Yang Shi <yang.shi@linux.alibaba.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Gang Deng <gavin.dg@linux.alibaba.com>
Cc: Shakeel Butt <shakeelb@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Rik van Riel <riel@surriel.com>
Link: http://lkml.kernel.org/r/1593031747-4249-1-git-send-email-yang.shi@linux.alibaba.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Since commit bbddabe2e4 ("mm: filemap: only do access activations on
reads"), mark_page_accessed() is called for reads only. But the idle flag
is cleared by mark_page_accessed() so the idle flag won't get cleared if
the page is write accessed only.
Basically idle page tracking is used to estimate workingset size of
workload, noticeable size of workingset might be missed if the idle flag
is not maintained correctly.
It seems good enough to just clear idle flag for write operations.
Fixes: bbddabe2e4 ("mm: filemap: only do access activations on reads")
Reported-by: Gang Deng <gavin.dg@linux.alibaba.com>
Signed-off-by: Yang Shi <yang.shi@linux.alibaba.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Shakeel Butt <shakeelb@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Rik van Riel <riel@surriel.com>
Link: http://lkml.kernel.org/r/1593020612-13051-1-git-send-email-yang.shi@linux.alibaba.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Merge tag 'for-5.9/io_uring-20200802' of git://git.kernel.dk/linux-block
Pull io_uring updates from Jens Axboe:
"Lots of cleanups in here, hardening the code and/or making it easier
to read and fixing bugs, but a core feature/change too adding support
for real async buffered reads. With the latter in place, we just need
buffered write async support and we're done relying on kthreads for
the fast path. In detail:
- Cleanup how memory accounting is done on ring setup/free (Bijan)
- sq array offset calculation fixup (Dmitry)
- Consistently handle blocking off O_DIRECT submission path (me)
- Support proper async buffered reads, instead of relying on kthread
offload for that. This uses the page waitqueue to drive retries
from task_work, like we handle poll based retry. (me)
- IO completion optimizations (me)
- Fix race with accounting and ring fd install (me)
- Support EPOLLEXCLUSIVE (Jiufei)
- Get rid of the io_kiocb unionizing, made possible by shrinking
other bits (Pavel)
- Completion side cleanups (Pavel)
- Cleanup REQ_F_ flags handling, and kill off many of them (Pavel)
- Request environment grabbing cleanups (Pavel)
- File and socket read/write cleanups (Pavel)
- Improve kiocb_set_rw_flags() (Pavel)
- Tons of fixes and cleanups (Pavel)
- IORING_SQ_NEED_WAKEUP clear fix (Xiaoguang)"
* tag 'for-5.9/io_uring-20200802' of git://git.kernel.dk/linux-block: (127 commits)
io_uring: flip if handling after io_setup_async_rw
fs: optimise kiocb_set_rw_flags()
io_uring: don't touch 'ctx' after installing file descriptor
io_uring: get rid of atomic FAA for cq_timeouts
io_uring: consolidate *_check_overflow accounting
io_uring: fix stalled deferred requests
io_uring: fix racy overflow count reporting
io_uring: deduplicate __io_complete_rw()
io_uring: de-unionise io_kiocb
io-wq: update hash bits
io_uring: fix missing io_queue_linked_timeout()
io_uring: mark ->work uninitialised after cleanup
io_uring: deduplicate io_grab_files() calls
io_uring: don't do opcode prep twice
io_uring: clear IORING_SQ_NEED_WAKEUP after executing task works
io_uring: batch put_task_struct()
tasks: add put_task_struct_many()
io_uring: return locked and pinned page accounting
io_uring: don't miscount pinned memory
io_uring: don't open-code recv kbuf managment
...
It turns out that wait_on_page_bit_common() had several problems,
ranging from just unfair behavioe due to re-queueing at the end of the
wait queue when re-trying, and an outright bug that could result in
missed wakeups (but probably never happened in practice).
This rewrites the whole logic to avoid both issues, by simply moving the
logic to check (and possibly take) the bit lock into the wakeup path
instead.
That makes everything much more straightforward, and means that we never
need to re-queue the wait entry: if we get woken up, we'll be notified
through WQ_FLAG_WOKEN, and the wait queue entry will have been removed,
and everything will have been done for us.
Link: https://lore.kernel.org/lkml/CAHk-=wjJA2Z3kUFb-5s=6+n0qbTs8ELqKFt9B3pH85a8fGD73w@mail.gmail.com/
Link: https://lore.kernel.org/lkml/alpine.LSU.2.11.2007221359450.1017@eggly.anvils/
Reported-by: Oleg Nesterov <oleg@redhat.com>
Reported-by: Hugh Dickins <hughd@google.com>
Cc: Michal Hocko <mhocko@suse.com>
Reviewed-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Add an IOCB_NOIO flag that indicates to generic_file_read_iter that it
shouldn't trigger any filesystem I/O for the actual request or for
readahead. This allows to do tentative reads out of the page cache as
some filesystems allow, and to take the appropriate locks and retry the
reads only if the requested pages are not cached.
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
Use the async page locking infrastructure, if IOCB_WAITQ is set in the
passed in iocb. The caller must expect an -EIOCBQUEUED return value,
which means that IO is started but not done yet. This is similar to how
O_DIRECT signals the same operation. Once the callback is received by
the caller for IO completion, the caller must retry the operation.
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Normally waiting for a page to become unlocked, or locking the page,
requires waiting for IO to complete. Add support for lock_page_async()
and wait_on_page_locked_async(), which are callback based instead. This
allows a caller to get notified when a page becomes unlocked, rather
than wait for it.
We add a new iocb field, ki_waitq, to pass in the necessary data for this
to happen. We can unionize this with ki_cookie, since that is only used
for polled IO. Polled IO can never co-exist with async callbacks, as it is
(by definition) polled completions. struct wait_page_key is made public,
and we define struct wait_page_async as the interface between the caller
and the core.
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
No functional changes in this patch, just in preparation for allowing
more callers.
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
The read-ahead shouldn't block, so allow it to be done even if
IOCB_NOWAIT is set in the kiocb.
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
There is a typo in comment, fix it.
Signed-off-by: Ethon Paul <ethp@qq.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Ralph Campbell <rcampbell@nvidia.com>
Link: http://lkml.kernel.org/r/20200411065141.15936-1-ethp@qq.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Swapin faults were the last event to charge pages after they had already
been put on the LRU list. Now that we charge directly on swapin, the
lrucare portion of the charge code is unused.
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Alex Shi <alex.shi@linux.alibaba.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: "Kirill A. Shutemov" <kirill@shutemov.name>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Roman Gushchin <guro@fb.com>
Cc: Balbir Singh <bsingharora@gmail.com>
Cc: Shakeel Butt <shakeelb@google.com>
Link: http://lkml.kernel.org/r/20200508183105.225460-19-hannes@cmpxchg.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
With the page->mapping requirement gone from memcg, we can charge anon and
file-thp pages in one single step, right after they're allocated.
This removes two out of three API calls - especially the tricky commit
step that needed to happen at just the right time between when the page is
"set up" and when it's "published" - somewhat vague and fluid concepts
that varied by page type. All we need is a freshly allocated page and a
memcg context to charge.
v2: prevent double charges on pre-allocated hugepages in khugepaged
[hannes@cmpxchg.org: Fix crash - *hpage could be ERR_PTR instead of NULL]
Link: http://lkml.kernel.org/r/20200512215813.GA487759@cmpxchg.org
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Alex Shi <alex.shi@linux.alibaba.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: "Kirill A. Shutemov" <kirill@shutemov.name>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Roman Gushchin <guro@fb.com>
Cc: Shakeel Butt <shakeelb@google.com>
Cc: Balbir Singh <bsingharora@gmail.com>
Cc: Qian Cai <cai@lca.pw>
Link: http://lkml.kernel.org/r/20200508183105.225460-13-hannes@cmpxchg.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Memcg maintains private MEMCG_CACHE and NR_SHMEM counters. This
divergence from the generic VM accounting means unnecessary code overhead,
and creates a dependency for memcg that page->mapping is set up at the
time of charging, so that page types can be told apart.
Convert the generic accounting sites to mod_lruvec_page_state and friends
to maintain the per-cgroup vmstat counters of NR_FILE_PAGES and NR_SHMEM.
The page is already locked in these places, so page->mem_cgroup is stable;
we only need minimal tweaks of two mem_cgroup_migrate() calls to ensure
it's set up in time.
Then replace MEMCG_CACHE with NR_FILE_PAGES and delete the private
NR_SHMEM accounting sites.
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Alex Shi <alex.shi@linux.alibaba.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: "Kirill A. Shutemov" <kirill@shutemov.name>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Roman Gushchin <guro@fb.com>
Cc: Shakeel Butt <shakeelb@google.com>
Cc: Balbir Singh <bsingharora@gmail.com>
Link: http://lkml.kernel.org/r/20200508183105.225460-10-hannes@cmpxchg.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The try/commit/cancel protocol that memcg uses dates back to when pages
used to be uncharged upon removal from the page cache, and thus couldn't
be committed before the insertion had succeeded. Nowadays, pages are
uncharged when they are physically freed; it doesn't matter whether the
insertion was successful or not. For the page cache, the transaction
dance has become unnecessary.
Introduce a mem_cgroup_charge() function that simply charges a newly
allocated page to a cgroup and sets up page->mem_cgroup in one single
step. If the insertion fails, the caller doesn't have to do anything but
free/put the page.
Then switch the page cache over to this new API.
Subsequent patches will also convert anon pages, but it needs a bit more
prep work. Right now, memcg depends on page->mapping being already set up
at the time of charging, so that it can maintain its own MEMCG_CACHE and
MEMCG_RSS counters. For anon, page->mapping is set under the same pte
lock under which the page is publishd, so a single charge point that can
block doesn't work there just yet.
The following prep patches will replace the private memcg counters with
the generic vmstat counters, thus removing the page->mapping dependency,
then complete the transition to the new single-point charge API and delete
the old transactional scheme.
v2: leave shmem swapcache when charging fails to avoid double IO (Joonsoo)
v3: rebase on preceeding shmem simplification patch
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Alex Shi <alex.shi@linux.alibaba.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: "Kirill A. Shutemov" <kirill@shutemov.name>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Roman Gushchin <guro@fb.com>
Cc: Shakeel Butt <shakeelb@google.com>
Cc: Balbir Singh <bsingharora@gmail.com>
Link: http://lkml.kernel.org/r/20200508183105.225460-6-hannes@cmpxchg.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The memcg charging API carries a boolean @compound parameter that tells
whether the page we're dealing with is a hugepage.
mem_cgroup_commit_charge() has another boolean @lrucare that indicates
whether the page needs LRU locking or not while charging. The majority of
callsites know those parameters at compile time, which results in a lot of
naked "false, false" argument lists. This makes for cryptic code and is a
breeding ground for subtle mistakes.
Thankfully, the huge page state can be inferred from the page itself and
doesn't need to be passed along. This is safe because charging completes
before the page is published and somebody may split it.
Simplify the callsites by removing @compound, and let memcg infer the
state by using hpage_nr_pages() unconditionally. That function does
PageTransHuge() to identify huge pages, which also helpfully asserts that
nobody passes in tail pages by accident.
The following patches will introduce a new charging API, best not to carry
over unnecessary weight.
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Alex Shi <alex.shi@linux.alibaba.com>
Reviewed-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Reviewed-by: Shakeel Butt <shakeelb@google.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: "Kirill A. Shutemov" <kirill@shutemov.name>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Roman Gushchin <guro@fb.com>
Cc: Balbir Singh <bsingharora@gmail.com>
Link: http://lkml.kernel.org/r/20200508183105.225460-4-hannes@cmpxchg.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Patch series "mm: memcontrol: charge swapin pages on instantiation", v2.
This patch series reworks memcg to charge swapin pages directly at
swapin time, rather than at fault time, which may be much later, or
not happen at all.
Changes in version 2:
- prevent double charges on pre-allocated hugepages in khugepaged
- leave shmem swapcache when charging fails to avoid double IO (Joonsoo)
- fix temporary accounting bug by switching rmap<->commit (Joonsoo)
- fix double swap charge bug in cgroup1/cgroup2 code gating
- simplify swapin error checking (Joonsoo)
- mm: memcontrol: document the new swap control behavior (Alex)
- review tags
The delayed swapin charging scheme we have right now causes problems:
- Alex's per-cgroup lru_lock patches rely on pages that have been
isolated from the LRU to have a stable page->mem_cgroup; otherwise
the lock may change underneath him. Swapcache pages are charged only
after they are added to the LRU, and charging doesn't follow the LRU
isolation protocol.
- Joonsoo's anon workingset patches need a suitable LRU at the time
the page enters the swap cache and displaces the non-resident
info. But the correct LRU is only available after charging.
- It's a containment hole / DoS vector. Users can trigger arbitrarily
large swap readahead using MADV_WILLNEED. The memory is never
charged unless somebody actually touches it.
- It complicates the page->mem_cgroup stabilization rules
In order to charge pages directly at swapin time, the memcg code base
needs to be prepared, and several overdue cleanups become a necessity:
To charge pages at swapin time, we need to always have cgroup
ownership tracking of swap records. We also cannot rely on
page->mapping to tell apart page types at charge time, because that's
only set up during a page fault.
To eliminate the page->mapping dependency, memcg needs to ditch its
private page type counters (MEMCG_CACHE, MEMCG_RSS, NR_SHMEM) in favor
of the generic vmstat counters and accounting sites, such as
NR_FILE_PAGES, NR_ANON_MAPPED etc.
To switch to generic vmstat counters, the charge sequence must be
adjusted such that page->mem_cgroup is set up by the time these
counters are modified.
The series is structured as follows:
1. Bug fixes
2. Decoupling charging from rmap
3. Swap controller integration into memcg
4. Direct swapin charging
This patch (of 19):
When replacing one page with another one in the cache, we have to decrease
the file count of the old page's NUMA node and increase the one of the new
NUMA node, otherwise the old node leaks the count and the new node
eventually underflows its counter.
Fixes: 74d609585d ("page cache: Add and replace pages using the XArray")
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Alex Shi <alex.shi@linux.alibaba.com>
Reviewed-by: Shakeel Butt <shakeelb@google.com>
Reviewed-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Reviewed-by: Balbir Singh <bsingharora@gmail.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: "Kirill A. Shutemov" <kirill@shutemov.name>
Cc: Roman Gushchin <guro@fb.com>
Link: http://lkml.kernel.org/r/20200508183105.225460-1-hannes@cmpxchg.org
Link: http://lkml.kernel.org/r/20200508183105.225460-2-hannes@cmpxchg.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Merge tag 'for-5.8-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux
Pull btrfs updates from David Sterba:
"Highlights:
- speedup dead root detection during orphan cleanup, eg. when there
are many deleted subvolumes waiting to be cleaned, the trees are
now looked up in radix tree instead of a O(N^2) search
- snapshot creation with inherited qgroup will mark the qgroup
inconsistent, requires a rescan
- send will emit file capabilities after chown, this produces a
stream that does not need postprocessing to set the capabilities
again
- direct io ported to iomap infrastructure, cleaned up and simplified
code, notably removing last use of struct buffer_head in btrfs code
Core changes:
- factor out backreference iteration, to be used by ordinary
backreferences and relocation code
- improved global block reserve utilization
* better logic to serialize requests
* increased maximum available for unlink
* improved handling on large pages (64K)
- direct io cleanups and fixes
* simplify layering, where cloned bios were unnecessarily created
for some cases
* error handling fixes (submit, endio)
* remove repair worker thread, used to avoid deadlocks during
repair
- refactored block group reading code, preparatory work for new type
of block group storage that should improve mount time on large
filesystems
Cleanups:
- cleaned up (and slightly sped up) set/get helpers for metadata data
structure members
- root bit REF_COWS got renamed to SHAREABLE to reflect the that the
blocks of the tree get shared either among subvolumes or with the
relocation trees
Fixes:
- when subvolume deletion fails due to ENOSPC, the filesystem is not
turned read-only
- device scan deals with devices from other filesystems that changed
ownership due to overwrite (mkfs)
- fix a race between scrub and block group removal/allocation
- fix long standing bug of a runaway balance operation, printing the
same line to the syslog, caused by a stale status bit on a reloc
tree that prevented progress
- fix corrupt log due to concurrent fsync of inodes with shared
extents
- fix space underflow for NODATACOW and buffered writes when it for
some reason needs to fallback to COW mode"
* tag 'for-5.8-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux: (133 commits)
btrfs: fix space_info bytes_may_use underflow during space cache writeout
btrfs: fix space_info bytes_may_use underflow after nocow buffered write
btrfs: fix wrong file range cleanup after an error filling dealloc range
btrfs: remove redundant local variable in read_block_for_search
btrfs: open code key_search
btrfs: split btrfs_direct_IO to read and write part
btrfs: remove BTRFS_INODE_READDIO_NEED_LOCK
fs: remove dio_end_io()
btrfs: switch to iomap_dio_rw() for dio
iomap: remove lockdep_assert_held()
iomap: add a filesystem hook for direct I/O bio submission
fs: export generic_file_buffered_read()
btrfs: turn space cache writeout failure messages into debug messages
btrfs: include error on messages about failure to write space/inode caches
btrfs: remove useless 'fail_unlock' label from btrfs_csum_file_blocks()
btrfs: do not ignore error from btrfs_next_leaf() when inserting checksums
btrfs: make checksum item extension more efficient
btrfs: fix corrupt log due to concurrent fsync of inodes with shared extents
btrfs: unexport btrfs_compress_set_level()
btrfs: simplify iget helpers
...
We no longer return 0 here and the comment doesn't tell us anything that
we don't already know (SIGBUS is a pretty good indicator that things
didn't work out).
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: William Kucharski <william.kucharski@oracle.com>
Link: http://lkml.kernel.org/r/20200529123243.20640-1-willy@infradead.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Export generic_file_buffered_read() to be used to supplement incomplete
direct reads.
Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Goldwyn Rodrigues <rgoldwyn@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Yang Shi writes:
Currently, when truncating a shmem file, if the range is partly in a THP
(start or end is in the middle of THP), the pages actually will just get
cleared rather than being freed, unless the range covers the whole THP.
Even though all the subpages are truncated (randomly or sequentially), the
THP may still be kept in page cache.
This might be fine for some usecases which prefer preserving THP, but
balloon inflation is handled in base page size. So when using shmem THP
as memory backend, QEMU inflation actually doesn't work as expected since
it doesn't free memory. But the inflation usecase really needs to get the
memory freed. (Anonymous THP will also not get freed right away, but will
be freed eventually when all subpages are unmapped: whereas shmem THP
still stays in page cache.)
Split THP right away when doing partial hole punch, and if split fails
just clear the page so that read of the punched area will return zeroes.
Hugh Dickins adds:
Our earlier "team of pages" huge tmpfs implementation worked in the way
that Yang Shi proposes; and we have been using this patch to continue to
split the huge page when hole-punched or truncated, since converting over
to the compound page implementation. Although huge tmpfs gives out huge
pages when available, if the user specifically asks to truncate or punch a
hole (perhaps to free memory, perhaps to reduce the memcg charge), then
the filesystem should do so as best it can, splitting the huge page.
That is not always possible: any additional reference to the huge page
prevents split_huge_page() from succeeding, so the result can be flaky.
But in practice it works successfully enough that we've not seen any
problem from that.
Add shmem_punch_compound() to encapsulate the decision of when a split is
needed, and doing the split if so. Using this simplifies the flow in
shmem_undo_range(); and the first (trylock) pass does not need to do any
page clearing on failure, because the second pass will either succeed or
do that clearing. Following the example of zero_user_segment() when
clearing a partial page, add flush_dcache_page() and set_page_dirty() when
clearing a hole - though I'm not certain that either is needed.
But: split_huge_page() would be sure to fail if shmem_undo_range()'s
pagevec holds further references to the huge page. The easiest way to fix
that is for find_get_entries() to return early, as soon as it has put one
compound head or tail into the pagevec. At first this felt like a hack;
but on examination, this convention better suits all its callers - or will
do, if the slight one-page-per-pagevec slowdown in shmem_unlock_mapping()
and shmem_seek_hole_data() is transformed into a 512-page-per-pagevec
speedup by checking for compound pages there.
Signed-off-by: Hugh Dickins <hughd@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Yang Shi <yang.shi@linux.alibaba.com>
Cc: Alexander Duyck <alexander.duyck@gmail.com>
Cc: "Michael S. Tsirkin" <mst@redhat.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Link: http://lkml.kernel.org/r/alpine.LSU.2.11.2002261959020.10801@eggly.anvils
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The idea comes from a discussion between Linus and Andrea [1].
Before this patch we only allow a page fault to retry once. We achieved
this by clearing the FAULT_FLAG_ALLOW_RETRY flag when doing
handle_mm_fault() the second time. This was majorly used to avoid
unexpected starvation of the system by looping over forever to handle the
page fault on a single page. However that should hardly happen, and after
all for each code path to return a VM_FAULT_RETRY we'll first wait for a
condition (during which time we should possibly yield the cpu) to happen
before VM_FAULT_RETRY is really returned.
This patch removes the restriction by keeping the FAULT_FLAG_ALLOW_RETRY
flag when we receive VM_FAULT_RETRY. It means that the page fault handler
now can retry the page fault for multiple times if necessary without the
need to generate another page fault event. Meanwhile we still keep the
FAULT_FLAG_TRIED flag so page fault handler can still identify whether a
page fault is the first attempt or not.
Then we'll have these combinations of fault flags (only considering
ALLOW_RETRY flag and TRIED flag):
- ALLOW_RETRY and !TRIED: this means the page fault allows to
retry, and this is the first try
- ALLOW_RETRY and TRIED: this means the page fault allows to
retry, and this is not the first try
- !ALLOW_RETRY and !TRIED: this means the page fault does not allow
to retry at all
- !ALLOW_RETRY and TRIED: this is forbidden and should never be used
In existing code we have multiple places that has taken special care of
the first condition above by checking against (fault_flags &
FAULT_FLAG_ALLOW_RETRY). This patch introduces a simple helper to detect
the first retry of a page fault by checking against both (fault_flags &
FAULT_FLAG_ALLOW_RETRY) and !(fault_flag & FAULT_FLAG_TRIED) because now
even the 2nd try will have the ALLOW_RETRY set, then use that helper in
all existing special paths. One example is in __lock_page_or_retry(), now
we'll drop the mmap_sem only in the first attempt of page fault and we'll
keep it in follow up retries, so old locking behavior will be retained.
This will be a nice enhancement for current code [2] at the same time a
supporting material for the future userfaultfd-writeprotect work, since in
that work there will always be an explicit userfault writeprotect retry
for protected pages, and if that cannot resolve the page fault (e.g., when
userfaultfd-writeprotect is used in conjunction with swapped pages) then
we'll possibly need a 3rd retry of the page fault. It might also benefit
other potential users who will have similar requirement like userfault
write-protection.
GUP code is not touched yet and will be covered in follow up patch.
Please read the thread below for more information.
[1] https://lore.kernel.org/lkml/20171102193644.GB22686@redhat.com/
[2] https://lore.kernel.org/lkml/20181230154648.GB9832@redhat.com/
Suggested-by: Linus Torvalds <torvalds@linux-foundation.org>
Suggested-by: Andrea Arcangeli <aarcange@redhat.com>
Signed-off-by: Peter Xu <peterx@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Tested-by: Brian Geffon <bgeffon@google.com>
Cc: Bobby Powers <bobbypowers@gmail.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Denis Plotnikov <dplotnikov@virtuozzo.com>
Cc: "Dr . David Alan Gilbert" <dgilbert@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Jerome Glisse <jglisse@redhat.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: "Kirill A . Shutemov" <kirill@shutemov.name>
Cc: Martin Cracauer <cracauer@cons.org>
Cc: Marty McFadden <mcfadden8@llnl.gov>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Maya Gokhale <gokhale2@llnl.gov>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Mike Rapoport <rppt@linux.vnet.ibm.com>
Cc: Pavel Emelyanov <xemul@openvz.org>
Link: http://lkml.kernel.org/r/20200220160246.9790-1-peterx@redhat.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
- These were never called PCG flags; they've been called FGP flags since
their introduction in 2014.
- The FGP_FOR_MMAP flag was misleadingly documented as if it was an
alternative to FGP_CREAT instead of an option to it.
- Rename the 'offset' parameter to 'index'.
- Capitalisation, formatting, rewording.
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Cc: Pankaj Gupta <pankaj.gupta.linux@gmail.com>
Link: http://lkml.kernel.org/r/20200318140253.6141-9-willy@infradead.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
No in-tree users (proc, madvise, memcg, mincore) can be built as a module.
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Cc: Pankaj Gupta <pankaj.gupta.linux@gmail.com>
Link: http://lkml.kernel.org/r/20200318140253.6141-8-willy@infradead.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The first argument of shrink_readahead_size_eio() is not used. Hence
remove it from the function definition and from all the callers.
Signed-off-by: Souptick Joarder <jrdr.linux@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Link: http://lkml.kernel.org/r/1583868093-24342-1-git-send-email-jrdr.linux@gmail.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Mount failure issue happens under the scenario: Application forked dozens
of threads to mount the same number of cramfs images separately in docker,
but several mounts failed with high probability. Mount failed due to the
checking result of the page(read from the superblock of loop dev) is not
uptodate after wait_on_page_locked(page) returned in function cramfs_read:
wait_on_page_locked(page);
if (!PageUptodate(page)) {
...
}
The reason of the checking result of the page not uptodate: systemd-udevd
read the loopX dev before mount, because the status of loopX is Lo_unbound
at this time, so loop_make_request directly trigger the calling of io_end
handler end_buffer_async_read, which called SetPageError(page). So It
caused the page can't be set to uptodate in function
end_buffer_async_read:
if(page_uptodate && !PageError(page)) {
SetPageUptodate(page);
}
Then mount operation is performed, it used the same page which is just
accessed by systemd-udevd above, Because this page is not uptodate, it
will launch a actual read via submit_bh, then wait on this page by calling
wait_on_page_locked(page). When the I/O of the page done, io_end handler
end_buffer_async_read is called, because no one cleared the page
error(during the whole read path of mount), which is caused by
systemd-udevd reading, so this page is still in "PageError" status, which
can't be set to uptodate in function end_buffer_async_read, then caused
mount failure.
But sometimes mount succeed even through systemd-udeved read loopX dev
just before, The reason is systemd-udevd launched other loopX read just
between step 3.1 and 3.2, the steps as below:
1, loopX dev default status is Lo_unbound;
2, systemd-udved read loopX dev (page is set to PageError);
3, mount operation
1) set loopX status to Lo_bound;
==>systemd-udevd read loopX dev<==
2) read loopX dev(page has no error)
3) mount succeed
As the loopX dev status is set to Lo_bound after step 3.1, so the other
loopX dev read by systemd-udevd will go through the whole I/O stack, part
of the call trace as below:
SYS_read
vfs_read
do_sync_read
blkdev_aio_read
generic_file_aio_read
do_generic_file_read:
ClearPageError(page);
mapping->a_ops->readpage(filp, page);
here, mapping->a_ops->readpage() is blkdev_readpage. In latest kernel,
some function name changed, the call trace as below:
blkdev_read_iter
generic_file_read_iter
generic_file_buffered_read:
/*
* A previous I/O error may have been due to temporary
* failures, eg. mutipath errors.
* Pg_error will be set again if readpage fails.
*/
ClearPageError(page);
/* Start the actual read. The read will unlock the page*/
error=mapping->a_ops->readpage(flip, page);
We can see ClearPageError(page) is called before the actual read,
then the read in step 3.2 succeed.
This patch is to add the calling of ClearPageError just before the actual
read of read path of cramfs mount. Without the patch, the call trace as
below when performing cramfs mount:
do_mount
cramfs_read
cramfs_blkdev_read
read_cache_page
do_read_cache_page:
filler(data, page);
or
mapping->a_ops->readpage(data, page);
With the patch, the call trace as below when performing mount:
do_mount
cramfs_read
cramfs_blkdev_read
read_cache_page:
do_read_cache_page:
ClearPageError(page); <== new add
filler(data, page);
or
mapping->a_ops->readpage(data, page);
With the patch, mount operation trigger the calling of
ClearPageError(page) before the actual read, the page has no error if no
additional page error happen when I/O done.
Signed-off-by: Xianting Tian <xianting_tian@126.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Jan Kara <jack@suse.cz>
Cc: <yubin@h3c.com>
Link: http://lkml.kernel.org/r/1583318844-22971-1-git-send-email-xianting_tian@126.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
When handling a page fault, we drop mmap_sem to start async readahead so
that we don't block on IO submission with mmap_sem held. However there's
no point to drop mmap_sem in case readahead is disabled. Handle that case
to avoid pointless dropping of mmap_sem and retrying the fault. This was
actually reported to block mlockall(MCL_CURRENT) indefinitely.
Fixes: 6b4c9f4469 ("filemap: drop the mmap_sem for all blocking operations")
Reported-by: Minchan Kim <minchan@kernel.org>
Reported-by: Robert Stupp <snazy@gmx.de>
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: Minchan Kim <minchan@kernel.org>
Link: http://lkml.kernel.org/r/20200212101356.30759-1-jack@suse.cz
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
At some point filemap_write_and_wait() and
filemap_write_and_wait_range() got the exact same implementation with
the exception of the range being specified in *_range()
Similar to other functions in fs.h which call *_range(..., 0,
LLONG_MAX), change filemap_write_and_wait() to be a static inline which
calls filemap_write_and_wait_range()
Link: http://lkml.kernel.org/r/20191129160713.30892-1-ira.weiny@intel.com
Signed-off-by: Ira Weiny <ira.weiny@intel.com>
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
One of our services is observing hanging ps/top/etc under heavy write
IO, and the task states show this is an mmap_sem priority inversion:
A write fault is holding the mmap_sem in read-mode and waiting for
(heavily cgroup-limited) IO in balance_dirty_pages():
balance_dirty_pages+0x724/0x905
balance_dirty_pages_ratelimited+0x254/0x390
fault_dirty_shared_page.isra.96+0x4a/0x90
do_wp_page+0x33e/0x400
__handle_mm_fault+0x6f0/0xfa0
handle_mm_fault+0xe4/0x200
__do_page_fault+0x22b/0x4a0
page_fault+0x45/0x50
Somebody tries to change the address space, contending for the mmap_sem in
write-mode:
call_rwsem_down_write_failed_killable+0x13/0x20
do_mprotect_pkey+0xa8/0x330
SyS_mprotect+0xf/0x20
do_syscall_64+0x5b/0x100
entry_SYSCALL_64_after_hwframe+0x3d/0xa2
The waiting writer locks out all subsequent readers to avoid lock
starvation, and several threads can be seen hanging like this:
call_rwsem_down_read_failed+0x14/0x30
proc_pid_cmdline_read+0xa0/0x480
__vfs_read+0x23/0x140
vfs_read+0x87/0x130
SyS_read+0x42/0x90
do_syscall_64+0x5b/0x100
entry_SYSCALL_64_after_hwframe+0x3d/0xa2
To fix this, do what we do for cache read faults already: drop the
mmap_sem before calling into anything IO bound, in this case the
balance_dirty_pages() function, and return VM_FAULT_RETRY.
Link: http://lkml.kernel.org/r/20190924194238.GA29030@cmpxchg.org
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Reviewed-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Josef Bacik <josef@toxicpanda.com>
Cc: Hillf Danton <hdanton@sina.com>
Cc: Hugh Dickins <hughd@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
generic_file_direct_write() tries to invalidate pagecache after O_DIRECT
write. Unlike to similar code in dio_complete() this silently ignores
error returned from invalidate_inode_pages2_range().
According to comment this code here because not all filesystems call
dio_complete() to do proper invalidation after O_DIRECT write. Noticeable
example is a blkdev_direct_IO().
This patch calls dio_warn_stale_pagecache() if invalidation fails.
Link: http://lkml.kernel.org/r/157270038294.4812.2238891109785106069.stgit@buzz
Signed-off-by: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Jan Kara <jack@suse.cz>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This helper prints warning if direct I/O write failed to invalidate cache,
and set EIO at inode to warn usersapce about possible data corruption.
See also commit 5a9d929d6e ("iomap: report collisions between directio
and buffered writes to userspace").
Direct I/O is supported by non-disk filesystems, for example NFS. Thus
generic code needs this even in kernel without CONFIG_BLOCK.
Link: http://lkml.kernel.org/r/157270038074.4812.7980855544557488880.stgit@buzz
Signed-off-by: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Jan Kara <jack@suse.cz>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
generic_file_direct_write() invalidates cache at entry. Second time this
should be done when request completes. But this function calls second
invalidation at exit unconditionally even for async requests.
This patch skips second invalidation for async requests (-EIOCBQUEUED).
Link: http://lkml.kernel.org/r/157270037850.4812.15036239021726025572.stgit@buzz
Signed-off-by: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Jan Kara <jack@suse.cz>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The generic_file_vm_ops is defined in <linux/ramfs.h> so include it to
fix the following warning:
mm/filemap.c:2717:35: warning: symbol 'generic_file_vm_ops' was not declared. Should it be static?
Link: http://lkml.kernel.org/r/20191008102311.25432-1-ben.dooks@codethink.co.uk
Signed-off-by: Ben Dooks <ben.dooks@codethink.co.uk>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
In previous patch, an application could put part of its text section in
THP via madvise(). These THPs will be protected from writes when the
application is still running (TXTBSY). However, after the application
exits, the file is available for writes.
This patch avoids writes to file THP by dropping page cache for the file
when the file is open for write. A new counter nr_thps is added to struct
address_space. In do_dentry_open(), if the file is open for write and
nr_thps is non-zero, we drop page cache for the whole file.
Link: http://lkml.kernel.org/r/20190801184244.3169074-8-songliubraving@fb.com
Signed-off-by: Song Liu <songliubraving@fb.com>
Reported-by: kbuild test robot <lkp@intel.com>
Acked-by: Rik van Riel <riel@surriel.com>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: Hillf Danton <hdanton@sina.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: William Kucharski <william.kucharski@oracle.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This patch is (hopefully) the first step to enable THP for non-shmem
filesystems.
This patch enables an application to put part of its text sections to THP
via madvise, for example:
madvise((void *)0x600000, 0x200000, MADV_HUGEPAGE);
We tried to reuse the logic for THP on tmpfs.
Currently, write is not supported for non-shmem THP. khugepaged will only
process vma with VM_DENYWRITE. sys_mmap() ignores VM_DENYWRITE requests
(see ksys_mmap_pgoff). The only way to create vma with VM_DENYWRITE is
execve(). This requirement limits non-shmem THP to text sections.
The next patch will handle writes, which would only happen when the all
the vmas with VM_DENYWRITE are unmapped.
An EXPERIMENTAL config, READ_ONLY_THP_FOR_FS, is added to gate this
feature.
[songliubraving@fb.com: fix build without CONFIG_SHMEM]
Link: http://lkml.kernel.org/r/F53407FB-96CC-42E8-9862-105C92CC2B98@fb.com
[songliubraving@fb.com: fix double unlock in collapse_file()]
Link: http://lkml.kernel.org/r/B960CBFA-8EFC-4DA4-ABC5-1977FFF2CA57@fb.com
Link: http://lkml.kernel.org/r/20190801184244.3169074-7-songliubraving@fb.com
Signed-off-by: Song Liu <songliubraving@fb.com>
Acked-by: Rik van Riel <riel@surriel.com>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Cc: Dan Carpenter <dan.carpenter@oracle.com>
Cc: Hillf Danton <hdanton@sina.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: William Kucharski <william.kucharski@oracle.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
With THP, current check of offset:
VM_BUG_ON_PAGE(page->index != offset, page);
is no longer accurate. Update it to:
VM_BUG_ON_PAGE(page_to_pgoff(page) != offset, page);
Link: http://lkml.kernel.org/r/20190801184244.3169074-4-songliubraving@fb.com
Signed-off-by: Song Liu <songliubraving@fb.com>
Acked-by: Rik van Riel <riel@surriel.com>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: Hillf Danton <hdanton@sina.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: William Kucharski <william.kucharski@oracle.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Similar to previous patch, pagecache_get_page() avoids race condition with
truncate by checking page->mapping == mapping. This does not work for
compound pages. This patch let it check compound_head(page)->mapping
instead.
Link: http://lkml.kernel.org/r/20190801184244.3169074-3-songliubraving@fb.com
Signed-off-by: Song Liu <songliubraving@fb.com>
Suggested-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: Hillf Danton <hdanton@sina.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Rik van Riel <riel@surriel.com>
Cc: William Kucharski <william.kucharski@oracle.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Patch series "Enable THP for text section of non-shmem files", v10;
This patchset follows up discussion at LSF/MM 2019. The motivation is to
put text section of an application in THP, and thus reduces iTLB miss rate
and improves performance. Both Facebook and Oracle showed strong
interests to this feature.
To make reviews easier, this set aims a mininal valid product. Current
version of the work does not have any changes to file system specific
code. This comes with some limitations (discussed later).
This set enables an application to "hugify" its text section by simply
running something like:
madvise(0x600000, 0x80000, MADV_HUGEPAGE);
Before this call, the /proc/<pid>/maps looks like:
00400000-074d0000 r-xp 00000000 00:27 2006927 app
After this call, part of the text section is split out and mapped to
THP:
00400000-00425000 r-xp 00000000 00:27 2006927 app
00600000-00e00000 r-xp 00200000 00:27 2006927 app <<< on THP
00e00000-074d0000 r-xp 00a00000 00:27 2006927 app
Limitations:
1. This only works for text section (vma with VM_DENYWRITE).
2. Original limitation #2 is removed in v3.
We gated this feature with an experimental config, READ_ONLY_THP_FOR_FS.
Once we get better support on the write path, we can remove the config and
enable it by default.
Tested cases:
1. Tested with btrfs and ext4.
2. Tested with real work application (memcache like caching service).
3. Tested with "THP aware uprobe":
https://patchwork.kernel.org/project/linux-mm/list/?series=131339
This patch (of 7):
Currently, filemap_fault() avoids race condition with truncate by checking
page->mapping == mapping. This does not work for compound pages. This
patch let it check compound_head(page)->mapping instead.
Link: http://lkml.kernel.org/r/20190801184244.3169074-2-songliubraving@fb.com
Signed-off-by: Song Liu <songliubraving@fb.com>
Acked-by: Rik van Riel <riel@surriel.com>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: William Kucharski <william.kucharski@oracle.com>
Cc: Hillf Danton <hdanton@sina.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Transparent Huge Pages are currently stored in i_pages as pointers to
consecutive subpages. This patch changes that to storing consecutive
pointers to the head page in preparation for storing huge pages more
efficiently in i_pages.
Large parts of this are "inspired" by Kirill's patch
https://lore.kernel.org/lkml/20170126115819.58875-2-kirill.shutemov@linux.intel.com/
Kirill and Huang Ying contributed several fixes.
[willy@infradead.org: use compound_nr, squish uninit-var warning]
Link: http://lkml.kernel.org/r/20190731210400.7419-1-willy@infradead.org
Signed-off-by: Matthew Wilcox <willy@infradead.org>
Acked-by: Jan Kara <jack@suse.cz>
Reviewed-by: Kirill Shutemov <kirill@shutemov.name>
Reviewed-by: Song Liu <songliubraving@fb.com>
Tested-by: Song Liu <songliubraving@fb.com>
Tested-by: William Kucharski <william.kucharski@oracle.com>
Reviewed-by: William Kucharski <william.kucharski@oracle.com>
Tested-by: Qian Cai <cai@lca.pw>
Tested-by: Mikhail Gavrilov <mikhail.v.gavrilov@gmail.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Song Liu <songliubraving@fb.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This actually checks that writeback is needed or in progress.
Link: http://lkml.kernel.org/r/156378817069.1087.1302816672037672488.stgit@buzz
Signed-off-by: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Tejun Heo <tj@kernel.org>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Jan Kara <jack@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Functions like filemap_write_and_wait_range() should do nothing if inode
has no dirty pages or pages currently under writeback. But they anyway
construct struct writeback_control and this does some atomic operations if
CONFIG_CGROUP_WRITEBACK=y - on fast path it locks inode->i_lock and
updates state of writeback ownership, on slow path might be more work.
Current this path is safely avoided only when inode mapping has no pages.
For example generic_file_read_iter() calls filemap_write_and_wait_range()
at each O_DIRECT read - pretty hot path.
This patch skips starting new writeback if mapping has no dirty tags set.
If writeback is already in progress filemap_write_and_wait_range() will
wait for it.
Link: http://lkml.kernel.org/r/156378816804.1087.8607636317907921438.stgit@buzz
Signed-off-by: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
Reviewed-by: Jan Kara <jack@suse.cz>
Cc: Tejun Heo <tj@kernel.org>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Replace 1 << compound_order(page) with compound_nr(page). Minor
improvements in readability.
Link: http://lkml.kernel.org/r/20190721104612.19120-4-willy@infradead.org
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Ira Weiny <ira.weiny@intel.com>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Michal Hocko <mhocko@suse.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Don't let userspace write to an active swap file because the kernel
effectively has a long term lease on the storage and things could get
seriously corrupted if we let this happen.
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Commit 6b4c9f4469 ("filemap: drop the mmap_sem for all blocking
operations") changed when mmap_sem is dropped during filemap page fault
and when returning VM_FAULT_RETRY.
Correct the comment to reflect the change.
Link: http://lkml.kernel.org/r/1556234531-108228-1-git-send-email-yang.shi@linux.alibaba.com
Signed-off-by: Yang Shi <yang.shi@linux.alibaba.com>
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Acked-by: Song Liu <songliubraving@fb.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
We can just pass a NULL filler and do the right thing inside of
do_read_cache_page based on the NULL parameter.
Link: http://lkml.kernel.org/r/20190520055731.24538-3-hch@lst.de
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Kees Cook <keescook@chromium.org>
Cc: Nick Desaulniers <ndesaulniers@google.com>
Cc: Sami Tolvanen <samitolvanen@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Patch series "fix filler_t callback type mismatches", v2.
Casting mapping->a_ops->readpage to filler_t causes an indirect call
type mismatch with Control-Flow Integrity checking. This change fixes
the mismatch in read_cache_page_gfp and read_mapping_page by adding
using a NULL filler argument as an indication to call ->readpage
directly, and by passing the right parameter callbacks in nfs and jffs2.
This patch (of 4):
Code cleanup.
Link: http://lkml.kernel.org/r/20190520055731.24538-2-hch@lst.de
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Kees Cook <keescook@chromium.org>
Cc: Nick Desaulniers <ndesaulniers@google.com>
Cc: Sami Tolvanen <samitolvanen@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
lookups.
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Merge tag 'ext4_for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4
Pull ext4 updates from Ted Ts'o:
"Many bug fixes and cleanups, and an optimization for case-insensitive
lookups"
* tag 'ext4_for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4:
ext4: fix coverity warning on error path of filename setup
ext4: replace ktype default_attrs with default_groups
ext4: rename htree_inline_dir_to_tree() to ext4_inlinedir_to_tree()
ext4: refactor initialize_dirent_tail()
ext4: rename "dirent_csum" functions to use "dirblock"
ext4: allow directory holes
jbd2: drop declaration of journal_sync_buffer()
ext4: use jbd2_inode dirty range scoping
jbd2: introduce jbd2_inode dirty range scoping
mm: add filemap_fdatawait_range_keep_errors()
ext4: remove redundant assignment to node
ext4: optimize case-insensitive lookups
ext4: make __ext4_get_inode_loc plug
ext4: clean up kerneldoc warnigns when building with W=1
ext4: only set project inherit bit for directory
ext4: enforce the immutable flag on open files
ext4: don't allow any modifications to an immutable file
jbd2: fix typo in comment of journal_submit_inode_data_buffers
jbd2: fix some print format mistakes
ext4: gracefully handle ext4_break_layouts() failure during truncate
- Create a generic copy_file_range handler and make individual
filesystems responsible for calling it (i.e. no more assuming that
do_splice_direct will work or is appropriate)
- Refactor copy_file_range and remap_range parameter checking where they
are the same
- Install missing copy_file_range parameter checking(!)
- Remove suid/sgid and update mtime like any other file write
- Change the behavior so that a copy range crossing the source file's
eof will result in a short copy to the source file's eof instead of
EINVAL
- Permit filesystems to decide if they want to handle cross-superblock
copy_file_range in their local handlers.
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Merge tag 'copy-file-range-fixes-1' of git://git.kernel.org/pub/scm/fs/xfs/xfs-linux
Pull copy_file_range updates from Darrick Wong:
"This fixes numerous parameter checking problems and inconsistent
behaviors in the new(ish) copy_file_range system call.
Now the system call will actually check its range parameters
correctly; refuse to copy into files for which the caller does not
have sufficient privileges; update mtime and strip setuid like file
writes are supposed to do; and allows copying up to the EOF of the
source file instead of failing the call like we used to.
Summary:
- Create a generic copy_file_range handler and make individual
filesystems responsible for calling it (i.e. no more assuming that
do_splice_direct will work or is appropriate)
- Refactor copy_file_range and remap_range parameter checking where
they are the same
- Install missing copy_file_range parameter checking(!)
- Remove suid/sgid and update mtime like any other file write
- Change the behavior so that a copy range crossing the source file's
eof will result in a short copy to the source file's eof instead of
EINVAL
- Permit filesystems to decide if they want to handle
cross-superblock copy_file_range in their local handlers"
* tag 'copy-file-range-fixes-1' of git://git.kernel.org/pub/scm/fs/xfs/xfs-linux:
fuse: copy_file_range needs to strip setuid bits and update timestamps
vfs: allow copy_file_range to copy across devices
xfs: use file_modified() helper
vfs: introduce file_modified() helper
vfs: add missing checks to copy_file_range
vfs: remove redundant checks from generic_remap_checks()
vfs: introduce generic_file_rw_checks()
vfs: no fallback for ->copy_file_range
vfs: introduce generic_copy_file_range()
In the spirit of filemap_fdatawait_range() and
filemap_fdatawait_keep_errors(), introduce
filemap_fdatawait_range_keep_errors() which both takes a range upon
which to wait and does not clear errors from the address space.
Signed-off-by: Ross Zwisler <zwisler@google.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Reviewed-by: Jan Kara <jack@suse.cz>
Cc: stable@vger.kernel.org
Like the clone and dedupe interfaces we've recently fixed, the
copy_file_range() implementation is missing basic sanity, limits and
boundary condition tests on the parameters that are passed to it
from userspace. Create a new "generic_copy_file_checks()" function
modelled on the generic_remap_checks() function to provide this
missing functionality.
[Amir] Shorten copy length instead of checking pos_in limits
because input file size already abides by the limits.
Signed-off-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
The access limit checks on input file range in generic_remap_checks()
are redundant because the input file size is guaranteed to be within
limits and pos+len are already checked to be within input file size.
Beyond the fact that the check cannot fail, if it would have failed,
it could return -EFBIG for input file range error. There is no precedent
for that. -EFBIG is returned in syscalls that would change file length.
With that call removed, we can fold generic_access_check_limits() into
generic_write_check_limits().
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Factor out helper with some checks on in/out file that are
common to clone_file_range and copy_file_range.
Suggested-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Add SPDX license identifiers to all files which:
- Have no license information of any form
- Have EXPORT_.*_SYMBOL_GPL inside which was used in the
initial scan/conversion to ignore the file
These files fall under the project license, GPL v2 only. The resulting SPDX
license identifier is:
GPL-2.0-only
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
I removed the only user of this and hadn't noticed it was now unused.
Link: http://lkml.kernel.org/r/20190430152929.21813-1-willy@infradead.org
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Ross Zwisler <zwisler@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Recently I messed up the error handling in filemap_fault() because of an
unexpected ENOMEM (related to cgroup memory limits) in add_to_page_cache.
Enable error injection at this point so I can add a testcase to xfstests
to verify I don't mess this up again.
[akpm@linux-foundation.org: include linux/error-injection.h]
Link: http://lkml.kernel.org/r/20190403152604.14008-1-josef@toxicpanda.com
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: William Kucharski <william.kucharski@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Transparent Huge Pages are currently stored in i_pages as pointers to
consecutive subpages. This patch changes that to storing consecutive
pointers to the head page in preparation for storing huge pages more
efficiently in i_pages.
Large parts of this are "inspired" by Kirill's patch
https://lore.kernel.org/lkml/20170126115819.58875-2-kirill.shutemov@linux.intel.com/
[willy@infradead.org: fix swapcache pages]
Link: http://lkml.kernel.org/r/20190324155441.GF10344@bombadil.infradead.org
[kirill@shutemov.name: hugetlb stores pages in page cache differently]
Link: http://lkml.kernel.org/r/20190404134553.vuvhgmghlkiw2hgl@kshutemo-mobl1
Link: http://lkml.kernel.org/r/20190307153051.18815-1-willy@infradead.org
Signed-off-by: Matthew Wilcox <willy@infradead.org>
Acked-by: Jan Kara <jack@suse.cz>
Reviewed-by: Kirill Shutemov <kirill@shutemov.name>
Reviewed-and-tested-by: Song Liu <songliubraving@fb.com>
Tested-by: William Kucharski <william.kucharski@oracle.com>
Reviewed-by: William Kucharski <william.kucharski@oracle.com>
Tested-by: Qian Cai <cai@lca.pw>
Cc: Hugh Dickins <hughd@google.com>
Cc: Song Liu <liu.song.a23@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
I thought Josef Bacik's patch to drop the mmap_sem was buggy, because
when looking at the error cases, there was one case where we returned
VM_FAULT_RETRY without actually dropping the mmap_sem.
Josef had to explain to me (using small words) that yes, that's actually
what we're supposed to do, and his patch was correct. Which not only
convinced me he knew what he was doing and I should stop arguing with
him, but also that I should add a comment to the case I was confused
about.
Patiently-pointed-out-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Currently we only drop the mmap_sem if there is contention on the page
lock. The idea is that we issue readahead and then go to lock the page
while it is under IO and we want to not hold the mmap_sem during the IO.
The problem with this is the assumption that the readahead does anything.
In the case that the box is under extreme memory or IO pressure we may end
up not reading anything at all for readahead, which means we will end up
reading in the page under the mmap_sem.
Even if the readahead does something, it could get throttled because of io
pressure on the system and the process is in a lower priority cgroup.
Holding the mmap_sem while doing IO is problematic because it can cause
system-wide priority inversions. Consider some large company that does a
lot of web traffic. This large company has load balancing logic in it's
core web server, cause some engineer thought this was a brilliant plan.
This load balancing logic gets statistics from /proc about the system,
which trip over processes mmap_sem for various reasons. Now the web
server application is in a protected cgroup, but these other processes may
not be, and if they are being throttled while their mmap_sem is held we'll
stall, and cause this nice death spiral.
Instead rework filemap fault path to drop the mmap sem at any point that
we may do IO or block for an extended period of time. This includes while
issuing readahead, locking the page, or needing to call ->readpage because
readahead did not occur. Then once we have a fully uptodate page we can
return with VM_FAULT_RETRY and come back again to find our nicely in-cache
page that was gotten outside of the mmap_sem.
This patch also adds a new helper for locking the page with the mmap_sem
dropped. This doesn't make sense currently as generally speaking if the
page is already locked it'll have been read in (unless there was an error)
before it was unlocked. However a forthcoming patchset will change this
with the ability to abort read-ahead bio's if necessary, making it more
likely that we could contend for a page lock and still have a not uptodate
page. This allows us to deal with this case by grabbing the lock and
issuing the IO without the mmap_sem held, and then returning
VM_FAULT_RETRY to come back around.
[josef@toxicpanda.com: v6]
Link: http://lkml.kernel.org/r/20181212152757.10017-1-josef@toxicpanda.com
[kirill@shutemov.name: fix race in filemap_fault()]
Link: http://lkml.kernel.org/r/20181228235106.okk3oastsnpxusxs@kshutemo-mobl1
[akpm@linux-foundation.org: coding style fixes]
Link: http://lkml.kernel.org/r/20181211173801.29535-4-josef@toxicpanda.com
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Jan Kara <jack@suse.cz>
Tested-by: syzbot+b437b5a429d680cf2217@syzkaller.appspotmail.com
Cc: Dave Chinner <david@fromorbit.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: "Kirill A. Shutemov" <kirill@shutemov.name>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Patch series "drop the mmap_sem when doing IO in the fault path", v6.
Now that we have proper isolation in place with cgroups2 we have started
going through and fixing the various priority inversions. Most are all
gone now, but this one is sort of weird since it's not necessarily a
priority inversion that happens within the kernel, but rather because of
something userspace does.
We have giant applications that we want to protect, and parts of these
giant applications do things like watch the system state to determine how
healthy the box is for load balancing and such. This involves running
'ps' or other such utilities. These utilities will often walk
/proc/<pid>/whatever, and these files can sometimes need to
down_read(&task->mmap_sem). Not usually a big deal, but we noticed when
we are stress testing that sometimes our protected application has latency
spikes trying to get the mmap_sem for tasks that are in lower priority
cgroups.
This is because any down_write() on a semaphore essentially turns it into
a mutex, so even if we currently have it held for reading, any new readers
will not be allowed on to keep from starving the writer. This is fine,
except a lower priority task could be stuck doing IO because it has been
throttled to the point that its IO is taking much longer than normal. But
because a higher priority group depends on this completing it is now stuck
behind lower priority work.
In order to avoid this particular priority inversion we want to use the
existing retry mechanism to stop from holding the mmap_sem at all if we
are going to do IO. This already exists in the read case sort of, but
needed to be extended for more than just grabbing the page lock. With
io.latency we throttle at submit_bio() time, so the readahead stuff can
block and even page_cache_read can block, so all these paths need to have
the mmap_sem dropped.
The other big thing is ->page_mkwrite. btrfs is particularly shitty here
because we have to reserve space for the dirty page, which can be a very
expensive operation. We use the same retry method as the read path, and
simply cache the page and verify the page is still setup properly the next
pass through ->page_mkwrite().
I've tested these patches with xfstests and there are no regressions.
This patch (of 3):
If we do not have a page at filemap_fault time we'll do this weird forced
page_cache_read thing to populate the page, and then drop it again and
loop around and find it. This makes for 2 ways we can read a page in
filemap_fault, and it's not really needed. Instead add a FGP_FOR_MMAP
flag so that pagecache_get_page() will return a unlocked page that's in
pagecache. Then use the normal page locking and readpage logic already in
filemap_fault. This simplifies the no page in page cache case
significantly.
[akpm@linux-foundation.org: fix comment text]
[josef@toxicpanda.com: don't unlock null page in FGP_FOR_MMAP case]
Link: http://lkml.kernel.org/r/20190312201742.22935-1-josef@toxicpanda.com
Link: http://lkml.kernel.org/r/20181211173801.29535-2-josef@toxicpanda.com
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Reviewed-by: Jan Kara <jack@suse.cz>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Tejun Heo <tj@kernel.org>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: "Kirill A. Shutemov" <kirill@shutemov.name>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
All of the arguments to these functions come from the vmf.
Cut down on the amount of arguments passed by simply passing in the vmf
to these two helpers.
Link: http://lkml.kernel.org/r/20181211173801.29535-3-josef@toxicpanda.com
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Jan Kara <jack@suse.cz>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: "Kirill A. Shutemov" <kirill@shutemov.name>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
We have common pattern to access lru_lock from a page pointer:
zone_lru_lock(page_zone(page))
Which is silly, because it unfolds to this:
&NODE_DATA(page_to_nid(page))->node_zones[page_zonenum(page)]->zone_pgdat->lru_lock
while we can simply do
&NODE_DATA(page_to_nid(page))->lru_lock
Remove zone_lru_lock() function, since it's only complicate things. Use
'page_pgdat(page)->lru_lock' pattern instead.
[aryabinin@virtuozzo.com: a slightly better version of __split_huge_page()]
Link: http://lkml.kernel.org/r/20190301121651.7741-1-aryabinin@virtuozzo.com
Link: http://lkml.kernel.org/r/20190228083329.31892-2-aryabinin@virtuozzo.com
Signed-off-by: Andrey Ryabinin <aryabinin@virtuozzo.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Mel Gorman <mgorman@techsingularity.net>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Rik van Riel <riel@surriel.com>
Cc: William Kucharski <william.kucharski@oracle.com>
Cc: John Hubbard <jhubbard@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
find_get_pages_range() and find_get_pages_range_tag() already correctly
increment reference count on head when seeing compound page, but they
may still use page index from tail. Page index from tail is always
zero, so these functions don't work on huge shmem. This hasn't been a
problem because, AFAIK, nobody calls these functions on (huge) shmem.
Fix them anyway just in case.
Link: http://lkml.kernel.org/r/20190110030838.84446-1-yuzhao@google.com
Signed-off-by: Yu Zhao <yuzhao@google.com>
Reviewed-by: William Kucharski <william.kucharski@oracle.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Amir Goldstein <amir73il@gmail.com>
Cc: Dave Chinner <david@fromorbit.com>
Cc: "Darrick J . Wong" <darrick.wong@oracle.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Souptick Joarder <jrdr.linux@gmail.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: "Kirill A . Shutemov" <kirill.shutemov@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Many kernel-doc comments in mm/ have the return value descriptions
either misformatted or omitted at all which makes kernel-doc script
unhappy:
$ make V=1 htmldocs
...
./mm/util.c:36: info: Scanning doc for kstrdup
./mm/util.c:41: warning: No description found for return value of 'kstrdup'
./mm/util.c:57: info: Scanning doc for kstrdup_const
./mm/util.c:66: warning: No description found for return value of 'kstrdup_const'
./mm/util.c:75: info: Scanning doc for kstrndup
./mm/util.c:83: warning: No description found for return value of 'kstrndup'
...
Fixing the formatting and adding the missing return value descriptions
eliminates ~100 such warnings.
Link: http://lkml.kernel.org/r/1549549644-4903-4-git-send-email-rppt@linux.ibm.com
Signed-off-by: Mike Rapoport <rppt@linux.ibm.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The 'end_byte' parameter of filemap_range_has_page is required to be
inclusive, so follow the rule.
Link: http://lkml.kernel.org/r/1548678679-18122-1-git-send-email-zhengbin13@huawei.com
Fixes: 6be96d3ad3 ("fs: return if direct I/O will trigger writeback")
Signed-off-by: zhengbin <zhengbin13@huawei.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Matthew Wilcox <willy@infradead.org>
Acked-by: Christoph Hellwig <hch@lst.de>
Cc: "Darrick J. Wong" <darrick.wong@oracle.com>
Cc: Amir Goldstein <amir73il@gmail.com>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Hugh Dickins <hughd@google.com>
Cc: Hou Tao <houtao1@huawei.com>
Cc: zhangyi (F) <yi.zhang@huawei.com>
Cc: Jan Kara <jack@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
After we establish a reference on the page, we check the pointer
continues to be in the correct position in i_pages. Checking
page->index afterwards is unnecessary; if it were to change, then the
pointer to it from the page cache would also move. The check used to be
done before grabbing a reference on the page which was racy (see commit
9cbb4cb21b ("mm: find_get_pages_contig fixlet")), but nobody noticed
that moving the check after grabbing the reference was redundant.
Link: http://lkml.kernel.org/r/20190107200224.13260-1-willy@infradead.org
Signed-off-by: Matthew Wilcox <willy@infradead.org>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Hugh Dickins <hughd@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This is already done for us internally by the signal machinery.
Link: http://lkml.kernel.org/r/20181116002713.8474-5-dave@stgolabs.net
Signed-off-by: Davidlohr Bueso <dave@stgolabs.net>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
filemap_map_pages takes a speculative reference to each page in the range
before it tries to lock that page. While this is correct it also can
influence page migration which will bail out when seeing an elevated
reference count. The faultaround code would bail on seeing a locked page
so we can pro-actively check the PageLocked bit before
page_cache_get_speculative and prevent from pointless reference count
churn.
Link: http://lkml.kernel.org/r/20181211142741.2607-4-mhocko@kernel.org
Signed-off-by: Michal Hocko <mhocko@suse.com>
Suggested-by: Jan Kara <jack@suse.cz>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Acked-by: Hugh Dickins <hughd@google.com>
Reviewed-by: William Kucharski <william.kucharski@oracle.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Pavel Tatashin <pasha.tatashin@soleen.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
page always is not NULL, so we may remove this useless check.
Link: http://lkml.kernel.org/r/154419752044.18559.2452963074922917720.stgit@localhost.localdomain
Signed-off-by: Kirill Tkhai <ktkhai@virtuozzo.com>
Acked-by: Cyrill Gorcunov <gorcunov@gmail.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Waiting on a page migration entry has used wait_on_page_locked() all along
since 2006: but you cannot safely wait_on_page_locked() without holding a
reference to the page, and that extra reference is enough to make
migrate_page_move_mapping() fail with -EAGAIN, when a racing task faults
on the entry before migrate_page_move_mapping() gets there.
And that failure is retried nine times, amplifying the pain when trying to
migrate a popular page. With a single persistent faulter, migration
sometimes succeeds; with two or three concurrent faulters, success becomes
much less likely (and the more the page was mapped, the worse the overhead
of unmapping and remapping it on each try).
This is especially a problem for memory offlining, where the outer level
retries forever (or until terminated from userspace), because a heavy
refault workload can trigger an endless loop of migration failures.
wait_on_page_locked() is the wrong tool for the job.
David Herrmann (but was he the first?) noticed this issue in 2014:
https://marc.info/?l=linux-mm&m=140110465608116&w=2
Tim Chen started a thread in August 2017 which appears relevant:
https://marc.info/?l=linux-mm&m=150275941014915&w=2 where Kan Liang went
on to implicate __migration_entry_wait():
https://marc.info/?l=linux-mm&m=150300268411980&w=2 and the thread ended
up with the v4.14 commits: 2554db9165 ("sched/wait: Break up long wake
list walk") 11a19c7b09 ("sched/wait: Introduce wakeup boomark in
wake_up_page_bit")
Baoquan He reported "Memory hotplug softlock issue" 14 November 2018:
https://marc.info/?l=linux-mm&m=154217936431300&w=2
We have all assumed that it is essential to hold a page reference while
waiting on a page lock: partly to guarantee that there is still a struct
page when MEMORY_HOTREMOVE is configured, but also to protect against
reuse of the struct page going to someone who then holds the page locked
indefinitely, when the waiter can reasonably expect timely unlocking.
But in fact, so long as wait_on_page_bit_common() does the put_page(), and
is careful not to rely on struct page contents thereafter, there is no
need to hold a reference to the page while waiting on it. That does mean
that this case cannot go back through the loop: but that's fine for the
page migration case, and even if used more widely, is limited by the "Stop
walking if it's locked" optimization in wake_page_function().
Add interface put_and_wait_on_page_locked() to do this, using "behavior"
enum in place of "lock" arg to wait_on_page_bit_common() to implement it.
No interruptible or killable variant needed yet, but they might follow: I
have a vague notion that reporting -EINTR should take precedence over
return from wait_on_page_bit_common() without knowing the page state, so
arrange it accordingly - but that may be nothing but pedantic.
__migration_entry_wait() still has to take a brief reference to the page,
prior to calling put_and_wait_on_page_locked(): but now that it is dropped
before waiting, the chance of impeding page migration is very much
reduced. Should we perhaps disable preemption across this?
shrink_page_list()'s __ClearPageLocked(): that was a surprise! This
survived a lot of testing before that showed up. PageWaiters may have
been set by wait_on_page_bit_common(), and the reference dropped, just
before shrink_page_list() succeeds in freezing its last page reference: in
such a case, unlock_page() must be used. Follow the suggestion from
Michal Hocko, just revert a978d6f521 ("mm: unlockless reclaim") now:
that optimization predates PageWaiters, and won't buy much these days; but
we can reinstate it for the !PageWaiters case if anyone notices.
It does raise the question: should vmscan.c's is_page_cache_freeable() and
__remove_mapping() now treat a PageWaiters page as if an extra reference
were held? Perhaps, but I don't think it matters much, since
shrink_page_list() already had to win its trylock_page(), so waiters are
not very common there: I noticed no difference when trying the bigger
change, and it's surely not needed while put_and_wait_on_page_locked() is
only used for page migration.
[willy@infradead.org: add put_and_wait_on_page_locked() kerneldoc]
Link: http://lkml.kernel.org/r/alpine.LSU.2.11.1811261121330.1116@eggly.anvils
Signed-off-by: Hugh Dickins <hughd@google.com>
Reported-by: Baoquan He <bhe@redhat.com>
Tested-by: Baoquan He <bhe@redhat.com>
Reviewed-by: Andrea Arcangeli <aarcange@redhat.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Baoquan He <bhe@redhat.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: David Herrmann <dh.herrmann@gmail.com>
Cc: Tim Chen <tim.c.chen@linux.intel.com>
Cc: Kan Liang <kan.liang@intel.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Christoph Lameter <cl@linux.com>
Cc: Nick Piggin <npiggin@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Rework the vfs_clone_file_range and vfs_dedupe_file_range infrastructure to use
a common .remap_file_range method and supply generic bounds and sanity checking
functions that are shared with the data write path. The current VFS
infrastructure has problems with rlimit, LFS file sizes, file time stamps,
maximum filesystem file sizes, stripping setuid bits, etc and so they are
addressed in these commits.
We also introduce the ability for the ->remap_file_range methods to return short
clones so that clones for vfs_copy_file_range() don't get rejected if the entire
range can't be cloned. It also allows filesystems to sliently skip deduplication
of partial EOF blocks if they are not capable of doing so without requiring
errors to be thrown to userspace.
All existing filesystems are converted to user the new .remap_file_range method,
and both XFS and ocfs2 are modified to make use of the new generic checking
infrastructure.
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Merge tag 'xfs-4.20-merge-2' of git://git.kernel.org/pub/scm/fs/xfs/xfs-linux
Pull vfs dedup fixes from Dave Chinner:
"This reworks the vfs data cloning infrastructure.
We discovered many issues with these interfaces late in the 4.19 cycle
- the worst of them (data corruption, setuid stripping) were fixed for
XFS in 4.19-rc8, but a larger rework of the infrastructure fixing all
the problems was needed. That rework is the contents of this pull
request.
Rework the vfs_clone_file_range and vfs_dedupe_file_range
infrastructure to use a common .remap_file_range method and supply
generic bounds and sanity checking functions that are shared with the
data write path. The current VFS infrastructure has problems with
rlimit, LFS file sizes, file time stamps, maximum filesystem file
sizes, stripping setuid bits, etc and so they are addressed in these
commits.
We also introduce the ability for the ->remap_file_range methods to
return short clones so that clones for vfs_copy_file_range() don't get
rejected if the entire range can't be cloned. It also allows
filesystems to sliently skip deduplication of partial EOF blocks if
they are not capable of doing so without requiring errors to be thrown
to userspace.
Existing filesystems are converted to user the new remap_file_range
method, and both XFS and ocfs2 are modified to make use of the new
generic checking infrastructure"
* tag 'xfs-4.20-merge-2' of git://git.kernel.org/pub/scm/fs/xfs/xfs-linux: (28 commits)
xfs: remove [cm]time update from reflink calls
xfs: remove xfs_reflink_remap_range
xfs: remove redundant remap partial EOF block checks
xfs: support returning partial reflink results
xfs: clean up xfs_reflink_remap_blocks call site
xfs: fix pagecache truncation prior to reflink
ocfs2: remove ocfs2_reflink_remap_range
ocfs2: support partial clone range and dedupe range
ocfs2: fix pagecache truncation prior to reflink
ocfs2: truncate page cache for clone destination file before remapping
vfs: clean up generic_remap_file_range_prep return value
vfs: hide file range comparison function
vfs: enable remap callers that can handle short operations
vfs: plumb remap flags through the vfs dedupe functions
vfs: plumb remap flags through the vfs clone functions
vfs: make remap_file_range functions take and return bytes completed
vfs: remap helper should update destination inode metadata
vfs: pass remap flags to generic_remap_checks
vfs: pass remap flags to generic_remap_file_range_prep
vfs: combine the clone and dedupe into a single remap_file_range
...
Pull AFS updates from Al Viro:
"AFS series, with some iov_iter bits included"
* 'work.afs' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: (26 commits)
missing bits of "iov_iter: Separate type from direction and use accessor functions"
afs: Probe multiple fileservers simultaneously
afs: Fix callback handling
afs: Eliminate the address pointer from the address list cursor
afs: Allow dumping of server cursor on operation failure
afs: Implement YFS support in the fs client
afs: Expand data structure fields to support YFS
afs: Get the target vnode in afs_rmdir() and get a callback on it
afs: Calc callback expiry in op reply delivery
afs: Fix FS.FetchStatus delivery from updating wrong vnode
afs: Implement the YFS cache manager service
afs: Remove callback details from afs_callback_break struct
afs: Commit the status on a new file/dir/symlink
afs: Increase to 64-bit volume ID and 96-bit vnode ID for YFS
afs: Don't invoke the server to read data beyond EOF
afs: Add a couple of tracepoints to log I/O errors
afs: Handle EIO from delivery function
afs: Fix TTL on VL server and address lists
afs: Implement VL server rotation
afs: Improve FS server rotation error handling
...
Plumb in a remap flag that enables the filesystem remap handler to
shorten remapping requests for callers that can handle it. Now
copy_file_range can report partial success (in case we run up against
alignment problems, resource limits, etc.).
We also enable CAN_SHORTEN for fideduperange to maintain existing
userspace-visible behavior where xfs/btrfs shorten the dedupe range to
avoid stale post-eof data exposure.
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>
Change the remap_file_range functions to take a number of bytes to
operate upon and return the number of bytes they operated on. This is a
requirement for allowing fs implementations to return short clone/dedupe
results to the user, which will enable us to obey resource limits in a
graceful manner.
A subsequent patch will enable copy_file_range to signal to the
->clone_file_range implementation that it can handle a short length,
which will be returned in the function's return value. For now the
short return is not implemented anywhere so the behavior won't change --
either copy_file_range manages to clone the entire range or it tries an
alternative.
Neither clone ioctl can take advantage of this, alas.
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>
Pass the same remap flags to generic_remap_checks for consistency.
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Dave Chinner <david@fromorbit.com>
File range remapping, if allowed to run past the destination file's EOF,
is an optimization on a regular file write. Regular file writes that
extend the file length are subject to various constraints which are not
checked by range cloning.
This is a correctness problem because we're never allowed to touch
ranges that the page cache can't support (s_maxbytes); we're not
supposed to deal with large offsets (MAX_NON_LFS) if O_LARGEFILE isn't
set; and we must obey resource limits (RLIMIT_FSIZE).
Therefore, add these checks to the new generic_remap_checks function so
that we curtail unexpected behavior.
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Dave Chinner <david@fromorbit.com>
Move the file range checks from vfs_clone_file_prep into a separate
generic_remap_checks function so that all the checks are collected in a
central location. This forms the basis for adding more checks from
generic_write_checks that will make cloning's input checking more
consistent with write input checking.
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>
Pull XArray conversion from Matthew Wilcox:
"The XArray provides an improved interface to the radix tree data
structure, providing locking as part of the API, specifying GFP flags
at allocation time, eliminating preloading, less re-walking the tree,
more efficient iterations and not exposing RCU-protected pointers to
its users.
This patch set
1. Introduces the XArray implementation
2. Converts the pagecache to use it
3. Converts memremap to use it
The page cache is the most complex and important user of the radix
tree, so converting it was most important. Converting the memremap
code removes the only other user of the multiorder code, which allows
us to remove the radix tree code that supported it.
I have 40+ followup patches to convert many other users of the radix
tree over to the XArray, but I'd like to get this part in first. The
other conversions haven't been in linux-next and aren't suitable for
applying yet, but you can see them in the xarray-conv branch if you're
interested"
* 'xarray' of git://git.infradead.org/users/willy/linux-dax: (90 commits)
radix tree: Remove multiorder support
radix tree test: Convert multiorder tests to XArray
radix tree tests: Convert item_delete_rcu to XArray
radix tree tests: Convert item_kill_tree to XArray
radix tree tests: Move item_insert_order
radix tree test suite: Remove multiorder benchmarking
radix tree test suite: Remove __item_insert
memremap: Convert to XArray
xarray: Add range store functionality
xarray: Move multiorder_check to in-kernel tests
xarray: Move multiorder_shrink to kernel tests
xarray: Move multiorder account test in-kernel
radix tree test suite: Convert iteration test to XArray
radix tree test suite: Convert tag_tagged_items to XArray
radix tree: Remove radix_tree_clear_tags
radix tree: Remove radix_tree_maybe_preload_order
radix tree: Remove split/join code
radix tree: Remove radix_tree_update_node_t
page cache: Finish XArray conversion
dax: Convert page fault handlers to XArray
...
These codes can be replaced with new inline vmf_error().
Link: http://lkml.kernel.org/r/20180927171411.GA23331@jordon-HP-15-Notebook-PC
Signed-off-by: Souptick Joarder <jrdr.linux@gmail.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Use the variable write_len instead of ov_iter_count(from).
Link: http://lkml.kernel.org/r/1537375855-2088-1-git-send-email-leviathan0992@gmail.com
Signed-off-by: haiqing.shq <leviathan0992@gmail.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Jan Kara <jack@suse.cz>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
When systems are overcommitted and resources become contended, it's hard
to tell exactly the impact this has on workload productivity, or how close
the system is to lockups and OOM kills. In particular, when machines work
multiple jobs concurrently, the impact of overcommit in terms of latency
and throughput on the individual job can be enormous.
In order to maximize hardware utilization without sacrificing individual
job health or risk complete machine lockups, this patch implements a way
to quantify resource pressure in the system.
A kernel built with CONFIG_PSI=y creates files in /proc/pressure/ that
expose the percentage of time the system is stalled on CPU, memory, or IO,
respectively. Stall states are aggregate versions of the per-task delay
accounting delays:
cpu: some tasks are runnable but not executing on a CPU
memory: tasks are reclaiming, or waiting for swapin or thrashing cache
io: tasks are waiting for io completions
These percentages of walltime can be thought of as pressure percentages,
and they give a general sense of system health and productivity loss
incurred by resource overcommit. They can also indicate when the system
is approaching lockup scenarios and OOMs.
To do this, psi keeps track of the task states associated with each CPU
and samples the time they spend in stall states. Every 2 seconds, the
samples are averaged across CPUs - weighted by the CPUs' non-idle time to
eliminate artifacts from unused CPUs - and translated into percentages of
walltime. A running average of those percentages is maintained over 10s,
1m, and 5m periods (similar to the loadaverage).
[hannes@cmpxchg.org: doc fixlet, per Randy]
Link: http://lkml.kernel.org/r/20180828205625.GA14030@cmpxchg.org
[hannes@cmpxchg.org: code optimization]
Link: http://lkml.kernel.org/r/20180907175015.GA8479@cmpxchg.org
[hannes@cmpxchg.org: rename psi_clock() to psi_update_work(), per Peter]
Link: http://lkml.kernel.org/r/20180907145404.GB11088@cmpxchg.org
[hannes@cmpxchg.org: fix build]
Link: http://lkml.kernel.org/r/20180913014222.GA2370@cmpxchg.org
Link: http://lkml.kernel.org/r/20180828172258.3185-9-hannes@cmpxchg.org
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Tested-by: Daniel Drake <drake@endlessm.com>
Tested-by: Suren Baghdasaryan <surenb@google.com>
Cc: Christopher Lameter <cl@linux.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Johannes Weiner <jweiner@fb.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Enderborg <peter.enderborg@sony.com>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: Shakeel Butt <shakeelb@google.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Vinayak Menon <vinmenon@codeaurora.org>
Cc: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Delay accounting already measures the time a task spends in direct reclaim
and waiting for swapin, but in low memory situations tasks spend can spend
a significant amount of their time waiting on thrashing page cache. This
isn't tracked right now.
To know the full impact of memory contention on an individual task,
measure the delay when waiting for a recently evicted active cache page to
read back into memory.
Also update tools/accounting/getdelays.c:
[hannes@computer accounting]$ sudo ./getdelays -d -p 1
print delayacct stats ON
PID 1
CPU count real total virtual total delay total delay average
50318 745000000 847346785 400533713 0.008ms
IO count delay total delay average
435 122601218 0ms
SWAP count delay total delay average
0 0 0ms
RECLAIM count delay total delay average
0 0 0ms
THRASHING count delay total delay average
19 12621439 0ms
Link: http://lkml.kernel.org/r/20180828172258.3185-4-hannes@cmpxchg.org
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Tested-by: Daniel Drake <drake@endlessm.com>
Tested-by: Suren Baghdasaryan <surenb@google.com>
Cc: Christopher Lameter <cl@linux.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Johannes Weiner <jweiner@fb.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Enderborg <peter.enderborg@sony.com>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: Shakeel Butt <shakeelb@google.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Vinayak Menon <vinmenon@codeaurora.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Refaults happen during transitions between workingsets as well as in-place
thrashing. Knowing the difference between the two has a range of
applications, including measuring the impact of memory shortage on the
system performance, as well as the ability to smarter balance pressure
between the filesystem cache and the swap-backed workingset.
During workingset transitions, inactive cache refaults and pushes out
established active cache. When that active cache isn't stale, however,
and also ends up refaulting, that's bonafide thrashing.
Introduce a new page flag that tells on eviction whether the page has been
active or not in its lifetime. This bit is then stored in the shadow
entry, to classify refaults as transitioning or thrashing.
How many page->flags does this leave us with on 32-bit?
20 bits are always page flags
21 if you have an MMU
23 with the zone bits for DMA, Normal, HighMem, Movable
29 with the sparsemem section bits
30 if PAE is enabled
31 with this patch.
So on 32-bit PAE, that leaves 1 bit for distinguishing two NUMA nodes. If
that's not enough, the system can switch to discontigmem and re-gain the 6
or 7 sparsemem section bits.
Link: http://lkml.kernel.org/r/20180828172258.3185-3-hannes@cmpxchg.org
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Tested-by: Daniel Drake <drake@endlessm.com>
Tested-by: Suren Baghdasaryan <surenb@google.com>
Cc: Christopher Lameter <cl@linux.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Johannes Weiner <jweiner@fb.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Enderborg <peter.enderborg@sony.com>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: Shakeel Butt <shakeelb@google.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Vinayak Menon <vinmenon@codeaurora.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
As part of vm_fault_t conversion filemap_page_mkwrite() for the NOMMU case
was missed. Now converted.
Link: http://lkml.kernel.org/r/20180828174952.GA29229@jordon-HP-15-Notebook-PC
Signed-off-by: Souptick Joarder <jrdr.linux@gmail.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Matthew Wilcox <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Use accessor functions to access an iterator's type and direction. This
allows for the possibility of using some other method of determining the
type of iterator than if-chains with bitwise-AND conditions.
Signed-off-by: David Howells <dhowells@redhat.com>
Instead of calling find_get_pages_range() and putting any reference,
use xas_find() to iterate over any entries in the range, skipping the
shadow/swap entries.
Signed-off-by: Matthew Wilcox <willy@infradead.org>
Slight change of strategy here; if we have trouble getting hold of a
page for whatever reason (eg a compound page is split underneath us),
don't spin to stabilise the page, just continue the iteration, like we
would if we failed to trylock the page. Since this is a speculative
optimisation, it feels like we should allow the process to take an extra
fault if it turns out to need this page instead of spending time to pin
down a page it may not need.
Signed-off-by: Matthew Wilcox <willy@infradead.org>
The 'end' parameter of the xas_for_each iterator avoids a useless
iteration at the end of the range.
Signed-off-by: Matthew Wilcox <willy@infradead.org>
There's no direct replacement for radix_tree_for_each_contig()
in the XArray API as it's an unusual thing to do. Instead,
open-code a loop using xas_next(). This removes the only user of
radix_tree_for_each_contig() so delete the iterator from the API and
the test suite code for it.
Signed-off-by: Matthew Wilcox <willy@infradead.org>
The 'end' parameter of the xas_for_each iterator avoids a useless
iteration at the end of the range.
Signed-off-by: Matthew Wilcox <willy@infradead.org>
Use the XArray APIs to add and replace pages in the page cache. This
removes two uses of the radix tree preload API and is significantly
shorter code. It also removes the last user of __radix_tree_create()
outside radix-tree.c itself, so make it static.
Signed-off-by: Matthew Wilcox <willy@infradead.org>
The page cache offers the ability to search for a miss in the previous or
next N locations. Rather than teach the XArray about the page cache's
definition of a miss, use xas_prev() and xas_next() to search the page
array. This should be more efficient as it does not have to start the
lookup from the top for each index.
Signed-off-by: Matthew Wilcox <willy@infradead.org>
Introduce xarray value entries and tagged pointers to replace radix
tree exceptional entries. This is a slight change in encoding to allow
the use of an extra bit (we can now store BITS_PER_LONG - 1 bits in a
value entry). It is also a change in emphasis; exceptional entries are
intimidating and different. As the comment explains, you can choose
to store values or pointers in the xarray and they are both first-class
citizens.
Signed-off-by: Matthew Wilcox <willy@infradead.org>
Reviewed-by: Josef Bacik <jbacik@fb.com>
Use new return type vm_fault_t for fault handler in struct
vm_operations_struct. For now, this is just documenting that the
function returns a VM_FAULT value rather than an errno. Once all
instances are converted, vm_fault_t will become a distinct type.
Link: http://lkml.kernel.org/r/20180511190542.GA2412@jordon-HP-15-Notebook-PC
Signed-off-by: Souptick Joarder <jrdr.linux@gmail.com>
Reviewed-by: Matthew Wilcox <mawilcox@microsoft.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Ross Zwisler <ross.zwisler@linux.intel.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Hugh Dickins <hughd@google.com>
Cc: Pavel Tatashin <pasha.tatashin@oracle.com>
Cc: Michal Hocko <mhocko@suse.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
f2fs specifies the __GFP_ZERO flag for allocating some of its pages.
Unfortunately, the page cache also uses the mapping's GFP flags for
allocating radix tree nodes. It always masked off the __GFP_HIGHMEM
flag, and masks off __GFP_ZERO in some paths, but not all. That causes
radix tree nodes to be allocated with a NULL list_head, which causes
backtraces like:
__list_del_entry+0x30/0xd0
list_lru_del+0xac/0x1ac
page_cache_tree_insert+0xd8/0x110
The __GFP_DMA and __GFP_DMA32 flags would also be able to sneak through
if they are ever used. Fix them all by using GFP_RECLAIM_MASK at the
innermost location, and remove it from earlier in the callchain.
Link: http://lkml.kernel.org/r/20180411060320.14458-2-willy@infradead.org
Fixes: 449dd6984d ("mm: keep page cache radix tree nodes in check")
Signed-off-by: Matthew Wilcox <mawilcox@microsoft.com>
Reported-by: Chris Fries <cfries@google.com>
Debugged-by: Minchan Kim <minchan@kernel.org>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Michal Hocko <mhocko@suse.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Building orangefs on MMU-less machines now results in a link error
because of the newly introduced use of the filemap_page_mkwrite()
function:
ERROR: "filemap_page_mkwrite" [fs/orangefs/orangefs.ko] undefined!
This adds a dummy version for it, similar to the existing
generic_file_mmap and generic_file_readonly_mmap stubs in the same file,
to avoid the link error without adding #ifdefs in each file system that
uses these.
Link: http://lkml.kernel.org/r/20180409105555.2439976-1-arnd@arndb.de
Fixes: a5135eeab2 ("orangefs: implement vm_ops->fault")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Reviewed-by: Jan Kara <jack@suse.cz>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Martin Brandenburg <martin@omnibond.com>
Cc: Mike Marshall <hubcap@omnibond.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Remove the address_space ->tree_lock and use the xa_lock newly added to
the radix_tree_root. Rename the address_space ->page_tree to ->i_pages,
since we don't really care that it's a tree.
[willy@infradead.org: fix nds32, fs/dax.c]
Link: http://lkml.kernel.org/r/20180406145415.GB20605@bombadil.infradead.orgLink: http://lkml.kernel.org/r/20180313132639.17387-9-willy@infradead.org
Signed-off-by: Matthew Wilcox <mawilcox@microsoft.com>
Acked-by: Jeff Layton <jlayton@redhat.com>
Cc: Darrick J. Wong <darrick.wong@oracle.com>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
Cc: Will Deacon <will.deacon@arm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
in_atomic() has been moved to include/linux/preempt.h, and the filemap.c
doesn't use in_atomic() directly at all, so it sounds unnecessary to
include hardirq.h.
Link: http://lkml.kernel.org/r/1509985319-38633-1-git-send-email-yang.s@alibaba-inc.com
Signed-off-by: Yang Shi <yang.s@alibaba-inc.com>
Reviewed-by: Matthew Wilcox <mawilcox@microsoft.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Merge tag 'afs-next-20171113' of git://git.kernel.org/pub/scm/linux/kernel/git/dhowells/linux-fs
Pull AFS updates from David Howells:
"kAFS filesystem driver overhaul.
The major points of the overhaul are:
(1) Preliminary groundwork is laid for supporting network-namespacing
of kAFS. The remainder of the namespacing work requires some way
to pass namespace information to submounts triggered by an
automount. This requires something like the mount overhaul that's
in progress.
(2) sockaddr_rxrpc is used in preference to in_addr for holding
addresses internally and add support for talking to the YFS VL
server. With this, kAFS can do everything over IPv6 as well as
IPv4 if it's talking to servers that support it.
(3) Callback handling is overhauled to be generally passive rather
than active. 'Callbacks' are promises by the server to tell us
about data and metadata changes. Callbacks are now checked when
we next touch an inode rather than actively going and looking for
it where possible.
(4) File access permit caching is overhauled to store the caching
information per-inode rather than per-directory, shared over
subordinate files. Whilst older AFS servers only allow ACLs on
directories (shared to the files in that directory), newer AFS
servers break that restriction.
To improve memory usage and to make it easier to do mass-key
removal, permit combinations are cached and shared.
(5) Cell database management is overhauled to allow lighter locks to
be used and to make cell records autonomous state machines that
look after getting their own DNS records and cleaning themselves
up, in particular preventing races in acquiring and relinquishing
the fscache token for the cell.
(6) Volume caching is overhauled. The afs_vlocation record is got rid
of to simplify things and the superblock is now keyed on the cell
and the numeric volume ID only. The volume record is tied to a
superblock and normal superblock management is used to mediate
the lifetime of the volume fscache token.
(7) File server record caching is overhauled to make server records
independent of cells and volumes. A server can be in multiple
cells (in such a case, the administrator must make sure that the
VL services for all cells correctly reflect the volumes shared
between those cells).
Server records are now indexed using the UUID of the server
rather than the address since a server can have multiple
addresses.
(8) File server rotation is overhauled to handle VMOVED, VBUSY (and
similar), VOFFLINE and VNOVOL indications and to handle rotation
both of servers and addresses of those servers. The rotation will
also wait and retry if the server says it is busy.
(9) Data writeback is overhauled. Each inode no longer stores a list
of modified sections tagged with the key that authorised it in
favour of noting the modified region of a page in page->private
and storing a list of keys that made modifications in the inode.
This simplifies things and allows other keys to be used to
actually write to the server if a key that made a modification
becomes useless.
(10) Writable mmap() is implemented. This allows a kernel to be build
entirely on AFS.
Note that Pre AFS-3.4 servers are no longer supported, though this can
be added back if necessary (AFS-3.4 was released in 1998)"
* tag 'afs-next-20171113' of git://git.kernel.org/pub/scm/linux/kernel/git/dhowells/linux-fs: (35 commits)
afs: Protect call->state changes against signals
afs: Trace page dirty/clean
afs: Implement shared-writeable mmap
afs: Get rid of the afs_writeback record
afs: Introduce a file-private data record
afs: Use a dynamic port if 7001 is in use
afs: Fix directory read/modify race
afs: Trace the sending of pages
afs: Trace the initiation and completion of client calls
afs: Fix documentation on # vs % prefix in mount source specification
afs: Fix total-length calculation for multiple-page send
afs: Only progress call state at end of Tx phase from rxrpc callback
afs: Make use of the YFS service upgrade to fully support IPv6
afs: Overhaul volume and server record caching and fileserver rotation
afs: Move server rotation code into its own file
afs: Add an address list concept
afs: Overhaul cell database management
afs: Overhaul permit caching
afs: Overhaul the callback handling
afs: Rename struct afs_call server member to cm_server
...
As the page free path makes no distinction between cache hot and cold
pages, there is no real useful ordering of pages in the free list that
allocation requests can take advantage of. Juding from the users of
__GFP_COLD, it is likely that a number of them are the result of copying
other sites instead of actually measuring the impact. Remove the
__GFP_COLD parameter which simplifies a number of paths in the page
allocator.
This is potentially controversial but bear in mind that the size of the
per-cpu pagelists versus modern cache sizes means that the whole per-cpu
list can often fit in the L3 cache. Hence, there is only a potential
benefit for microbenchmarks that alloc/free pages in a tight loop. It's
even worse when THP is taken into account which has little or no chance
of getting a cache-hot page as the per-cpu list is bypassed and the
zeroing of multiple pages will thrash the cache anyway.
The truncate microbenchmarks are not shown as this patch affects the
allocation path and not the free path. A page fault microbenchmark was
tested but it showed no sigificant difference which is not surprising
given that the __GFP_COLD branches are a miniscule percentage of the
fault path.
Link: http://lkml.kernel.org/r/20171018075952.10627-9-mgorman@techsingularity.net
Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Every pagevec_init user claims the pages being released are hot even in
cases where it is unlikely the pages are hot. As no one cares about the
hotness of pages being released to the allocator, just ditch the
parameter.
No performance impact is expected as the overhead is marginal. The
parameter is removed simply because it is a bit stupid to have a useless
parameter copied everywhere.
Link: http://lkml.kernel.org/r/20171018075952.10627-6-mgorman@techsingularity.net
Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
During truncation, the mapping has already been checked for shmem and
dax so it's known that workingset_update_node is required.
This patch avoids the checks on mapping for each page being truncated.
In all other cases, a lookup helper is used to determine if
workingset_update_node() needs to be called. The one danger is that the
API is slightly harder to use as calling workingset_update_node directly
without checking for dax or shmem mappings could lead to surprises.
However, the API rarely needs to be used and hopefully the comment is
enough to give people the hint.
sparsetruncate (tiny)
4.14.0-rc4 4.14.0-rc4
oneirq-v1r1 pickhelper-v1r1
Min Time 141.00 ( 0.00%) 140.00 ( 0.71%)
1st-qrtle Time 142.00 ( 0.00%) 141.00 ( 0.70%)
2nd-qrtle Time 142.00 ( 0.00%) 142.00 ( 0.00%)
3rd-qrtle Time 143.00 ( 0.00%) 143.00 ( 0.00%)
Max-90% Time 144.00 ( 0.00%) 144.00 ( 0.00%)
Max-95% Time 147.00 ( 0.00%) 145.00 ( 1.36%)
Max-99% Time 195.00 ( 0.00%) 191.00 ( 2.05%)
Max Time 230.00 ( 0.00%) 205.00 ( 10.87%)
Amean Time 144.37 ( 0.00%) 143.82 ( 0.38%)
Stddev Time 10.44 ( 0.00%) 9.00 ( 13.74%)
Coeff Time 7.23 ( 0.00%) 6.26 ( 13.41%)
Best99%Amean Time 143.72 ( 0.00%) 143.34 ( 0.26%)
Best95%Amean Time 142.37 ( 0.00%) 142.00 ( 0.26%)
Best90%Amean Time 142.19 ( 0.00%) 141.85 ( 0.24%)
Best75%Amean Time 141.92 ( 0.00%) 141.58 ( 0.24%)
Best50%Amean Time 141.69 ( 0.00%) 141.31 ( 0.27%)
Best25%Amean Time 141.38 ( 0.00%) 140.97 ( 0.29%)
As you'd expect, the gain is marginal but it can be detected. The
differences in bonnie are all within the noise which is not surprising
given the impact on the microbenchmark.
radix_tree_update_node_t is a callback for some radix operations that
optionally passes in a private field. The only user of the callback is
workingset_update_node and as it no longer requires a mapping, the
private field is removed.
Link: http://lkml.kernel.org/r/20171018075952.10627-3-mgorman@techsingularity.net
Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Reviewed-by: Jan Kara <jack@suse.cz>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Currently we remove pages from the radix tree one by one. To speed up
page cache truncation, lock several pages at once and free them in one
go. This allows us to batch radix tree operations in a more efficient
way and also save round-trips on mapping->tree_lock. As a result we
gain about 20% speed improvement in page cache truncation.
Data from a simple benchmark timing 10000 truncates of 1024 pages (on
ext4 on ramdisk but the filesystem is barely visible in the profiles).
The range shows 1% and 95% percentiles of the measured times:
4.14-rc2 4.14-rc2 + batched truncation
248-256 209-219
249-258 209-217
248-255 211-239
248-255 209-217
247-256 210-218
[jack@suse.cz: convert delete_from_page_cache_batch() to pagevec]
Link: http://lkml.kernel.org/r/20171018111648.13714-1-jack@suse.cz
[akpm@linux-foundation.org: move struct pagevec forward declaration to top-of-file]
Link: http://lkml.kernel.org/r/20171010151937.26984-8-jack@suse.cz
Signed-off-by: Jan Kara <jack@suse.cz>
Acked-by: Mel Gorman <mgorman@suse.de>
Reviewed-by: Andi Kleen <ak@linux.intel.com>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Move checks and accounting updates from __delete_from_page_cache() into
a separate function. We will reuse it when batching page cache
truncation operations.
Link: http://lkml.kernel.org/r/20171010151937.26984-7-jack@suse.cz
Signed-off-by: Jan Kara <jack@suse.cz>
Acked-by: Mel Gorman <mgorman@suse.de>
Reviewed-by: Andi Kleen <ak@linux.intel.com>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Clearing of page->mapping makes sense in page_cache_tree_delete() as
well and it will help us with batching things this way.
Link: http://lkml.kernel.org/r/20171010151937.26984-6-jack@suse.cz
Signed-off-by: Jan Kara <jack@suse.cz>
Acked-by: Mel Gorman <mgorman@suse.de>
Reviewed-by: Andi Kleen <ak@linux.intel.com>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Move updates of various counters before page_cache_tree_delete() call.
It will be easier to batch things this way and there is no difference
whether the counters get updated before or after removal from the radix
tree.
Link: http://lkml.kernel.org/r/20171010151937.26984-5-jack@suse.cz
Signed-off-by: Jan Kara <jack@suse.cz>
Acked-by: Mel Gorman <mgorman@suse.de>
Reviewed-by: Andi Kleen <ak@linux.intel.com>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Factor out page freeing from delete_from_page_cache() into a separate
function. We will need to call the same when batching pagecache
deletion operations.
invalidate_complete_page2() and replace_page_cache_page() might want to
call this function as well however they currently don't seem to handle
THPs so it's unnecessary for them to take the hit of checking whether a
page is THP or not.
Link: http://lkml.kernel.org/r/20171010151937.26984-4-jack@suse.cz
Signed-off-by: Jan Kara <jack@suse.cz>
Acked-by: Mel Gorman <mgorman@suse.de>
Reviewed-by: Andi Kleen <ak@linux.intel.com>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
All users of pagevec_lookup() and pagevec_lookup_range() now pass
PAGEVEC_SIZE as a desired number of pages. Just drop the argument.
Link: http://lkml.kernel.org/r/20171009151359.31984-15-jack@suse.cz
Signed-off-by: Jan Kara <jack@suse.cz>
Reviewed-by: Daniel Jordan <daniel.m.jordan@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Use pagevec_lookup_range_tag() in __filemap_fdatawait_range() as it is
interested only in pages from given range. Remove unnecessary code
resulting from this.
Link: http://lkml.kernel.org/r/20171009151359.31984-11-jack@suse.cz
Signed-off-by: Jan Kara <jack@suse.cz>
Reviewed-by: Daniel Jordan <daniel.m.jordan@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Patch series "Ranged pagevec tagged lookup", v3.
In this series I provide a ranged variant of pagevec_lookup_tag() and
use it in places where it makes sense. This series removes some common
code and it also has a potential for speeding up some operations
similarly as for pagevec_lookup_range() (but for now I can think of only
artificial cases where this happens).
This patch (of 16):
Implement a variant of find_get_pages_tag() that stops iterating at
given index. Lots of users of this function (through pagevec_lookup())
actually want a range lookup and all of them are currently open-coding
this.
Also create corresponding pagevec_lookup_range_tag() function.
Link: http://lkml.kernel.org/r/20171009151359.31984-2-jack@suse.cz
Signed-off-by: Jan Kara <jack@suse.cz>
Reviewed-by: Daniel Jordan <daniel.m.jordan@oracle.com>
Cc: Bob Peterson <rpeterso@redhat.com>
Cc: Chao Yu <yuchao0@huawei.com>
Cc: David Howells <dhowells@redhat.com>
Cc: David Sterba <dsterba@suse.com>
Cc: Ilya Dryomov <idryomov@gmail.com>
Cc: Jaegeuk Kim <jaegeuk@kernel.org>
Cc: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
Cc: Steve French <sfrench@samba.org>
Cc: "Theodore Ts'o" <tytso@mit.edu>
Cc: "Yan, Zheng" <zyan@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Get rid of the afs_writeback record that kAFS is using to match keys with
writes made by that key.
Instead, keep a list of keys that have a file open for writing and/or
sync'ing and iterate through those.
Signed-off-by: David Howells <dhowells@redhat.com>
Eryu noticed that he could sometimes get a leftover error reported when
it shouldn't be on fsync with ext2 and non-journalled ext4.
The problem is that writeback_single_inode still uses filemap_fdatawait.
That picks up a previously set AS_EIO flag, which would ordinarily have
been cleared before.
Since we're mostly using this function as a replacement for
filemap_check_errors, have filemap_check_and_advance_wb_err clear AS_EIO
and AS_ENOSPC when reporting an error. That should allow the new
function to better emulate the behavior of the old with respect to these
flags.
Link: http://lkml.kernel.org/r/20170922133331.28812-1-jlayton@kernel.org
Signed-off-by: Jeff Layton <jlayton@redhat.com>
Reported-by: Eryu Guan <eguan@redhat.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Currently when mixing buffered reads and asynchronous direct writes it
is possible to end up with the situation where we have stale data in the
page cache while the new data is already written to disk. This is
permanent until the affected pages are flushed away. Despite the fact
that mixing buffered and direct IO is ill-advised it does pose a thread
for a data integrity, is unexpected and should be fixed.
Fix this by deferring completion of asynchronous direct writes to a
process context in the case that there are mapped pages to be found in
the inode. Later before the completion in dio_complete() invalidate
the pages in question. This ensures that after the completion the pages
in the written area are either unmapped, or populated with up-to-date
data. Also do the same for the iomap case which uses
iomap_dio_complete() instead.
This has a side effect of deferring the completion to a process context
for every AIO DIO that happens on inode that has pages mapped. However
since the consensus is that this is ill-advised practice the performance
implication should not be a problem.
This was based on proposal from Jeff Moyer, thanks!
Reviewed-by: Jan Kara <jack@suse.cz>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Jeff Moyer <jmoyer@redhat.com>
Signed-off-by: Lukas Czerner <lczerner@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Pull nowait read support from Al Viro:
"Support IOCB_NOWAIT for buffered reads and block devices"
* 'work.read_write' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
block_dev: support RFW_NOWAIT on block device nodes
fs: support RWF_NOWAIT for buffered reads
fs: support IOCB_NOWAIT in generic_file_buffered_read
fs: pass iocb to do_generic_file_read
Now that we have added breaks in the wait queue scan and allow bookmark
on scan position, we put this logic in the wake_up_page_bit function.
We can have very long page wait list in large system where multiple
pages share the same wait list. We break the wake up walk here to allow
other cpus a chance to access the list, and not to disable the interrupts
when traversing the list for too long. This reduces the interrupt and
rescheduling latency, and excessive page wait queue lock hold time.
[ v2: Remove bookmark_wake_function ]
Signed-off-by: Tim Chen <tim.c.chen@linux.intel.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Merge updates from Andrew Morton:
- various misc bits
- DAX updates
- OCFS2
- most of MM
* emailed patches from Andrew Morton <akpm@linux-foundation.org>: (119 commits)
mm,fork: introduce MADV_WIPEONFORK
x86,mpx: make mpx depend on x86-64 to free up VMA flag
mm: add /proc/pid/smaps_rollup
mm: hugetlb: clear target sub-page last when clearing huge page
mm: oom: let oom_reap_task and exit_mmap run concurrently
swap: choose swap device according to numa node
mm: replace TIF_MEMDIE checks by tsk_is_oom_victim
mm, oom: do not rely on TIF_MEMDIE for memory reserves access
z3fold: use per-cpu unbuddied lists
mm, swap: don't use VMA based swap readahead if HDD is used as swap
mm, swap: add sysfs interface for VMA based swap readahead
mm, swap: VMA based swap readahead
mm, swap: fix swap readahead marking
mm, swap: add swap readahead hit statistics
mm/vmalloc.c: don't reinvent the wheel but use existing llist API
mm/vmstat.c: fix wrong comment
selftests/memfd: add memfd_create hugetlbfs selftest
mm/shmem: add hugetlbfs support to memfd_create()
mm, devm_memremap_pages: use multi-order radix for ZONE_DEVICE lookups
mm/vmalloc.c: halve the number of comparisons performed in pcpu_get_vm_areas()
...
We want only pages from given range in filemap_range_has_page(),
furthermore we want at most a single page.
So use find_get_pages_range() instead of pagevec_lookup() and remove
unnecessary code.
Link: http://lkml.kernel.org/r/20170726114704.7626-10-jack@suse.cz
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Implement a variant of find_get_pages() that stops iterating at given
index. This may be substantial performance gain if the mapping is
sparse. See following commit for details. Furthermore lots of users of
this function (through pagevec_lookup()) actually want a range lookup
and all of them are currently open-coding this.
Also create corresponding pagevec_lookup_range() function.
Link: http://lkml.kernel.org/r/20170726114704.7626-4-jack@suse.cz
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Make pagevec_lookup() (and underlying find_get_pages()) update index to
the next page where iteration should continue. Most callers want this
and also pagevec_lookup_tag() already does this.
Link: http://lkml.kernel.org/r/20170726114704.7626-3-jack@suse.cz
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Now that we no longer insert struct page pointers in DAX radix trees we
can remove the special casing for DAX in page_cache_tree_insert().
This also allows us to make dax_wake_mapping_entry_waiter() local to
fs/dax.c, removing it from dax.h.
Link: http://lkml.kernel.org/r/20170724170616.25810-5-ross.zwisler@linux.intel.com
Signed-off-by: Ross Zwisler <ross.zwisler@linux.intel.com>
Suggested-by: Jan Kara <jack@suse.cz>
Reviewed-by: Jan Kara <jack@suse.cz>
Cc: "Darrick J. Wong" <darrick.wong@oracle.com>
Cc: "Theodore Ts'o" <tytso@mit.edu>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Andreas Dilger <adilger.kernel@dilger.ca>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Matthew Wilcox <mawilcox@microsoft.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Merge tag 'wberr-v4.14-1' of git://git.kernel.org/pub/scm/linux/kernel/git/jlayton/linux
Pull writeback error handling updates from Jeff Layton:
"This pile continues the work from last cycle on better tracking
writeback errors. In v4.13 we added some basic errseq_t infrastructure
and converted a few filesystems to use it.
This set continues refining that infrastructure, adds documentation,
and converts most of the other filesystems to use it. The main
exception at this point is the NFS client"
* tag 'wberr-v4.14-1' of git://git.kernel.org/pub/scm/linux/kernel/git/jlayton/linux:
ecryptfs: convert to file_write_and_wait in ->fsync
mm: remove optimizations based on i_size in mapping writeback waits
fs: convert a pile of fsync routines to errseq_t based reporting
gfs2: convert to errseq_t based writeback error reporting for fsync
fs: convert sync_file_range to use errseq_t based error-tracking
mm: add file_fdatawait_range and file_write_and_wait
fuse: convert to errseq_t based error tracking for fsync
mm: consolidate dax / non-dax checks for writeback
Documentation: add some docs for errseq_t
errseq: rename __errseq_set to errseq_set
Allow generic_file_buffered_read to bail out early instead of waiting for
the page lock or reading a page if IOCB_NOWAIT is specified.
Signed-off-by: Milosz Tanski <milosz@adfin.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Jeff Moyer <jmoyer@redhat.com>
Acked-by: Sage Weil <sage@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
And rename it to the more descriptive generic_file_buffered_read while
at it.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Commit 3510ca20ec ("Minor page waitqueue cleanups") made the page
queue code always add new waiters to the back of the queue, which helps
upcoming patches to batch the wakeups for some horrid loads where the
wait queues grow to thousands of entries.
However, I forgot about the nasrt add_page_wait_queue() special case
code that is only used by the cachefiles code. That one still continued
to add the new wait queue entries at the beginning of the list.
Fix it, because any sane batched wakeup will require that we don't
suddenly start getting new entries at the beginning of the list that we
already handled in a previous batch.
[ The current code always does the whole list while holding the lock, so
wait queue ordering doesn't matter for correctness, but even then it's
better to add later entries at the end from a fairness standpoint ]
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The "lock_page_killable()" function waits for exclusive access to the
page lock bit using the WQ_FLAG_EXCLUSIVE bit in the waitqueue entry
set.
That means that if it gets woken up, other waiters may have been
skipped.
That, in turn, means that if it sees the page being unlocked, it *must*
take that lock and return success, even if a lethal signal is also
pending.
So instead of checking for lethal signals first, we need to check for
them after we've checked the actual bit that we were waiting for. Even
if that might then delay the killing of the process.
This matches the order of the old "wait_on_bit_lock()" infrastructure
that the page locking used to use (and is still used in a few other
areas).
Note that if we still return an error after having unsuccessfully tried
to acquire the page lock, that is ok: that means that some other thread
was able to get ahead of us and lock the page, and when that other
thread then unlocks the page, the wakeup event will be repeated. So any
other pending waiters will now get properly woken up.
Fixes: 6290602709 ("mm: add PageWaiters indicating tasks are waiting for a page bit")
Cc: Nick Piggin <npiggin@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Jan Kara <jack@suse.cz>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Cc: Andi Kleen <ak@linux.intel.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Tim Chen and Kan Liang have been battling a customer load that shows
extremely long page wakeup lists. The cause seems to be constant NUMA
migration of a hot page that is shared across a lot of threads, but the
actual root cause for the exact behavior has not been found.
Tim has a patch that batches the wait list traversal at wakeup time, so
that we at least don't get long uninterruptible cases where we traverse
and wake up thousands of processes and get nasty latency spikes. That
is likely 4.14 material, but we're still discussing the page waitqueue
specific parts of it.
In the meantime, I've tried to look at making the page wait queues less
expensive, and failing miserably. If you have thousands of threads
waiting for the same page, it will be painful. We'll need to try to
figure out the NUMA balancing issue some day, in addition to avoiding
the excessive spinlock hold times.
That said, having tried to rewrite the page wait queues, I can at least
fix up some of the braindamage in the current situation. In particular:
(a) we don't want to continue walking the page wait list if the bit
we're waiting for already got set again (which seems to be one of
the patterns of the bad load). That makes no progress and just
causes pointless cache pollution chasing the pointers.
(b) we don't want to put the non-locking waiters always on the front of
the queue, and the locking waiters always on the back. Not only is
that unfair, it means that we wake up thousands of reading threads
that will just end up being blocked by the writer later anyway.
Also add a comment about the layout of 'struct wait_page_key' - there is
an external user of it in the cachefiles code that means that it has to
match the layout of 'struct wait_bit_key' in the two first members. It
so happens to match, because 'struct page *' and 'unsigned long *' end
up having the same values simply because the page flags are the first
member in struct page.
Cc: Tim Chen <tim.c.chen@linux.intel.com>
Cc: Kan Liang <kan.liang@intel.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Christopher Lameter <cl@linux.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Cc: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Marcelo added this i_size based optimization with a patch in 2004
(commitid is from the linux-history tree):
commit 765dad09b4ac101a32d87af2bb793c3060497d3c
Author: Marcelo Tosatti <marcelo.tosatti@cyclades.com>
Date: Tue Sep 7 17:51:17 2004 -0700
small wait_on_page_writeback_range() optimization
filemap_fdatawait() calls wait_on_page_writeback_range() with -1
as "end" parameter. This is not needed since we know the EOF
from the inode. Use that instead.
There may be races here, particularly with clustered or network
filesystems. It also seems like a bit of a layering violation since
we're operating on an address_space here, not an inode.
Finally, it's also questionable whether this optimization really helps
on workloads that we care about. Should we be optimizing for writeback
vs. truncate races in a codepath where we expect to wait anyway? It
doesn't seem worth the risk.
Remove this optimization from the filemap_fdatawait codepaths. This
means that filemap_fdatawait becomes a trivial wrapper around
filemap_fdatawait_range.
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Jeff Layton <jlayton@redhat.com>
Necessary now for gfs2_fsync and sync_file_range, but there will
eventually be other callers.
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Jeff Layton <jlayton@redhat.com>
We have this complex conditional copied to several places. Turn it into
a helper function.
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Jeff Layton <jlayton@redhat.com>
Nothing calls this wrapper anymore, so just remove it and rename the
old function to get rid of the double underscore prefix.
Signed-off-by: Jeff Layton <jlayton@redhat.com>
We avoid calling __mod_node_page_state(NR_FILE_PAGES) for hugetlb page
now, but it's not enough because later code doesn't handle hugetlb
properly. Actually in our testing, WARN_ON_ONCE(PageDirty(page)) at the
end of this function fires for hugetlb, which makes no sense. So we
should return immediately for hugetlb pages.
Link: http://lkml.kernel.org/r/1496305019-5493-3-git-send-email-n-horiguchi@ah.jp.nec.com
Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>
Cc: Anshuman Khandual <khandual@linux.vnet.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Merge tag 'for-linus-v4.13-2' of git://git.kernel.org/pub/scm/linux/kernel/git/jlayton/linux
Pull Writeback error handling updates from Jeff Layton:
"This pile represents the bulk of the writeback error handling fixes
that I have for this cycle. Some of the earlier patches in this pile
may look trivial but they are prerequisites for later patches in the
series.
The aim of this set is to improve how we track and report writeback
errors to userland. Most applications that care about data integrity
will periodically call fsync/fdatasync/msync to ensure that their
writes have made it to the backing store.
For a very long time, we have tracked writeback errors using two flags
in the address_space: AS_EIO and AS_ENOSPC. Those flags are set when a
writeback error occurs (via mapping_set_error) and are cleared as a
side-effect of filemap_check_errors (as you noted yesterday). This
model really sucks for userland.
Only the first task to call fsync (or msync or fdatasync) will see the
error. Any subsequent task calling fsync on a file will get back 0
(unless another writeback error occurs in the interim). If I have
several tasks writing to a file and calling fsync to ensure that their
writes got stored, then I need to have them coordinate with one
another. That's difficult enough, but in a world of containerized
setups that coordination may even not be possible.
But wait...it gets worse!
The calls to filemap_check_errors can be buried pretty far down in the
call stack, and there are internal callers of filemap_write_and_wait
and the like that also end up clearing those errors. Many of those
callers ignore the error return from that function or return it to
userland at nonsensical times (e.g. truncate() or stat()). If I get
back -EIO on a truncate, there is no reason to think that it was
because some previous writeback failed, and a subsequent fsync() will
(incorrectly) return 0.
This pile aims to do three things:
1) ensure that when a writeback error occurs that that error will be
reported to userland on a subsequent fsync/fdatasync/msync call,
regardless of what internal callers are doing
2) report writeback errors on all file descriptions that were open at
the time that the error occurred. This is a user-visible change,
but I think most applications are written to assume this behavior
anyway. Those that aren't are unlikely to be hurt by it.
3) document what filesystems should do when there is a writeback
error. Today, there is very little consistency between them, and a
lot of cargo-cult copying. We need to make it very clear what
filesystems should do in this situation.
To achieve this, the set adds a new data type (errseq_t) and then
builds new writeback error tracking infrastructure around that. Once
all of that is in place, we change the filesystems to use the new
infrastructure for reporting wb errors to userland.
Note that this is just the initial foray into cleaning up this mess.
There is a lot of work remaining here:
1) convert the rest of the filesystems in a similar fashion. Once the
initial set is in, then I think most other fs' will be fairly
simple to convert. Hopefully most of those can in via individual
filesystem trees.
2) convert internal waiters on writeback to use errseq_t for
detecting errors instead of relying on the AS_* flags. I have some
draft patches for this for ext4, but they are not quite ready for
prime time yet.
This was a discussion topic this year at LSF/MM too. If you're
interested in the gory details, LWN has some good articles about this:
https://lwn.net/Articles/718734/https://lwn.net/Articles/724307/"
* tag 'for-linus-v4.13-2' of git://git.kernel.org/pub/scm/linux/kernel/git/jlayton/linux:
btrfs: minimal conversion to errseq_t writeback error reporting on fsync
xfs: minimal conversion to errseq_t writeback error reporting
ext4: use errseq_t based error handling for reporting data writeback errors
fs: convert __generic_file_fsync to use errseq_t based reporting
block: convert to errseq_t based writeback error tracking
dax: set errors in mapping when writeback fails
Documentation: flesh out the section in vfs.txt on storing and reporting writeback errors
mm: set both AS_EIO/AS_ENOSPC and errseq_t in mapping_set_error
fs: new infrastructure for writeback error handling and reporting
lib: add errseq_t type and infrastructure for handling it
mm: don't TestClearPageError in __filemap_fdatawait_range
mm: clear AS_EIO/AS_ENOSPC when writeback initiation fails
jbd2: don't clear and reset errors after waiting on writeback
buffer: set errors in mapping at the time that the error occurs
fs: check for writeback errors after syncing out buffers in generic_file_fsync
buffer: use mapping_set_error instead of setting the flag
mm: fix mapping_set_error call in me_pagecache_dirty
Track the following reclaim counters for every memory cgroup: PGREFILL,
PGSCAN, PGSTEAL, PGACTIVATE, PGDEACTIVATE, PGLAZYFREE and PGLAZYFREED.
These values are exposed using the memory.stats interface of cgroup v2.
The meaning of each value is the same as for global counters, available
using /proc/vmstat.
Also, for consistency, rename mem_cgroup_count_vm_event() to
count_memcg_event_mm().
Link: http://lkml.kernel.org/r/1494530183-30808-1-git-send-email-guro@fb.com
Signed-off-by: Roman Gushchin <guro@fb.com>
Suggested-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Michal Hocko <mhocko@suse.com>
Acked-by: Vladimir Davydov <vdavydov.dev@gmail.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: Tejun Heo <tj@kernel.org>
Cc: Li Zefan <lizefan@huawei.com>
Cc: Balbir Singh <bsingharora@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Most filesystems currently use mapping_set_error and
filemap_check_errors for setting and reporting/clearing writeback errors
at the mapping level. filemap_check_errors is indirectly called from
most of the filemap_fdatawait_* functions and from
filemap_write_and_wait*. These functions are called from all sorts of
contexts to wait on writeback to finish -- e.g. mostly in fsync, but
also in truncate calls, getattr, etc.
The non-fsync callers are problematic. We should be reporting writeback
errors during fsync, but many places spread over the tree clear out
errors before they can be properly reported, or report errors at
nonsensical times.
If I get -EIO on a stat() call, there is no reason for me to assume that
it is because some previous writeback failed. The fact that it also
clears out the error such that a subsequent fsync returns 0 is a bug,
and a nasty one since that's potentially silent data corruption.
This patch adds a small bit of new infrastructure for setting and
reporting errors during address_space writeback. While the above was my
original impetus for adding this, I think it's also the case that
current fsync semantics are just problematic for userland. Most
applications that call fsync do so to ensure that the data they wrote
has hit the backing store.
In the case where there are multiple writers to the file at the same
time, this is really hard to determine. The first one to call fsync will
see any stored error, and the rest get back 0. The processes with open
fds may not be associated with one another in any way. They could even
be in different containers, so ensuring coordination between all fsync
callers is not really an option.
One way to remedy this would be to track what file descriptor was used
to dirty the file, but that's rather cumbersome and would likely be
slow. However, there is a simpler way to improve the semantics here
without incurring too much overhead.
This set adds an errseq_t to struct address_space, and a corresponding
one is added to struct file. Writeback errors are recorded in the
mapping's errseq_t, and the one in struct file is used as the "since"
value.
This changes the semantics of the Linux fsync implementation such that
applications can now use it to determine whether there were any
writeback errors since fsync(fd) was last called (or since the file was
opened in the case of fsync having never been called).
Note that those writeback errors may have occurred when writing data
that was dirtied via an entirely different fd, but that's the case now
with the current mapping_set_error/filemap_check_error infrastructure.
This will at least prevent you from getting a false report of success.
The new behavior is still consistent with the POSIX spec, and is more
reliable for application developers. This patch just adds some basic
infrastructure for doing this, and ensures that the f_wb_err "cursor"
is properly set when a file is opened. Later patches will change the
existing code to use this new infrastructure for reporting errors at
fsync time.
Signed-off-by: Jeff Layton <jlayton@redhat.com>
Reviewed-by: Jan Kara <jack@suse.cz>
The -EIO returned here can end up overriding whatever error is marked in
the address space, and be returned at fsync time, even when there is a
more appropriate error stored in the mapping.
Read errors are also sometimes tracked on a per-page level using
PG_error. Suppose we have a read error on a page, and then that page is
subsequently dirtied by overwriting the whole page. Writeback doesn't
clear PG_error, so we can then end up successfully writing back that
page and still return -EIO on fsync.
Worse yet, PG_error is cleared during a sync() syscall, but the -EIO
return from that is silently discarded. Any subsystem that is relying on
PG_error to report errors during fsync can easily lose writeback errors
due to this. All you need is a stray sync() call to wait for writeback
to complete and you've lost the error.
Since the handling of the PG_error flag is somewhat inconsistent across
subsystems, let's just rely on marking the address space when there are
writeback errors. Change the TestClearPageError call to ClearPageError,
and make __filemap_fdatawait_range a void return function.
Signed-off-by: Jeff Layton <jlayton@redhat.com>
filemap_write_and_wait{_range} will return an error if writeback
initiation fails, but won't clear errors in the address_space. This is
particularly problematic on DAX, as filemap_fdatawrite* is
effectively synchronous there. Ensure that we clear the AS_EIO/AS_ENOSPC
flags when filemap_fdatawrite* returns an error.
Signed-off-by: Jeff Layton <jlayton@redhat.com>
Resetting this flag is almost certainly racy, and will be problematic
with some coming changes.
Make filemap_fdatawait_keep_errors return int, but not clear the flag(s).
Have jbd2 call it instead of filemap_fdatawait and don't attempt to
re-set the error flag if it fails.
Reviewed-by: Jan Kara <jack@suse.cz>
Reviewed-by: Carlos Maiolino <cmaiolino@redhat.com>
Signed-off-by: Jeff Layton <jlayton@redhat.com>
Pull scheduler updates from Ingo Molnar:
"The main changes in this cycle were:
- Add the SYSTEM_SCHEDULING bootup state to move various scheduler
debug checks earlier into the bootup. This turns silent and
sporadically deadly bugs into nice, deterministic splats. Fix some
of the splats that triggered. (Thomas Gleixner)
- A round of restructuring and refactoring of the load-balancing and
topology code (Peter Zijlstra)
- Another round of consolidating ~20 of incremental scheduler code
history: this time in terms of wait-queue nomenclature. (I didn't
get much feedback on these renaming patches, and we can still
easily change any names I might have misplaced, so if anyone hates
a new name, please holler and I'll fix it.) (Ingo Molnar)
- sched/numa improvements, fixes and updates (Rik van Riel)
- Another round of x86/tsc scheduler clock code improvements, in hope
of making it more robust (Peter Zijlstra)
- Improve NOHZ behavior (Frederic Weisbecker)
- Deadline scheduler improvements and fixes (Luca Abeni, Daniel
Bristot de Oliveira)
- Simplify and optimize the topology setup code (Lauro Ramos
Venancio)
- Debloat and decouple scheduler code some more (Nicolas Pitre)
- Simplify code by making better use of llist primitives (Byungchul
Park)
- ... plus other fixes and improvements"
* 'sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (103 commits)
sched/cputime: Refactor the cputime_adjust() code
sched/debug: Expose the number of RT/DL tasks that can migrate
sched/numa: Hide numa_wake_affine() from UP build
sched/fair: Remove effective_load()
sched/numa: Implement NUMA node level wake_affine()
sched/fair: Simplify wake_affine() for the single socket case
sched/numa: Override part of migrate_degrades_locality() when idle balancing
sched/rt: Move RT related code from sched/core.c to sched/rt.c
sched/deadline: Move DL related code from sched/core.c to sched/deadline.c
sched/cpuset: Only offer CONFIG_CPUSETS if SMP is enabled
sched/fair: Spare idle load balancing on nohz_full CPUs
nohz: Move idle balancer registration to the idle path
sched/loadavg: Generalize "_idle" naming to "_nohz"
sched/core: Drop the unused try_get_task_struct() helper function
sched/fair: WARN() and refuse to set buddy when !se->on_rq
sched/debug: Fix SCHED_WARN_ON() to return a value on !CONFIG_SCHED_DEBUG as well
sched/wait: Disambiguate wq_entry->task_list and wq_head->task_list naming
sched/wait: Move bit_wait_table[] and related functionality from sched/core.c to sched/wait_bit.c
sched/wait: Split out the wait_bit*() APIs from <linux/wait.h> into <linux/wait_bit.h>
sched/wait: Re-adjust macro line continuation backslashes in <linux/wait.h>
...
Find out if the I/O will trigger a wait due to writeback. If yes,
return -EAGAIN.
Return -EINVAL for buffered AIO: there are multiple causes of
delay such as page locks, dirty throttling logic, page loading
from disk etc. which cannot be taken care of.
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Goldwyn Rodrigues <rgoldwyn@suse.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
filemap_range_has_page() return true if the file's mapping has
a page within the range mentioned. This function will be used
to check if a write() call will cause a writeback of previous
writes.
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Goldwyn Rodrigues <rgoldwyn@suse.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
So I've noticed a number of instances where it was not obvious from the
code whether ->task_list was for a wait-queue head or a wait-queue entry.
Furthermore, there's a number of wait-queue users where the lists are
not for 'tasks' but other entities (poll tables, etc.), in which case
the 'task_list' name is actively confusing.
To clear this all up, name the wait-queue head and entry list structure
fields unambiguously:
struct wait_queue_head::task_list => ::head
struct wait_queue_entry::task_list => ::entry
For example, this code:
rqw->wait.task_list.next != &wait->task_list
... is was pretty unclear (to me) what it's doing, while now it's written this way:
rqw->wait.head.next != &wait->entry
... which makes it pretty clear that we are iterating a list until we see the head.
Other examples are:
list_for_each_entry_safe(pos, next, &x->task_list, task_list) {
list_for_each_entry(wq, &fence->wait.task_list, task_list) {
... where it's unclear (to me) what we are iterating, and during review it's
hard to tell whether it's trying to walk a wait-queue entry (which would be
a bug), while now it's written as:
list_for_each_entry_safe(pos, next, &x->head, entry) {
list_for_each_entry(wq, &fence->wait.head, entry) {
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Rename:
wait_queue_t => wait_queue_entry_t
'wait_queue_t' was always a slight misnomer: its name implies that it's a "queue",
but in reality it's a queue *entry*. The 'real' queue is the wait queue head,
which had to carry the name.
Start sorting this out by renaming it to 'wait_queue_entry_t'.
This also allows the real structure name 'struct __wait_queue' to
lose its double underscore and become 'struct wait_queue_entry',
which is the more canonical nomenclature for such data types.
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Pull vfs fix from Al Viro:
"Braino fix for iov_iter_revert() misuse"
* 'work.iov_iter' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
fix braino in generic_file_read_iter()
Commit afddba49d1 ("fs: introduce write_begin, write_end, and
perform_write aops") introduced AOP_FLAG_UNINTERRUPTIBLE flag which was
checked in pagecache_write_begin(), but that check was removed by
4e02ed4b4a ("fs: remove prepare_write/commit_write").
Between these two commits, commit d9414774dc ("cifs: Convert cifs to
new aops.") added a check in cifs_write_begin(), but that check was soon
removed by commit a98ee8c1c7 ("[CIFS] fix regression in
cifs_write_begin/cifs_write_end").
Therefore, AOP_FLAG_UNINTERRUPTIBLE flag is checked nowhere. Let's
remove this flag. This patch has no functionality changes.
Link: http://lkml.kernel.org/r/1489294781-53494-1-git-send-email-penguin-kernel@I-love.SAKURA.ne.jp
Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Reviewed-by: Jeff Layton <jlayton@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Cc: Nick Piggin <npiggin@gmail.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Wrong sign of iov_iter_revert() argument. Unfortunately, slipped through
the testing, since most of the time we don't do anything to the iterator
afterwards and potential oops on walking the iter->iov too far backwards
is too infrequent to be easily triggered.
Add a sanity check in iov_iter_revert() to catch bugs like this one;
fortunately, the same braino hadn't happened in other callers, but we'd
better have a warning if such thing crops up.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Patch series "Properly invalidate data in the cleancache", v2.
We've noticed that after direct IO write, buffered read sometimes gets
stale data which is coming from the cleancache. The reason for this is
that some direct write hooks call call invalidate_inode_pages2[_range]()
conditionally iff mapping->nrpages is not zero, so we may not invalidate
data in the cleancache.
Another odd thing is that we check only for ->nrpages and don't check
for ->nrexceptional, but invalidate_inode_pages2[_range] also
invalidates exceptional entries as well. So we invalidate exceptional
entries only if ->nrpages != 0? This doesn't feel right.
- Patch 1 fixes direct IO writes by removing ->nrpages check.
- Patch 2 fixes similar case in invalidate_bdev().
Note: I only fixed conditional cleancache_invalidate_inode() here.
Do we also need to add ->nrexceptional check in into invalidate_bdev()?
- Patches 3-4: some optimizations.
This patch (of 4):
Some direct IO write fs hooks call invalidate_inode_pages2[_range]()
conditionally iff mapping->nrpages is not zero. This can't be right,
because invalidate_inode_pages2[_range]() also invalidate data in the
cleancache via cleancache_invalidate_inode() call. So if page cache is
empty but there is some data in the cleancache, buffered read after
direct IO write would get stale data from the cleancache.
Also it doesn't feel right to check only for ->nrpages because
invalidate_inode_pages2[_range] invalidates exceptional entries as well.
Fix this by calling invalidate_inode_pages2[_range]() regardless of
nrpages state.
Note: nfs,cifs,9p doesn't need similar fix because the never call
cleancache_get_page() (nor directly, nor via mpage_readpage[s]()), so
they are not affected by this bug.
Fixes: c515e1fd36 ("mm/fs: add hooks to support cleancache")
Link: http://lkml.kernel.org/r/20170424164135.22350-2-aryabinin@virtuozzo.com
Signed-off-by: Andrey Ryabinin <aryabinin@virtuozzo.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Acked-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Ross Zwisler <ross.zwisler@linux.intel.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Alexey Kuznetsov <kuznet@virtuozzo.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Nikolay Borisov <n.borisov.lkml@gmail.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The round_up() macro generates a couple of unnecessary instructions
in this usage:
48cd: 49 8b 47 50 mov 0x50(%r15),%rax
48d1: 48 83 e8 01 sub $0x1,%rax
48d5: 48 0d ff 0f 00 00 or $0xfff,%rax
48db: 48 83 c0 01 add $0x1,%rax
48df: 48 c1 f8 0c sar $0xc,%rax
48e3: 48 39 c3 cmp %rax,%rbx
48e6: 72 2e jb 4916 <filemap_fault+0x96>
If we change round_up() to ((x) + __round_mask(x, y)) & ~__round_mask(x, y)
then GCC can see through it and remove the mask (because that would be
dead code given the subsequent shift):
48cd: 49 8b 47 50 mov 0x50(%r15),%rax
48d1: 48 05 ff 0f 00 00 add $0xfff,%rax
48d7: 48 c1 e8 0c shr $0xc,%rax
48db: 48 39 c3 cmp %rax,%rbx
48de: 72 2e jb 490e <filemap_fault+0x8e>
But that's problematic because we'd evaluate 'y' twice. Converting
round_up into an inline function prevents it from being used in other
definitions. The easiest thing to do is just change these three usages
of round_up to use DIV_ROUND_UP. Also add an unlikely() because GCC's
heuristic is wrong in this case.
Link: http://lkml.kernel.org/r/20170207192812.5281-1-willy@infradead.org
Signed-off-by: Matthew Wilcox <mawilcox@microsoft.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Pull iov_iter updates from Al Viro:
"Cleanups that sat in -next + -stable fodder that has just missed 4.11.
There's more iov_iter work in my local tree, but I'd prefer to push
the stuff that had been in -next first"
* 'work.iov_iter' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
iov_iter: don't revert iov buffer if csum error
generic_file_read_iter(): make use of iov_iter_revert()
generic_file_direct_write(): make use of iov_iter_revert()
orangefs: use iov_iter_revert()
sctp: switch to copy_from_iter_full()
net/9p: switch to copy_from_iter_full()
switch memcpy_from_msg() to copy_from_iter_full()
rds: make use of iov_iter_revert()
We are going to split <linux/sched/signal.h> out of <linux/sched.h>, which
will have to be picked up from other headers and a couple of .c files.
Create a trivial placeholder <linux/sched/signal.h> file that just
maps to <linux/sched.h> to make this patch obviously correct and
bisectable.
Include the new header in the files that are going to need it.
Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
With rw_page, page_endio is used for completing IO on a page and it
propagates write error to the address space if the IO fails. The
problem is it accesses page->mapping directly which might be okay for
file-backed pages but it shouldn't for anonymous page. Otherwise, it
can corrupt one of field from anon_vma under us and system goes panic
randomly.
swap_writepage
bdev_writepage
ops->rw_page
I encountered the BUG during developing new zram feature and it was
really hard to figure it out because it made random crash, somtime
mmap_sem lockdep, sometime other places where places never related to
zram/zsmalloc, and not reproducible with some configuration.
When I consider how that bug is subtle and people do fast-swap test with
brd, it's worth to add stable mark, I think.
Fixes: dd6bd0d9c7 ("swap: use bdev_read_page() / bdev_write_page()")
Signed-off-by: Minchan Kim <minchan@kernel.org>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
->fault(), ->page_mkwrite(), and ->pfn_mkwrite() calls do not need to
take a vma and vmf parameter when the vma already resides in vmf.
Remove the vma parameter to simplify things.
[arnd@arndb.de: fix ARM build]
Link: http://lkml.kernel.org/r/20170125223558.1451224-1-arnd@arndb.de
Link: http://lkml.kernel.org/r/148521301778.19116.10840599906674778980.stgit@djiang5-desk3.ch.intel.com
Signed-off-by: Dave Jiang <dave.jiang@intel.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Reviewed-by: Ross Zwisler <ross.zwisler@linux.intel.com>
Cc: Theodore Ts'o <tytso@mit.edu>
Cc: Darrick J. Wong <darrick.wong@oracle.com>
Cc: Matthew Wilcox <mawilcox@microsoft.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Jan Kara <jack@suse.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Fix kernel-doc warnings in mm/filemap.c:
mm/filemap.c:993: warning: No description found for parameter '__page'
mm/filemap.c:993: warning: Excess function parameter 'page' description in '__lock_page'
Link: http://lkml.kernel.org/r/a66fe492-518c-ad6c-5f03-5e8b721fb451@infradead.org
Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
These are no longer used outside mm/filemap.c, so un-export them and
make them static where possible. These were exported specifically for
NFS use in commit a4796e37c1 ("MM: export page_wakeup functions").
Link: http://lkml.kernel.org/r/20170103182234.30141-3-npiggin@gmail.com
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Cc: Trond Myklebust <trond.myklebust@primarydata.com>
Cc: Anna Schumaker <anna.schumaker@netapp.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
do_generic_file_read() can be told to perform a large request from
userspace. If the system is under OOM and the reading task is the OOM
victim then it has an access to memory reserves and finishing the full
request can lead to the full memory depletion which is dangerous. Make
sure we rather go with a short read and allow the killed task to
terminate.
Link: http://lkml.kernel.org/r/20170201092706.9966-3-mhocko@kernel.org
Signed-off-by: Michal Hocko <mhocko@suse.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Currently in DAX if we have three read faults on the same hole address we
can end up with the following:
Thread 0 Thread 1 Thread 2
-------- -------- --------
dax_iomap_fault
grab_mapping_entry
lock_slot
<locks empty DAX entry>
dax_iomap_fault
grab_mapping_entry
get_unlocked_mapping_entry
<sleeps on empty DAX entry>
dax_iomap_fault
grab_mapping_entry
get_unlocked_mapping_entry
<sleeps on empty DAX entry>
dax_load_hole
find_or_create_page
...
page_cache_tree_insert
dax_wake_mapping_entry_waiter
<wakes one sleeper>
__radix_tree_replace
<swaps empty DAX entry with 4k zero page>
<wakes>
get_page
lock_page
...
put_locked_mapping_entry
unlock_page
put_page
<sleeps forever on the DAX
wait queue>
The crux of the problem is that once we insert a 4k zero page, all
locking from then on is done in terms of that 4k zero page and any
additional threads sleeping on the empty DAX entry will never be woken.
Fix this by waking all sleepers when we replace the DAX radix tree entry
with a 4k zero page. This will allow all sleeping threads to
successfully transition from locking based on the DAX empty entry to
locking on the 4k zero page.
With the test case reported by Xiong this happens very regularly in my
test setup, with some runs resulting in 9+ threads in this deadlocked
state. With this fix I've been able to run that same test dozens of
times in a loop without issue.
Fixes: ac401cc782 ("dax: New fault locking")
Link: http://lkml.kernel.org/r/1483479365-13607-1-git-send-email-ross.zwisler@linux.intel.com
Signed-off-by: Ross Zwisler <ross.zwisler@linux.intel.com>
Reported-by: Xiong Zhou <xzhou@redhat.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Cc: <stable@vger.kernel.org> [4.7+]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
mm/filemap.c: In function 'clear_bit_unlock_is_negative_byte':
mm/filemap.c:933:9: error: too few arguments to function 'test_bit'
return test_bit(PG_waiters);
^~~~~~~~
Fixes: b91e1302ad ('mm: optimize PageWaiters bit use for unlock_page()')
Signed-off-by: Olof Johansson <olof@lixom.net>
Brown-paper-bag-by: Linus Torvalds <dummy@duh.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
In commit 6290602709 ("mm: add PageWaiters indicating tasks are
waiting for a page bit") Nick Piggin made our page locking no longer
unconditionally touch the hashed page waitqueue, which not only helps
performance in general, but is particularly helpful on NUMA machines
where the hashed wait queues can bounce around a lot.
However, the "clear lock bit atomically and then test the waiters bit"
sequence turns out to be much more expensive than it needs to be,
because you get a nasty stall when trying to access the same word that
just got updated atomically.
On architectures where locking is done with LL/SC, this would be trivial
to fix with a new primitive that clears one bit and tests another
atomically, but that ends up not working on x86, where the only atomic
operations that return the result end up being cmpxchg and xadd. The
atomic bit operations return the old value of the same bit we changed,
not the value of an unrelated bit.
On x86, we could put the lock bit in the high bit of the byte, and use
"xadd" with that bit (where the overflow ends up not touching other
bits), and look at the other bits of the result. However, an even
simpler model is to just use a regular atomic "and" to clear the lock
bit, and then the sign bit in eflags will indicate the resulting state
of the unrelated bit #7.
So by moving the PageWaiters bit up to bit #7, we can atomically clear
the lock bit and test the waiters bit on x86 too. And architectures
with LL/SC (which is all the usual RISC suspects), the particular bit
doesn't matter, so they are fine with this approach too.
This avoids the extra access to the same atomic word, and thus avoids
the costly stall at page unlock time.
The only downside is that the interface ends up being a bit odd and
specialized: clear a bit in a byte, and test the sign bit. Nick doesn't
love the resulting name of the new primitive, but I'd rather make the
name be descriptive and very clear about the limitation imposed by
trying to work across all relevant architectures than make it be some
generic thing that doesn't make the odd semantics explicit.
So this introduces the new architecture primitive
clear_bit_unlock_is_negative_byte();
and adds the trivial implementation for x86. We have a generic
non-optimized fallback (that just does a "clear_bit()"+"test_bit(7)"
combination) which can be overridden by any architecture that can do
better. According to Nick, Power has the same hickup x86 has, for
example, but some other architectures may not even care.
All these optimizations mean that my page locking stress-test (which is
just executing a lot of small short-lived shell scripts: "make test" in
the git source tree) no longer makes our page locking look horribly bad.
Before all these optimizations, just the unlock_page() costs were just
over 3% of all CPU overhead on "make test". After this, it's down to
0.66%, so just a quarter of the cost it used to be.
(The difference on NUMA is bigger, but there this micro-optimization is
likely less noticeable, since the big issue on NUMA was not the accesses
to 'struct page', but the waitqueue accesses that were already removed
by Nick's earlier commit).
Acked-by: Nick Piggin <npiggin@gmail.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Bob Peterson <rpeterso@redhat.com>
Cc: Steven Whitehouse <swhiteho@redhat.com>
Cc: Andrew Lutomirski <luto@kernel.org>
Cc: Andreas Gruenbacher <agruenba@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Mel Gorman <mgorman@techsingularity.net>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Add a new page flag, PageWaiters, to indicate the page waitqueue has
tasks waiting. This can be tested rather than testing waitqueue_active
which requires another cacheline load.
This bit is always set when the page has tasks on page_waitqueue(page),
and is set and cleared under the waitqueue lock. It may be set when
there are no tasks on the waitqueue, which will cause a harmless extra
wakeup check that will clears the bit.
The generic bit-waitqueue infrastructure is no longer used for pages.
Instead, waitqueues are used directly with a custom key type. The
generic code was not flexible enough to have PageWaiters manipulation
under the waitqueue lock (which simplifies concurrency).
This improves the performance of page lock intensive microbenchmarks by
2-3%.
Putting two bits in the same word opens the opportunity to remove the
memory barrier between clearing the lock bit and testing the waiters
bit, after some work on the arch primitives (e.g., ensuring memory
operand widths match and cover both bits).
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Bob Peterson <rpeterso@redhat.com>
Cc: Steven Whitehouse <swhiteho@redhat.com>
Cc: Andrew Lutomirski <luto@kernel.org>
Cc: Andreas Gruenbacher <agruenba@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Mel Gorman <mgorman@techsingularity.net>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Merge more updates from Andrew Morton:
- a few misc things
- kexec updates
- DMA-mapping updates to better support networking DMA operations
- IPC updates
- various MM changes to improve DAX fault handling
- lots of radix-tree changes, mainly to the test suite. All leading up
to reimplementing the IDA/IDR code to be a wrapper layer over the
radix-tree. However the final trigger-pulling patch is held off for
4.11.
* emailed patches from Andrew Morton <akpm@linux-foundation.org>: (114 commits)
radix tree test suite: delete unused rcupdate.c
radix tree test suite: add new tag check
radix-tree: ensure counts are initialised
radix tree test suite: cache recently freed objects
radix tree test suite: add some more functionality
idr: reduce the number of bits per level from 8 to 6
rxrpc: abstract away knowledge of IDR internals
tpm: use idr_find(), not idr_find_slowpath()
idr: add ida_is_empty
radix tree test suite: check multiorder iteration
radix-tree: fix replacement for multiorder entries
radix-tree: add radix_tree_split_preload()
radix-tree: add radix_tree_split
radix-tree: add radix_tree_join
radix-tree: delete radix_tree_range_tag_if_tagged()
radix-tree: delete radix_tree_locate_item()
radix-tree: improve multiorder iterators
btrfs: fix race in btrfs_free_dummy_fs_info()
radix-tree: improve dump output
radix-tree: make radix_tree_find_next_bit more useful
...
Currently we have two different structures for passing fault information
around - struct vm_fault and struct fault_env. DAX will need more
information in struct vm_fault to handle its faults so the content of
that structure would become event closer to fault_env. Furthermore it
would need to generate struct fault_env to be able to call some of the
generic functions. So at this point I don't think there's much use in
keeping these two structures separate. Just embed into struct vm_fault
all that is needed to use it for both purposes.
Link: http://lkml.kernel.org/r/1479460644-25076-2-git-send-email-jack@suse.cz
Signed-off-by: Jan Kara <jack@suse.cz>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Ross Zwisler <ross.zwisler@linux.intel.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Jens Axboe