Commit Graph

32 Commits

Author SHA1 Message Date
Qian Cai 96bdd2bcc1 mm/frontswap: mark various intentional data races
There are a few information counters that are intentionally not protected
against increment races, so just annotate them using the data_race()
macro.

 BUG: KCSAN: data-race in __frontswap_store / __frontswap_store

 write to 0xffffffff8b7174d8 of 8 bytes by task 6396 on cpu 103:
  __frontswap_store+0x2d0/0x344
  inc_frontswap_failed_stores at mm/frontswap.c:70
  (inlined by) __frontswap_store at mm/frontswap.c:280
  swap_writepage+0x83/0xf0
  pageout+0x33e/0xae0
  shrink_page_list+0x1f57/0x2870
  shrink_inactive_list+0x316/0x880
  shrink_lruvec+0x8dc/0x1380
  shrink_node+0x317/0xd80
  do_try_to_free_pages+0x1f7/0xa10
  try_to_free_pages+0x26c/0x5e0
  __alloc_pages_slowpath+0x458/0x1290
  __alloc_pages_nodemask+0x3bb/0x450
  alloc_pages_vma+0x8a/0x2c0
  do_anonymous_page+0x170/0x700
  __handle_mm_fault+0xc9f/0xd00
  handle_mm_fault+0xfc/0x2f0
  do_page_fault+0x263/0x6f9
  page_fault+0x34/0x40

 read to 0xffffffff8b7174d8 of 8 bytes by task 6405 on cpu 47:
  __frontswap_store+0x2b9/0x344
  inc_frontswap_failed_stores at mm/frontswap.c:70
  (inlined by) __frontswap_store at mm/frontswap.c:280
  swap_writepage+0x83/0xf0
  pageout+0x33e/0xae0
  shrink_page_list+0x1f57/0x2870
  shrink_inactive_list+0x316/0x880
  shrink_lruvec+0x8dc/0x1380
  shrink_node+0x317/0xd80
  do_try_to_free_pages+0x1f7/0xa10
  try_to_free_pages+0x26c/0x5e0
  __alloc_pages_slowpath+0x458/0x1290
  __alloc_pages_nodemask+0x3bb/0x450
  alloc_pages_vma+0x8a/0x2c0
  do_anonymous_page+0x170/0x700
  __handle_mm_fault+0xc9f/0xd00
  handle_mm_fault+0xfc/0x2f0
  do_page_fault+0x263/0x6f9
  page_fault+0x34/0x40

Signed-off-by: Qian Cai <cai@lca.pw>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Marco Elver <elver@google.com>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Link: http://lkml.kernel.org/r/1581114499-5042-1-git-send-email-cai@lca.pw
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-08-14 19:56:56 -07:00
Kees Cook 3f649ab728 treewide: Remove uninitialized_var() usage
Using uninitialized_var() is dangerous as it papers over real bugs[1]
(or can in the future), and suppresses unrelated compiler warnings
(e.g. "unused variable"). If the compiler thinks it is uninitialized,
either simply initialize the variable or make compiler changes.

In preparation for removing[2] the[3] macro[4], remove all remaining
needless uses with the following script:

git grep '\buninitialized_var\b' | cut -d: -f1 | sort -u | \
	xargs perl -pi -e \
		's/\buninitialized_var\(([^\)]+)\)/\1/g;
		 s:\s*/\* (GCC be quiet|to make compiler happy) \*/$::g;'

drivers/video/fbdev/riva/riva_hw.c was manually tweaked to avoid
pathological white-space.

No outstanding warnings were found building allmodconfig with GCC 9.3.0
for x86_64, i386, arm64, arm, powerpc, powerpc64le, s390x, mips, sparc64,
alpha, and m68k.

[1] https://lore.kernel.org/lkml/20200603174714.192027-1-glider@google.com/
[2] https://lore.kernel.org/lkml/CA+55aFw+Vbj0i=1TGqCR5vQkCzWJ0QxK6CernOU6eedsudAixw@mail.gmail.com/
[3] https://lore.kernel.org/lkml/CA+55aFwgbgqhbp1fkxvRKEpzyR5J8n1vKT1VZdz9knmPuXhOeg@mail.gmail.com/
[4] https://lore.kernel.org/lkml/CA+55aFz2500WfbKXAx8s67wrm9=yVJu65TpLgN_ybYNv0VEOKA@mail.gmail.com/

Reviewed-by: Leon Romanovsky <leonro@mellanox.com> # drivers/infiniband and mlx4/mlx5
Acked-by: Jason Gunthorpe <jgg@mellanox.com> # IB
Acked-by: Kalle Valo <kvalo@codeaurora.org> # wireless drivers
Reviewed-by: Chao Yu <yuchao0@huawei.com> # erofs
Signed-off-by: Kees Cook <keescook@chromium.org>
2020-07-16 12:35:15 -07:00
Ethon Paul 404f3ecfd8 mm/frontswap: fix some typos in frontswap.c
There are some typos in comment, fix them.

s/Fortunatly/Fortunately
s/taked/taken
s/necessory/necessary
s/shink/shrink

Signed-off-by: Ethon Paul <ethp@qq.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Link: http://lkml.kernel.org/r/20200411064009.15727-1-ethp@qq.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-06-04 19:06:24 -07:00
Thomas Gleixner 7a338472f2 treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 482
Based on 1 normalized pattern(s):

  this work is licensed under the terms of the gnu gpl version 2

extracted by the scancode license scanner the SPDX license identifier

  GPL-2.0-only

has been chosen to replace the boilerplate/reference in 48 file(s).

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Allison Randal <allison@lohutok.net>
Reviewed-by: Enrico Weigelt <info@metux.net>
Cc: linux-spdx@vger.kernel.org
Link: https://lkml.kernel.org/r/20190604081204.624030236@linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2019-06-19 17:09:52 +02:00
Joe Perches 0825a6f986 mm: use octal not symbolic permissions
mm/*.c files use symbolic and octal styles for permissions.

Using octal and not symbolic permissions is preferred by many as more
readable.

https://lkml.org/lkml/2016/8/2/1945

Prefer the direct use of octal for permissions.

Done using
$ scripts/checkpatch.pl -f --types=SYMBOLIC_PERMS --fix-inplace mm/*.c
and some typing.

Before:	 $ git grep -P -w "0[0-7]{3,3}" mm | wc -l
44
After:	 $ git grep -P -w "0[0-7]{3,3}" mm | wc -l
86

Miscellanea:

o Whitespace neatening around these conversions.

Link: http://lkml.kernel.org/r/2e032ef111eebcd4c5952bae86763b541d373469.1522102887.git.joe@perches.com
Signed-off-by: Joe Perches <joe@perches.com>
Acked-by: David Rientjes <rientjes@google.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-06-15 07:55:25 +09:00
Mike Rapoport ad56b738c5 docs/vm: rename documentation files to .rst
Signed-off-by: Mike Rapoport <rppt@linux.vnet.ibm.com>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
2018-04-16 14:18:15 -06:00
Vlastimil Babka 8ea1d2a198 mm, frontswap: convert frontswap_enabled to static key
I have noticed that frontswap.h first declares "frontswap_enabled" as
extern bool variable, and then overrides it with "#define
frontswap_enabled (1)" for CONFIG_FRONTSWAP=Y or (0) when disabled.  The
bool variable isn't actually instantiated anywhere.

This all looks like an unfinished attempt to make frontswap_enabled
reflect whether a backend is instantiated.  But in the current state,
all frontswap hooks call unconditionally into frontswap.c just to check
if frontswap_ops is non-NULL.  This should at least be checked inline,
but we can further eliminate the overhead when CONFIG_FRONTSWAP is
enabled and no backend registered, using a static key that is initially
disabled, and gets enabled only upon first backend registration.

Thus, checks for "frontswap_enabled" are replaced with
"frontswap_enabled()" wrapping the static key check.  There are two
exceptions:

- xen's selfballoon_process() was testing frontswap_enabled in code guarded
  by #ifdef CONFIG_FRONTSWAP, which was effectively always true when reachable.
  The patch just removes this check. Using frontswap_enabled() does not sound
  correct here, as this can be true even without xen's own backend being
  registered.

- in SYSCALL_DEFINE2(swapon), change the check to IS_ENABLED(CONFIG_FRONTSWAP)
  as it seems the bitmap allocation cannot currently be postponed until a
  backend is registered. This means that frontswap will still have some
  memory overhead by being configured, but without a backend.

After the patch, we can expect that some functions in frontswap.c are
called only when frontswap_ops is non-NULL.  Change the checks there to
VM_BUG_ONs.  While at it, convert other BUG_ONs to VM_BUG_ONs as
frontswap has been stable for some time.

[akpm@linux-foundation.org: coding-style fixes]
Link: http://lkml.kernel.org/r/1463152235-9717-1-git-send-email-vbabka@suse.cz
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Cc: David Vrabel <david.vrabel@citrix.com>
Cc: Juergen Gross <jgross@suse.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>
2016-07-26 16:19:19 -07:00
Dan Streetman d1dc6f1bcf frontswap: allow multiple backends
Change frontswap single pointer to a singly linked list of frontswap
implementations.  Update Xen tmem implementation as register no longer
returns anything.

Frontswap only keeps track of a single implementation; any
implementation that registers second (or later) will replace the
previously registered implementation, and gets a pointer to the previous
implementation that the new implementation is expected to pass all
frontswap functions to if it can't handle the function itself.  However
that method doesn't really make much sense, as passing that work on to
every implementation adds unnecessary work to implementations; instead,
frontswap should simply keep a list of all registered implementations
and try each implementation for any function.  Most importantly, neither
of the two currently existing frontswap implementations in the kernel
actually do anything with any previous frontswap implementation that
they replace when registering.

This allows frontswap to successfully manage multiple implementations by
keeping a list of them all.

Signed-off-by: Dan Streetman <ddstreet@ieee.org>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Cc: David Vrabel <david.vrabel@citrix.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-06-24 17:49:45 -07:00
Li Haifeng a1ad28973d mm/frontswap.c: fix the condition in BUG_ON
The largest index of swap device is MAX_SWAPFILES-1.  So the type should
be less than MAX_SWAPFILES.

Signed-off-by: Haifeng Li <omycle@gmail.com>
Acked-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-12-10 17:41:08 -08:00
Weijie Yang fb993fa1a2 mm: frontswap: invalidate expired data on a dup-store failure
If a frontswap dup-store failed, it should invalidate the expired page
in the backend, or it could trigger some data corruption issue.
Such as:
 1. use zswap as the frontswap backend with writeback feature
 2. store a swap page(version_1) to entry A, success
 3. dup-store a newer page(version_2) to the same entry A, fail
 4. use __swap_writepage() write version_2 page to swapfile, success
 5. zswap do shrink, writeback version_1 page to swapfile
 6. version_2 page is overwrited by version_1, data corrupt.

This patch fixes this issue by invalidating expired data immediately
when meet a dup-store failure.

Signed-off-by: Weijie Yang <weijie.yang@samsung.com>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: Seth Jennings <sjennings@variantweb.net>
Cc: Dan Streetman <ddstreet@ieee.org>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Bob Liu <bob.liu@oracle.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-12-02 17:32:07 -08:00
Dan Streetman 18ab4d4ced swap: change swap_list_head to plist, add swap_avail_head
Originally get_swap_page() started iterating through the singly-linked
list of swap_info_structs using swap_list.next or highest_priority_index,
which both were intended to point to the highest priority active swap
target that was not full.  The first patch in this series changed the
singly-linked list to a doubly-linked list, and removed the logic to start
at the highest priority non-full entry; it starts scanning at the highest
priority entry each time, even if the entry is full.

Replace the manually ordered swap_list_head with a plist, swap_active_head.
Add a new plist, swap_avail_head.  The original swap_active_head plist
contains all active swap_info_structs, as before, while the new
swap_avail_head plist contains only swap_info_structs that are active and
available, i.e. not full.  Add a new spinlock, swap_avail_lock, to protect
the swap_avail_head list.

Mel Gorman suggested using plists since they internally handle ordering
the list entries based on priority, which is exactly what swap was doing
manually.  All the ordering code is now removed, and swap_info_struct
entries and simply added to their corresponding plist and automatically
ordered correctly.

Using a new plist for available swap_info_structs simplifies and
optimizes get_swap_page(), which no longer has to iterate over full
swap_info_structs.  Using a new spinlock for swap_avail_head plist
allows each swap_info_struct to add or remove themselves from the
plist when they become full or not-full; previously they could not
do so because the swap_info_struct->lock is held when they change
from full<->not-full, and the swap_lock protecting the main
swap_active_head must be ordered before any swap_info_struct->lock.

Signed-off-by: Dan Streetman <ddstreet@ieee.org>
Acked-by: Mel Gorman <mgorman@suse.de>
Cc: Shaohua Li <shli@fusionio.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Hugh Dickins <hughd@google.com>
Cc: Dan Streetman <ddstreet@ieee.org>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Christian Ehrhardt <ehrhardt@linux.vnet.ibm.com>
Cc: Weijie Yang <weijieut@gmail.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Bob Liu <bob.liu@oracle.com>
Cc: Paul Gortmaker <paul.gortmaker@windriver.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-06-04 16:54:07 -07:00
Dan Streetman adfab836f4 swap: change swap_info singly-linked list to list_head
The logic controlling the singly-linked list of swap_info_struct entries
for all active, i.e.  swapon'ed, swap targets is rather complex, because:

 - it stores the entries in priority order
 - there is a pointer to the highest priority entry
 - there is a pointer to the highest priority not-full entry
 - there is a highest_priority_index variable set outside the swap_lock
 - swap entries of equal priority should be used equally

this complexity leads to bugs such as: https://lkml.org/lkml/2014/2/13/181
where different priority swap targets are incorrectly used equally.

That bug probably could be solved with the existing singly-linked lists,
but I think it would only add more complexity to the already difficult to
understand get_swap_page() swap_list iteration logic.

The first patch changes from a singly-linked list to a doubly-linked list
using list_heads; the highest_priority_index and related code are removed
and get_swap_page() starts each iteration at the highest priority
swap_info entry, even if it's full.  While this does introduce unnecessary
list iteration (i.e.  Schlemiel the painter's algorithm) in the case where
one or more of the highest priority entries are full, the iteration and
manipulation code is much simpler and behaves correctly re: the above bug;
and the fourth patch removes the unnecessary iteration.

The second patch adds some minor plist helper functions; nothing new
really, just functions to match existing regular list functions.  These
are used by the next two patches.

The third patch adds plist_requeue(), which is used by get_swap_page() in
the next patch - it performs the requeueing of same-priority entries
(which moves the entry to the end of its priority in the plist), so that
all equal-priority swap_info_structs get used equally.

The fourth patch converts the main list into a plist, and adds a new plist
that contains only swap_info entries that are both active and not full.
As Mel suggested using plists allows removing all the ordering code from
swap - plists handle ordering automatically.  The list naming is also
clarified now that there are two lists, with the original list changed
from swap_list_head to swap_active_head and the new list named
swap_avail_head.  A new spinlock is also added for the new list, so
swap_info entries can be added or removed from the new list immediately as
they become full or not full.

This patch (of 4):

Replace the singly-linked list tracking active, i.e.  swapon'ed,
swap_info_struct entries with a doubly-linked list using struct
list_heads.  Simplify the logic iterating and manipulating the list of
entries, especially get_swap_page(), by using standard list_head
functions, and removing the highest priority iteration logic.

The change fixes the bug:
https://lkml.org/lkml/2014/2/13/181
in which different priority swap entries after the highest priority entry
are incorrectly used equally in pairs.  The swap behavior is now as
advertised, i.e. different priority swap entries are used in order, and
equal priority swap targets are used concurrently.

Signed-off-by: Dan Streetman <ddstreet@ieee.org>
Acked-by: Mel Gorman <mgorman@suse.de>
Cc: Shaohua Li <shli@fusionio.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Dan Streetman <ddstreet@ieee.org>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Christian Ehrhardt <ehrhardt@linux.vnet.ibm.com>
Cc: Weijie Yang <weijieut@gmail.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Bob Liu <bob.liu@oracle.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Paul Gortmaker <paul.gortmaker@windriver.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-06-04 16:54:07 -07:00
Akinobu Mita 7b57976da4 frontswap: fix incorrect zeroing and allocation size for frontswap_map
The bitmap accessed by bitops must have enough size to hold the required
numbers of bits rounded up to a multiple of BITS_PER_LONG.  And the
bitmap must not be zeroed by memset() if the number of bits cleared is
not a multiple of BITS_PER_LONG.

This fixes incorrect zeroing and allocation size for frontswap_map.  The
incorrect zeroing part doesn't cause any problem because frontswap_map
is freed just after zeroing.  But the wrongly calculated allocation size
may cause the problem.

For 32bit systems, the allocation size of frontswap_map is about twice
as large as required size.  For 64bit systems, the allocation size is
smaller than requeired if the number of bits is not a multiple of
BITS_PER_LONG.

Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-06-12 16:29:46 -07:00
Minchan Kim 4f89849da2 frontswap: get rid of swap_lock dependency
Frontswap initialization routine depends on swap_lock, which want to be
atomic about frontswap's first appearance.  IOW, frontswap is not present
and will fail all calls OR frontswap is fully functional but if new
swap_info_struct isn't registered by enable_swap_info, swap subsystem
doesn't start I/O so there is no race between init procedure and page I/O
working on frontswap.

So let's remove unnecessary swap_lock dependency.

Cc: Dan Magenheimer <dan.magenheimer@oracle.com>
Signed-off-by: Minchan Kim <minchan@kernel.org>
[v1: Rebased on my branch, reworked to work with backends loading late]
[v2: Added a check for !map]
[v3: Made the invalidate path follow the init path]
[v4: Address comments by Wanpeng Li <liwanp@linux.vnet.ibm.com>]
Signed-off-by: Konrad Rzeszutek Wilk <konrad@darnok.org>
Signed-off-by: Bob Liu <lliubbo@gmail.com>
Cc: Wanpeng Li <liwanp@linux.vnet.ibm.com>
Cc: Andor Daam <andor.daam@googlemail.com>
Cc: Florian Schmaus <fschmaus@gmail.com>
Cc: Stefan Hengelein <ilendir@googlemail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-04-30 17:04:00 -07:00
Bob Liu f066ea230a mm: frontswap: cleanup code
After allowing tmem backends to build/run as modules, frontswap_enabled
always true if defined CONFIG_FRONTSWAP.  But frontswap_test() depends on
whether backend is registered, mv it into frontswap.c using fronstswap_ops
to make the decision.

frontswap_set/clear are not used outside frontswap, so don't export them.

Signed-off-by: Bob Liu <lliubbo@gmail.com>
Cc: Wanpeng Li <liwanp@linux.vnet.ibm.com>
Cc: Andor Daam <andor.daam@googlemail.com>
Cc: Dan Magenheimer <dan.magenheimer@oracle.com>
Cc: Florian Schmaus <fschmaus@gmail.com>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Stefan Hengelein <ilendir@googlemail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-04-30 17:04:00 -07:00
Konrad Rzeszutek Wilk 1e01c968db frontswap: make frontswap_init use a pointer for the ops
This simplifies the code in the frontswap - we can get rid of the
'backend_registered' test and instead check against frontswap_ops.

[v1: Rebase on top of 703ba7fe5e (ramster->zcache move]
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Signed-off-by: Bob Liu <lliubbo@gmail.com>
Cc: Wanpeng Li <liwanp@linux.vnet.ibm.com>
Cc: Andor Daam <andor.daam@googlemail.com>
Cc: Dan Magenheimer <dan.magenheimer@oracle.com>
Cc: Florian Schmaus <fschmaus@gmail.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Stefan Hengelein <ilendir@googlemail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-04-30 17:04:00 -07:00
Dan Magenheimer 905cd0e1bf mm: frontswap: lazy initialization to allow tmem backends to build/run as modules
With the goal of allowing tmem backends (zcache, ramster, Xen tmem) to
be built/loaded as modules rather than built-in and enabled by a boot
parameter, this patch provides "lazy initialization", allowing backends
to register to frontswap even after swapon was run.  Before a backend
registers all calls to init are recorded and the creation of tmem_pools
delayed until a backend registers or until a frontswap store is
attempted.

Signed-off-by: Stefan Hengelein <ilendir@googlemail.com>
Signed-off-by: Florian Schmaus <fschmaus@gmail.com>
Signed-off-by: Andor Daam <andor.daam@googlemail.com>
Signed-off-by: Dan Magenheimer <dan.magenheimer@oracle.com>
[v1: Fixes per Seth Jennings suggestions]
[v2: Removed FRONTSWAP_HAS_.. ]
[v3: Fix up per Bob Liu <lliubbo@gmail.com> recommendations]
[v4: Fix up per Andrew's comments]
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Signed-off-by: Bob Liu <lliubbo@gmail.com>
Cc: Wanpeng Li <liwanp@linux.vnet.ibm.com>
Cc: Dan Magenheimer <dan.magenheimer@oracle.com>
Cc: Minchan Kim <minchan@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-04-30 17:04:00 -07:00
Dan Magenheimer e3483a5f3a frontswap: support exclusive gets if tmem backend is capable
Tmem, as originally specified, assumes that "get" operations
performed on persistent pools never flush the page of data out
of tmem on a successful get, waiting instead for a flush
operation.  This is intended to mimic the model of a swap
disk, where a disk read is non-destructive.  Unlike a
disk, however, freeing up the RAM can be valuable.  Over
the years that frontswap was in the review process, several
reviewers (and notably Hugh Dickins in 2010) pointed out that
this would result, at least temporarily, in two copies of the
data in RAM: one (compressed for zcache) copy in tmem,
and one copy in the swap cache.  We wondered if this could
be done differently, at least optionally.

This patch allows tmem backends to instruct the frontswap
code that this backend performs exclusive gets.  Zcache2
already contains hooks to support this feature.  Other
backends are completely unaffected unless/until they are
updated to support this feature.

While it is not clear that exclusive gets are a performance
win on all workloads at all times, this small patch allows for
experimentation by backends.

P.S. Let's not quibble about the naming of "get" vs "read" vs
"load" etc.  The naming is currently horribly inconsistent between
cleancache and frontswap and existing tmem backends, so will need
to be straightened out as a separate patch.  "Get" is used
by the tmem architecture spec, existing backends, and
all documentation and presentation material so I am
using it in this patch.

Signed-off-by: Dan Magenheimer <dan.magenheimer@oracle.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
2012-09-21 10:38:12 -04:00
Zhenzhong Duan a00bb1e9fc mm: frontswap: fix a wrong if condition in frontswap_shrink
pages_to_unuse is set to 0 to unuse all frontswap pages
But that doesn't happen since a wrong condition in frontswap_shrink
cancel it.

-v2: Add comment to explain return value of __frontswap_shrink,
as suggested by Dan Carpenter, thanks

Signed-off-by: Zhenzhong Duan <zhenzhong.duan@oracle.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
2012-09-21 10:37:45 -04:00
Seth Jennings 6b982fcf02 mm/frontswap: fix uninit'ed variable warning
Fixes uninitialized variable warning on 'type' in frontswap_shrink().
type is set before use by __frontswap_unuse_pages() called by
__frontswap_shrink() called by frontswap_shrink() before use by
try_to_unuse().

Signed-off-by: Seth Jennings <sjenning@linux.vnet.ibm.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
2012-08-13 15:41:30 -04:00
Wanpeng Li 1d00015e26 mm/frontswap: cleanup doc and comment error
Signed-off-by: Wanpeng Li <liwp.linux@gmail.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
2012-07-23 11:16:20 -04:00
Sasha Levin 3389b530a6 mm: frontswap: remove unneeded headers
Signed-off-by: Sasha Levin <levinsasha928@gmail.com>
[v1: Rebased with tracing removed]
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
2012-07-23 11:16:13 -04:00
Sasha Levin 611edfed29 mm: frontswap: split out function to clear a page out
Signed-off-by: Sasha Levin <levinsasha928@gmail.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
2012-07-19 18:51:14 -04:00
Sasha Levin f9f08103eb mm: frontswap: remove unnecessary check during initialization
The check whether frontswap is enabled or not is done in the API functions in
the frontswap header, before they are passed to the internal
double-underscored frontswap functions.

Remove the check from __frontswap_init for consistency.

Reviewed-by: Minchan Kim <minchan@kernel.org>
Signed-off-by: Sasha Levin <levinsasha928@gmail.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
2012-06-11 15:32:08 -04:00
Sasha Levin d9674dda1c mm: frontswap: make all branches of if statement in put page consistent
Currently it has a complex structure where different things are compared
at each branch. Simplify that and make both branches look similar.

Reviewed-by: Minchan Kim <minchan@kernel.org>
Signed-off-by: Sasha Levin <levinsasha928@gmail.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
2012-06-11 15:31:55 -04:00
Sasha Levin 69217b4cd0 mm: frontswap: split frontswap_shrink further to simplify locking
Split frontswap_shrink to simplify the locking in the original code.

Also, assert that the function that was split still runs under the
swap spinlock.

Signed-off-by: Sasha Levin <levinsasha928@gmail.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
2012-06-11 15:31:33 -04:00
Sasha Levin f116695a50 mm: frontswap: split out __frontswap_unuse_pages
An attempt at making frontswap_shrink shorter and more readable. This patch
splits out walking through the swap list to find an entry with enough
pages to unuse.

Also, assert that the internal __frontswap_unuse_pages is called under swap
lock, since that part of code was previously directly happen inside the lock.

Signed-off-by: Sasha Levin <levinsasha928@gmail.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
2012-06-11 15:30:57 -04:00
Sasha Levin 96253444db mm: frontswap: split out __frontswap_curr_pages
Code was duplicated in two functions, clean it up.

Also, assert that the deduplicated code runs under the swap spinlock.

Reviewed-by: Minchan Kim <minchan@kernel.org>
Signed-off-by: Sasha Levin <levinsasha928@gmail.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
2012-06-11 15:30:47 -04:00
Sasha Levin 4bb3e31ef4 mm: frontswap: trivial coding convention issues
Reviewed-by: Minchan Kim <minchan@kernel.org>
Signed-off-by: Sasha Levin <levinsasha928@gmail.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
2012-06-11 15:30:38 -04:00
Sasha Levin ef38359741 mm: frontswap: remove casting from function calls through ops structure
Removes unneeded casts.

Reviewed-by: Minchan Kim <minchan@kernel.org>
Signed-off-by: Sasha Levin <levinsasha928@gmail.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
2012-06-11 15:30:33 -04:00
Konrad Rzeszutek Wilk 165c8aed5b frontswap: s/put_page/store/g s/get_page/load
Sounds so much more natural.

Suggested-by: Andrea Arcangeli <aarcange@redhat.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
2012-05-15 11:34:08 -04:00
Dan Magenheimer 29f233cfff mm: frontswap: core frontswap functionality
This patch, 3of4, provides the core frontswap code that interfaces between
the hooks in the swap subsystem and a frontswap backend via frontswap_ops.

---
New file added: mm/frontswap.c

[v14: add support for writethrough, per suggestion by aarcange@redhat.com]
[v11: sjenning@linux.vnet.ibm.com: s/puts/failed_puts/]
[v10: sjenning@linux.vnet.ibm.com: fix debugfs calls on 32-bit]
[v9: akpm@linux-foundation.org: change "flush" to "invalidate", part 1]
[v9: akpm@linux-foundation.org: mark some statics __read_mostly]
[v9: akpm@linux-foundation.org: add clarifying comments]
[v9: akpm@linux-foundation.org: no need to loop repeating try_to_unuse]
[v9: error27@gmail.com: remove superfluous check for NULL]
[v8: rebase to 3.0-rc4]
[v8: kamezawa.hiroyu@jp.fujitsu.com: add comment to clarify find_next_to_unuse]
[v7: rebase to 3.0-rc3]
[v7: JBeulich@novell.com: use new static inlines, no-ops if not config'd]
[v6: rebase to 3.1-rc1]
[v6: lliubbo@gmail.com: use vzalloc]
[v6: lliubbo@gmail.com: fix null pointer deref if vzalloc fails]
[v6: konrad.wilk@oracl.com: various checks and code clarifications/comments]
[v4: rebase to 2.6.39]
Signed-off-by: Dan Magenheimer <dan.magenheimer@oracle.com>
Acked-by: Jan Beulich <JBeulich@novell.com>
Acked-by: Seth Jennings <sjenning@linux.vnet.ibm.com>
Cc: Jeremy Fitzhardinge <jeremy@goop.org>
Cc: Hugh Dickins <hughd@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Nitin Gupta <ngupta@vflare.org>
Cc: Matthew Wilcox <matthew@wil.cx>
Cc: Chris Mason <chris.mason@oracle.com>
Cc: Rik Riel <riel@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
[v12: Squashed s/flush/invalidate/ in]
[v15: A bit of cleanup and seperate DEBUGFS]
Signed-off-by: Konrad Wilk <konrad.wilk@oracle.com>
2012-05-15 11:34:00 -04:00