Add an option for pcpu_alloc() to support __GFP_NOWARN flag.
Currently, we always throw a warning when size or alignment
is unsupported (and also dump stack on failed allocation
requests). The warning itself is harmless since we return
NULL anyway for any failed request, which callers are
required to handle anyway. However, it becomes harmful when
panic_on_warn is set.
The rationale for the WARN() in pcpu_alloc() is that it can
be tracked when larger than supported allocation requests are
made such that allocations limits can be tweaked if warranted.
This makes sense for in-kernel users, however, there are users
of pcpu allocator where allocation size is derived from user
space requests, e.g. when creating BPF maps. In these cases,
the requests should fail gracefully without throwing a splat.
The current work-around was to check allocation size against
the upper limit of PCPU_MIN_UNIT_SIZE from call-sites for
bailing out prior to a call to pcpu_alloc() in order to
avoid throwing the WARN(). This is bad in multiple ways since
PCPU_MIN_UNIT_SIZE is an implementation detail, and having
the checks on call-sites only complicates the code for no
good reason. Thus, lets fix it generically by supporting the
__GFP_NOWARN flag that users can then use with calling the
__alloc_percpu_gfp() helper instead.
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Cc: Tejun Heo <tj@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
Unlike the SMP case, the !SMP case does not free the memory for struct
pcpu_alloc_info allocated in setup_per_cpu_areas(). And to give it a
chance of being reused by the page allocator later, align it to a page
boundary just like its size.
Signed-off-by: Nicolas Pitre <nico@linaro.org>
Acked-by: Dennis Zhou <dennisszhou@gmail.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
The iterator functions pcpu_next_md_free_region and
pcpu_next_fit_region use the block offset to determine if they have
checked the area in the prior iteration. However, this causes an issue
when the block offset is greater than subsequent block contig hints. If
within the iterator it moves to check subsequent blocks, it may fail in
the second predicate due to the block offset not being cleared. Thus,
this causes the allocator to skip over blocks leading to false failures
when allocating from the reserved chunk. While this happens in the
general case as well, it will only fail if it cannot allocate a new
chunk.
This patch resets the block offset to 0 to pass the second predicate
when checking subseqent blocks within the iterator function.
Signed-off-by: Dennis Zhou <dennisszhou@gmail.com>
Reported-and-tested-by: Luis Henriques <lhenriques@suse.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
The other patches contain a lot of information, so adding this
information in a separate patch. It adds my copyright and a brief
explanation of how the bitmap allocator works. There is a minor typo as
well in the prior explanation so that is fixed.
Signed-off-by: Dennis Zhou <dennisszhou@gmail.com>
Reviewed-by: Josef Bacik <jbacik@fb.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
The simple, and expensive, way to find a free area is to iterate over
the entire bitmap until an area is found that fits the allocation size
and alignment. This patch makes use of an iterate that find an area to
check by using the block level contig hints. It will only return an area
that can fit the size and alignment request. If the request can fit
inside a block, it returns the first_free bit to start checking from to
see if it can be fulfilled prior to the contig hint. The pcpu_alloc_area
check has a bound of a block size added in case it is wrong.
Signed-off-by: Dennis Zhou <dennisszhou@gmail.com>
Reviewed-by: Josef Bacik <jbacik@fb.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
The largest free region will either be a block level contig hint or an
aggregate over the left_free and right_free areas of blocks. This is a
much smaller set of free areas that need to be checked than a full
traverse.
Signed-off-by: Dennis Zhou <dennisszhou@gmail.com>
Reviewed-by: Josef Bacik <jbacik@fb.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
The bitmap allocator must keep metadata consistent. The easiest way is
to scan after every allocation for each affected block and the entire
chunk. This is rather expensive.
The free path can take advantage of current contig hints to prevent
scanning within the start and end block. If a scan is needed, it can
be done by scanning backwards from the start and forwards from the end
to identify the entire free area this can be combined with. The blocks
can then be updated by some basic checks rather than complete block
scans.
A chunk scan happens when the freed area makes a page free, a block
free, or spans across blocks. This is necessary as the contig hint at
this point could span across blocks. The check uses the minimum of page
size and the block size to allow for variable sized blocks. There is a
tradeoff here with not updating after every free. It is possible a
contig hint in one block can be merged with the contig hint in the next
block. This means the contig hint can be off by up to a page. However,
if the chunk's contig hint is contained in one block, the contig hint
will be accurate.
Signed-off-by: Dennis Zhou <dennisszhou@gmail.com>
Reviewed-by: Josef Bacik <jbacik@fb.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Metadata is kept per block to keep track of where the contig hints are.
Scanning can be avoided when the contig hints are not broken. In that
case, left and right contigs have to be managed manually.
This patch changes the allocation path hint updating to only scan when
contig hints are broken.
Signed-off-by: Dennis Zhou <dennisszhou@gmail.com>
Reviewed-by: Josef Bacik <jbacik@fb.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
This patch makes the contig hint starting offset optimization from the
previous patch as honest as it can be. For both chunk and block starting
offsets, make sure it keeps the starting offset with the best alignment.
The block skip optimization is added in a later patch when the
pcpu_find_block_fit iterator is swapped in.
Signed-off-by: Dennis Zhou <dennisszhou@gmail.com>
Reviewed-by: Josef Bacik <jbacik@fb.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
This patch adds chunk->contig_bits_start to keep track of the contig
hint's offset and the check to skip the chunk if it does not fit. If
the chunk's contig hint starting offset cannot satisfy an allocation,
the allocator assumes there is enough memory pressure in this chunk to
either use a different chunk or create a new one. This accepts a less
tight packing for a smoother latency curve.
Signed-off-by: Dennis Zhou <dennisszhou@gmail.com>
Reviewed-by: Josef Bacik <jbacik@fb.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
This patch adds first_bit to keep track of the first free bit in the
bitmap. This hint helps prevent scanning of fully allocated blocks.
Signed-off-by: Dennis Zhou <dennisszhou@gmail.com>
Reviewed-by: Josef Bacik <jbacik@fb.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
This patch introduces the bitmap metadata blocks and adds the skeleton
of the code that will be used to maintain these blocks. Each chunk's
bitmap is made up of full metadata blocks. These blocks maintain basic
metadata to help prevent scanning unnecssarily to update hints. Full
scanning methods are used for the skeleton and will be replaced in the
coming patches. A number of helper functions are added as well to do
conversion of pages to blocks and manage offsets. Comments will be
updated as the final version of each function is added.
There exists a relationship between PAGE_SIZE, PCPU_BITMAP_BLOCK_SIZE,
the region size, and unit_size. Every chunk's region (including offsets)
is page aligned at the beginning to preserve alignment. The end is
aligned to LCM(PAGE_SIZE, PCPU_BITMAP_BLOCK_SIZE) to ensure that the end
can fit with the populated page map which is by page and every metadata
block is fully accounted for. The unit_size is already page aligned, but
must also be aligned with PCPU_BITMAP_BLOCK_SIZE to ensure full metadata
blocks.
Signed-off-by: Dennis Zhou <dennisszhou@gmail.com>
Reviewed-by: Josef Bacik <jbacik@fb.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
The percpu memory allocator is experiencing scalability issues when
allocating and freeing large numbers of counters as in BPF.
Additionally, there is a corner case where iteration is triggered over
all chunks if the contig_hint is the right size, but wrong alignment.
This patch replaces the area map allocator with a basic bitmap allocator
implementation. Each subsequent patch will introduce new features and
replace full scanning functions with faster non-scanning options when
possible.
Implementation:
This patchset removes the area map allocator in favor of a bitmap
allocator backed by metadata blocks. The primary goal is to provide
consistency in performance and memory footprint with a focus on small
allocations (< 64 bytes). The bitmap removes the heavy memmove from the
freeing critical path and provides a consistent memory footprint. The
metadata blocks provide a bound on the amount of scanning required by
maintaining a set of hints.
In an effort to make freeing fast, the metadata is updated on the free
path if the new free area makes a page free, a block free, or spans
across blocks. This causes the chunk's contig hint to potentially be
smaller than what it could allocate by up to the smaller of a page or a
block. If the chunk's contig hint is contained within a block, a check
occurs and the hint is kept accurate. Metadata is always kept accurate
on allocation, so there will not be a situation where a chunk has a
later contig hint than available.
Evaluation:
I have primarily done testing against a simple workload of allocation of
1 million objects (2^20) of varying size. Deallocation was done by in
order, alternating, and in reverse. These numbers were collected after
rebasing ontop of a80099a152. I present the worst-case numbers here:
Area Map Allocator:
Object Size | Alloc Time (ms) | Free Time (ms)
----------------------------------------------
4B | 310 | 4770
16B | 557 | 1325
64B | 436 | 273
256B | 776 | 131
1024B | 3280 | 122
Bitmap Allocator:
Object Size | Alloc Time (ms) | Free Time (ms)
----------------------------------------------
4B | 490 | 70
16B | 515 | 75
64B | 610 | 80
256B | 950 | 100
1024B | 3520 | 200
This data demonstrates the inability for the area map allocator to
handle less than ideal situations. In the best case of reverse
deallocation, the area map allocator was able to perform within range
of the bitmap allocator. In the worst case situation, freeing took
nearly 5 seconds for 1 million 4-byte objects. The bitmap allocator
dramatically improves the consistency of the free path. The small
allocations performed nearly identical regardless of the freeing
pattern.
While it does add to the allocation latency, the allocation scenario
here is optimal for the area map allocator. The area map allocator runs
into trouble when it is allocating in chunks where the latter half is
full. It is difficult to replicate this, so I present a variant where
the pages are second half filled. Freeing was done sequentially. Below
are the numbers for this scenario:
Area Map Allocator:
Object Size | Alloc Time (ms) | Free Time (ms)
----------------------------------------------
4B | 4118 | 4892
16B | 1651 | 1163
64B | 598 | 285
256B | 771 | 158
1024B | 3034 | 160
Bitmap Allocator:
Object Size | Alloc Time (ms) | Free Time (ms)
----------------------------------------------
4B | 481 | 67
16B | 506 | 69
64B | 636 | 75
256B | 892 | 90
1024B | 3262 | 147
The data shows a parabolic curve of performance for the area map
allocator. This is due to the memmove operation being the dominant cost
with the lower object sizes as more objects are packed in a chunk and at
higher object sizes, the traversal of the chunk slots is the dominating
cost. The bitmap allocator suffers this problem as well. The above data
shows the inability to scale for the allocation path with the area map
allocator and that the bitmap allocator demonstrates consistent
performance in general.
The second problem of additional scanning can result in the area map
allocator completing in 52 minutes when trying to allocate 1 million
4-byte objects with 8-byte alignment. The same workload takes
approximately 16 seconds to complete for the bitmap allocator.
V2:
Fixed a bug in pcpu_alloc_first_chunk end_offset was setting the bitmap
using bytes instead of bits.
Added a comment to pcpu_cnt_pop_pages to explain bitmap_weight.
Signed-off-by: Dennis Zhou <dennisszhou@gmail.com>
Reviewed-by: Josef Bacik <jbacik@fb.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
The area map allocator only used a bitmap for the backing page state.
The new bitmap allocator will use bitmaps to manage the allocation
region in addition to this.
This patch generalizes the bitmap iterators so they can be reused with
the bitmap allocator.
Signed-off-by: Dennis Zhou <dennisszhou@gmail.com>
Reviewed-by: Josef Bacik <jbacik@fb.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
This patch increases the minimum allocation size of percpu memory to
4-bytes. This change will help minimize the metadata overhead
associated with the bitmap allocator. The assumption is that most
allocations will be of objects or structs greater than 2 bytes with
integers or longs being used rather than shorts.
The first chunk regions are now aligned with the minimum allocation
size. The reserved region is expected to be set as a multiple of the
minimum allocation size. The static region is aligned up and the delta
is removed from the dynamic size. This works because the dynamic size is
increased to be page aligned. If the static size is not minimum
allocation size aligned, then there must be a gap that is added to the
dynamic size. The dynamic size will never be smaller than the set value.
Signed-off-by: Dennis Zhou <dennisszhou@gmail.com>
Reviewed-by: Josef Bacik <jbacik@fb.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
pcpu_nr_empty_pop_pages is used to ensure there are a handful of free
pages around to serve atomic allocations. A new field, nr_empty_pop_pages,
is added to the pcpu_chunk struct to keep track of the number of empty
pages. This field is needed as the number of empty populated pages is
globally tracked and deltas are used to update in the bitmap allocator.
Pages that contain a hidden area are not considered to be empty. This
new field is exposed in percpu_stats.
Signed-off-by: Dennis Zhou <dennisszhou@gmail.com>
Reviewed-by: Josef Bacik <jbacik@fb.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
The populated bitmap represents the state of the pages the chunk serves.
Prior, the bitmap was marked completely used as the first chunk was
allocated and immutable. This is misleading because the first chunk may
not be completely filled. Additionally, with moving the base_addr up in
the previous patch, the population check no longer corresponds to what
was being checked.
This patch modifies the population map to be only the number of pages
the region serves and to make what it was checking correspond correctly
again. The change is to remove any misunderstanding between the size of
the populated bitmap and the actual size of it. The work function page
iterators now use nr_pages for the check rather than pcpu_unit_pages
because nr_populated is now chunk specific. Without this, the work
function would try to populate the remainder of these chunks despite it
not serving any more than nr_pages when nr_pages is set less than
pcpu_unit_pages.
Signed-off-by: Dennis Zhou <dennisszhou@gmail.com>
Reviewed-by: Josef Bacik <jbacik@fb.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
The percpu address checks for the reserved and dynamic region chunks are
now specific to each region. The address checking logic can be combined
taking advantage of the global references to the dynamic and static
region chunks.
Signed-off-by: Dennis Zhou <dennisszhou@gmail.com>
Reviewed-by: Josef Bacik <jbacik@fb.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Originally, the first chunk was served by one or two chunks, each
given a region they are responsible for. Despite this, the arithmetic
was based off of the true base_addr of the chunk making it be overly
inclusive.
This patch moves the base_addr of chunks that are responsible for the
first chunk. The base_addr must remain page aligned to keep the
address alignment correct, so it is the beginning of the region served
page aligned down. start_offset holds where the region served begins
from this new base_addr.
The corresponding percpu address checks are modified to be more specific
as a result. The first chunk considers only the dynamic region and both
first chunk and reserved chunk checks ignore the static region. The
static region addresses should never be passed into the allocator. There
is no impact here besides distinguishing the first chunk and making the
checks specific.
The percpu pointer to physical address is left intact as addresses are
not given out in the non-allocated portion of percpu memory.
nr_pages is added to pcpu_chunk to keep track of the size of the entire
region served containing both start_offset and end_offset. This variable
will be used to manage the bitmap allocator.
Signed-off-by: Dennis Zhou <dennisszhou@gmail.com>
Reviewed-by: Josef Bacik <jbacik@fb.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
There is no need to have the static chunk and dynamic chunk be named
separately as the allocations are sequential. This preemptively solves
the misnomer problem with the base_addrs being moved up in the following
patch. It also removes a ternary operation deciding the first chunk.
Signed-off-by: Dennis Zhou <dennisszhou@gmail.com>
Reviewed-by: Josef Bacik <jbacik@fb.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
The area map allocator manages the first chunk area by hiding all but
the region it is responsible for serving in the area map. To align this
with the populated page bitmap, end_offset is introduced to keep track
of the delta to end page aligned. The area map is appended with the
page aligned end when necessary to be in line with how the bitmap
allocator requires the ending to be aligned with the LCM of PAGE_SIZE
and the size of each bitmap block. percpu_stats is updated to ignore
this region when present.
Signed-off-by: Dennis Zhou <dennisszhou@gmail.com>
Reviewed-by: Josef Bacik <jbacik@fb.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Create a common allocator for first chunk initialization,
pcpu_alloc_first_chunk. Comments for this function will be added in a
later patch once the bitmap allocator is added.
Signed-off-by: Dennis Zhou <dennisszhou@gmail.com>
Reviewed-by: Josef Bacik <jbacik@fb.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
There is logic for setting variables in the static chunk init code that
could be consolidated with the dynamic chunk init code. This combines
this logic to setup for combining the allocation paths. reserved_size is
used as the conditional as a dynamic region will always exist.
Signed-off-by: Dennis Zhou <dennisszhou@gmail.com>
Reviewed-by: Josef Bacik <jbacik@fb.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Prior this variable was used to manage statistics when the first chunk
had a reserved region. The previous patch introduced start_offset to
keep track of the offset by value rather than boolean. Therefore,
has_reserved can be removed.
Signed-off-by: Dennis Zhou <dennisszhou@gmail.com>
Reviewed-by: Josef Bacik <jbacik@fb.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
The reserved chunk arithmetic uses a global variable
pcpu_reserved_chunk_limit that is set in the first chunk init code to
hide a portion of the area map. The bitmap allocator to come will
eventually move the base_addr up and require both the reserved chunk
and static chunk to maintain this offset. pcpu_reserved_chunk_limit is
removed and start_offset is added.
The first chunk that is circulated and is pcpu_first_chunk serves the
dynamic region, the region following the reserved region. The reserved
chunk address check will temporarily use the first chunk to identify its
address range. A following patch will increase the base_addr and remove
this. If there is no reserved chunk, this will check the static region
and return false because those values should never be passed into the
allocator.
Lastly, when linking in the first chunk, make sure to count the right
free region for the number of empty populated pages.
Signed-off-by: Dennis Zhou <dennisszhou@gmail.com>
Reviewed-by: Josef Bacik <jbacik@fb.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
The first chunk is handled as a special case as it is composed of the
static, reserved, and dynamic regions. The code handles each case
individually. The next several patches will merge these code paths and
lay the foundation for the bitmap allocator.
This patch modifies logic to enforce that a dynamic region exists and
changes the area map to account for that. This brings the logic closer
to the dynamic chunk's init logic.
Signed-off-by: Dennis Zhou <dennisszhou@gmail.com>
Reviewed-by: Josef Bacik <jbacik@fb.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
The header comment for percpu memory is a little hard to parse and is
not super clear about how the first chunk is managed. This adds a
little more clarity to the situation.
There is also quite a bit of tricky logic in the pcpu_build_alloc_info.
This adds a restructure of a comment to add a little more information.
Unfortunately, you will still have to piece together a handful of other
comments too, but should help direct you to the meaningful comments.
Signed-off-by: Dennis Zhou <dennisszhou@gmail.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Percpu memory holds a minimum threshold of pages that are populated
in order to serve atomic percpu memory requests. This change makes it
easier to verify that there are a minimum number of populated pages
lying around.
Signed-off-by: Dennis Zhou <dennisszhou@gmail.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
From 4a42ecc735cff0015cc73c3d87edede631f4b885 Mon Sep 17 00:00:00 2001
From: Dennis Zhou <dennisz@fb.com>
Date: Wed, 21 Jun 2017 08:07:15 -0700
Add error message to out of space failure for atomic allocations in
percpu allocation path to fix -Wmaybe-uninitialized.
Signed-off-by: Dennis Zhou <dennisz@fb.com>
Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Tejun Heo <tj@kernel.org>
Add support for tracepoints to the following events: chunk allocation,
chunk free, area allocation, area free, and area allocation failure.
This should let us replay percpu memory requests and evaluate
corresponding decisions.
Signed-off-by: Dennis Zhou <dennisz@fb.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
There is limited visibility into the use of percpu memory leaving us
unable to reason about correctness of parameters and overall use of
percpu memory. These counters and statistics aim to help understand
basic statistics about percpu memory such as number of allocations over
the lifetime, allocation sizes, and fragmentation.
New Config: PERCPU_STATS
Signed-off-by: Dennis Zhou <dennisz@fb.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Migrates pcpu_chunk definition and a few percpu static variables to an
internal header file from mm/percpu.c. These will be used with debugfs
to expose statistics about percpu memory improving visibility regarding
allocations and fragmentation.
Signed-off-by: Dennis Zhou <dennisz@fb.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Add a missing lockdep_assert_held for pcpu_lock to improve consistency
and safety throughout mm/percpu.c.
Signed-off-by: Dennis Zhou <dennisz@fb.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Moving pcpu_base_addr to this section comes from PaX where it's part of
KERNEXEC. This extends it to the rest of the globals only written by the
init code.
Signed-off-by: Daniel Micay <danielmicay@gmail.com>
Acked-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Tejun Heo <tj@kernel.org>
Since commit 383776fa75 ("locking/lockdep: Handle statically initialized
PER_CPU locks properly") we try to collapse per-cpu locks into a single
class by giving them all the same key. For this key we choose the canonical
address of the per-cpu object, which would be the offset into the per-cpu
area.
This has two problems:
- there is a case where we run !0 lock->key through static_obj() and
expect this to pass; it doesn't for canonical pointers.
- 0 is a valid canonical address.
Cure both issues by redefining the canonical address as the address of the
per-cpu variable on the boot CPU.
Since I didn't want to rely on CPU0 being the boot-cpu, or even existing at
all, track the boot CPU in a variable.
Fixes: 383776fa75 ("locking/lockdep: Handle statically initialized PER_CPU locks properly")
Reported-by: kernel test robot <fengguang.wu@intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Tested-by: Borislav Petkov <bp@suse.de>
Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: linux-mm@kvack.org
Cc: wfg@linux.intel.com
Cc: kernel test robot <fengguang.wu@intel.com>
Cc: LKP <lkp@01.org>
Link: http://lkml.kernel.org/r/20170320114108.kbvcsuepem45j5cr@hirez.programming.kicks-ass.net
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
If a PER_CPU struct which contains a spin_lock is statically initialized
via:
DEFINE_PER_CPU(struct foo, bla) = {
.lock = __SPIN_LOCK_UNLOCKED(bla.lock)
};
then lockdep assigns a seperate key to each lock because the logic for
assigning a key to statically initialized locks is to use the address as
the key. With per CPU locks the address is obvioulsy different on each CPU.
That's wrong, because all locks should have the same key.
To solve this the following modifications are required:
1) Extend the is_kernel/module_percpu_addr() functions to hand back the
canonical address of the per CPU address, i.e. the per CPU address
minus the per CPU offset.
2) Check the lock address with these functions and if the per CPU check
matches use the returned canonical address as the lock key, so all per
CPU locks have the same key.
3) Move the static_obj(key) check into look_up_lock_class() so this check
can be avoided for statically initialized per CPU locks. That's
required because the canonical address fails the static_obj(key) check
for obvious reasons.
Reported-by: Mike Galbraith <efault@gmx.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
[ Merged Dan's fixups for !MODULES and !SMP into this patch. ]
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Dan Murphy <dmurphy@ti.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/20170227143736.pectaimkjkan5kow@linutronix.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Update to pcpu_nr_empty_pop_pages in pcpu_alloc() is currently done
without holding pcpu_lock. This can lead to bad updates to the variable.
Add missing lock calls.
Fixes: b539b87fed ("percpu: implmeent pcpu_nr_empty_pop_pages and chunk->nr_populated")
Signed-off-by: Tahsin Erdogan <tahsin@google.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: stable@vger.kernel.org # v3.18+
Fix typos and add the following to the scripts/spelling.txt:
followings||following
While we are here, add a missing colon in the boilerplate in DT binding
documents. The "you SoC" in allwinner,sunxi-pinctrl.txt was fixed as
well.
I reworded "as the followings:" to "as follows:" for
drivers/usb/gadget/udc/renesas_usb3.c.
Link: http://lkml.kernel.org/r/1481573103-11329-32-git-send-email-yamada.masahiro@socionext.com
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Pull percpu update from Tejun Heo:
"This includes just one patch to reject non-power-of-2 alignments and
trigger warning. Interestingly, this actually caught a bug in XEN
ARM64"
* 'for-4.10' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/percpu:
percpu: ensure the requested alignment is power of two
As shown by pcpu_build_alloc_info(), the number of units within a percpu
group is deduced by rounding up the number of CPUs within the group to
@upa boundary/ Therefore, the number of CPUs isn't equal to the units's
if it isn't aligned to @upa normally. However, pcpu_page_first_chunk()
uses BUG_ON() to assert that one number is equal to the other roughly,
so a panic is maybe triggered by the BUG_ON() incorrectly.
In order to fix this issue, the number of CPUs is rounded up then
compared with units's and the BUG_ON() is replaced with a warning and
return of an error code as well, to keep system alive as much as
possible.
Link: http://lkml.kernel.org/r/57FCF07C.2020103@zoho.com
Signed-off-by: zijun_hu <zijun_hu@htc.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Christoph Lameter <cl@linux.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The percpu allocator expectedly assumes that the requested alignment
is power of two but hasn't been veryfing the input. If the specified
alignment isn't power of two, the allocator can malfunction. Add the
sanity check.
The following is detailed analysis of the effects of alignments which
aren't power of two.
The alignment must be a even at least since the LSB of a chunk->map
element is used as free/in-use flag of a area; besides, the alignment
must be a power of 2 too since ALIGN() doesn't work well for other
alignment always but is adopted by pcpu_fit_in_area(). IOW, the
current allocator only works well for a power of 2 aligned area
allocation.
See below opposite example for why an odd alignment doesn't work.
Let's assume area [16, 36) is free but its previous one is in-use, we
want to allocate a @size == 8 and @align == 7 area. The larger area
[16, 36) is split to three areas [16, 21), [21, 29), [29, 36)
eventually. However, due to the usage for a chunk->map element, the
actual offset of the aim area [21, 29) is 21 but is recorded in
relevant element as 20; moreover, the residual tail free area [29,
36) is mistook as in-use and is lost silently
Unlike macro roundup(), ALIGN(x, a) doesn't work if @a isn't a power
of 2 for example, roundup(10, 6) == 12 but ALIGN(10, 6) == 10, and
the latter result isn't desired obviously.
tj: Code style and patch description updates.
Signed-off-by: zijun_hu <zijun_hu@htc.com>
Suggested-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Tejun Heo <tj@kernel.org>
in order to ensure the percpu group areas within a chunk aren't
distributed too sparsely, pcpu_embed_first_chunk() goes to error handling
path when a chunk spans over 3/4 VMALLOC area, however, during the error
handling, it forget to free the memory allocated for all percpu groups by
going to label @out_free other than @out_free_areas.
it will cause memory leakage issue if the rare scene really happens, in
order to fix the issue, we check chunk spanned area immediately after
completing memory allocation for all percpu groups, we go to label
@out_free_areas to free the memory then return if the checking is failed.
in order to verify the approach, we dump all memory allocated then
enforce the jump then dump all memory freed, the result is okay after
checking whether we free all memory we allocate in this function.
BTW, The approach is chosen after thinking over the below scenes
- we don't go to label @out_free directly to fix this issue since we
maybe free several allocated memory blocks twice
- the aim of jumping after pcpu_setup_first_chunk() is bypassing free
usable memory other than handling error, moreover, the function does
not return error code in any case, it either panics due to BUG_ON()
or return 0.
Signed-off-by: zijun_hu <zijun_hu@htc.com>
Tested-by: zijun_hu <zijun_hu@htc.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
pcpu_embed_first_chunk() calculates the range a percpu chunk spans into
@max_distance and uses it to ensure that a chunk is not too big compared
to the total vmalloc area. However, during calculation, it used incorrect
top address by adding a unit size to the highest group's base address.
This can make the calculated max_distance slightly smaller than the actual
distance although given the scale of values involved the error is very
unlikely to have an actual impact.
Fix this issue by adding the group's size instead of a unit size.
BTW, The type of variable max_distance is changed from size_t to unsigned
long too based on below consideration:
- type unsigned long usually have same width with IP core registers and
can be applied at here very well
- make @max_distance type consistent with the operand calculated against
it such as @ai->groups[i].base_offset and macro VMALLOC_TOTAL
- type unsigned long is more universal then size_t, size_t is type defined
to unsigned int or unsigned long among various ARCHs usually
Signed-off-by: zijun_hu <zijun_hu@htc.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
For non-atomic allocations, pcpu_alloc() can try to extend the area
map synchronously after dropping pcpu_lock; however, the extension
wasn't synchronized against chunk destruction and the chunk might get
freed while extension is in progress.
This patch fixes the bug by putting most of non-atomic allocations
under pcpu_alloc_mutex to synchronize against pcpu_balance_work which
is responsible for async chunk management including destruction.
Signed-off-by: Tejun Heo <tj@kernel.org>
Reported-and-tested-by: Alexei Starovoitov <alexei.starovoitov@gmail.com>
Reported-by: Vlastimil Babka <vbabka@suse.cz>
Reported-by: Sasha Levin <sasha.levin@oracle.com>
Cc: stable@vger.kernel.org # v3.18+
Fixes: 1a4d76076c ("percpu: implement asynchronous chunk population")
Atomic allocations can trigger async map extensions which is serviced
by chunk->map_extend_work. pcpu_balance_work which is responsible for
destroying idle chunks wasn't synchronizing properly against
chunk->map_extend_work and may end up freeing the chunk while the work
item is still in flight.
This patch fixes the bug by rolling async map extension operations
into pcpu_balance_work.
Signed-off-by: Tejun Heo <tj@kernel.org>
Reported-and-tested-by: Alexei Starovoitov <alexei.starovoitov@gmail.com>
Reported-by: Vlastimil Babka <vbabka@suse.cz>
Reported-by: Sasha Levin <sasha.levin@oracle.com>
Cc: stable@vger.kernel.org # v3.18+
Fixes: 9c824b6a17 ("percpu: make sure chunk->map array has available space")
Use the normal mechanism to make the logging output consistently
"percpu:" instead of a mix of "PERCPU:" and "percpu:"
Signed-off-by: Joe Perches <joe@perches.com>
Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Most of the mm subsystem uses pr_<level> so make it consistent.
Miscellanea:
- Realign arguments
- Add missing newline to format
- kmemleak-test.c has a "kmemleak: " prefix added to the
"Kmemleak testing" logging message via pr_fmt
Signed-off-by: Joe Perches <joe@perches.com>
Acked-by: Tejun Heo <tj@kernel.org> [percpu]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Kernel style prefers a single string over split strings when the string is
'user-visible'.
Miscellanea:
- Add a missing newline
- Realign arguments
Signed-off-by: Joe Perches <joe@perches.com>
Acked-by: Tejun Heo <tj@kernel.org> [percpu]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
There are a mixture of pr_warning and pr_warn uses in mm. Use pr_warn
consistently.
Miscellanea:
- Coalesce formats
- Realign arguments
Signed-off-by: Joe Perches <joe@perches.com>
Acked-by: Tejun Heo <tj@kernel.org> [percpu]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
There are many locations that do
if (memory_was_allocated_by_vmalloc)
vfree(ptr);
else
kfree(ptr);
but kvfree() can handle both kmalloc()ed memory and vmalloc()ed memory
using is_vmalloc_addr(). Unless callers have special reasons, we can
replace this branch with kvfree(). Please check and reply if you found
problems.
Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Acked-by: Michal Hocko <mhocko@suse.com>
Acked-by: Jan Kara <jack@suse.com>
Acked-by: Russell King <rmk+kernel@arm.linux.org.uk>
Reviewed-by: Andreas Dilger <andreas.dilger@intel.com>
Acked-by: "Rafael J. Wysocki" <rjw@rjwysocki.net>
Acked-by: David Rientjes <rientjes@google.com>
Cc: "Luck, Tony" <tony.luck@intel.com>
Cc: Oleg Drokin <oleg.drokin@intel.com>
Cc: Boris Petkov <bp@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The original assignment is a little redundent.
Signed-off-by: Baoquan He <bhe@redhat.com>
Acked-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Beginning at commit d52d3997f8 ("ipv6: Create percpu rt6_info"), the
following INFO splat is logged:
===============================
[ INFO: suspicious RCU usage. ]
4.1.0-rc7-next-20150612 #1 Not tainted
-------------------------------
kernel/sched/core.c:7318 Illegal context switch in RCU-bh read-side critical section!
other info that might help us debug this:
rcu_scheduler_active = 1, debug_locks = 0
3 locks held by systemd/1:
#0: (rtnl_mutex){+.+.+.}, at: [<ffffffff815f0c8f>] rtnetlink_rcv+0x1f/0x40
#1: (rcu_read_lock_bh){......}, at: [<ffffffff816a34e2>] ipv6_add_addr+0x62/0x540
#2: (addrconf_hash_lock){+...+.}, at: [<ffffffff816a3604>] ipv6_add_addr+0x184/0x540
stack backtrace:
CPU: 0 PID: 1 Comm: systemd Not tainted 4.1.0-rc7-next-20150612 #1
Hardware name: TOSHIBA TECRA A50-A/TECRA A50-A, BIOS Version 4.20 04/17/2014
Call Trace:
dump_stack+0x4c/0x6e
lockdep_rcu_suspicious+0xe7/0x120
___might_sleep+0x1d5/0x1f0
__might_sleep+0x4d/0x90
kmem_cache_alloc+0x47/0x250
create_object+0x39/0x2e0
kmemleak_alloc_percpu+0x61/0xe0
pcpu_alloc+0x370/0x630
Additional backtrace lines are truncated. In addition, the above splat
is followed by several "BUG: sleeping function called from invalid
context at mm/slub.c:1268" outputs. As suggested by Martin KaFai Lau,
these are the clue to the fix. Routine kmemleak_alloc_percpu() always
uses GFP_KERNEL for its allocations, whereas it should follow the gfp
from its callers.
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Reviewed-by: Kamalesh Babulal <kamalesh@linux.vnet.ibm.com>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: Larry Finger <Larry.Finger@lwfinger.net>
Cc: Martin KaFai Lau <kafai@fb.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Christoph Lameter <cl@linux-foundation.org>
Cc: <stable@vger.kernel.org> [3.18+]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
printk and friends can now format bitmaps using '%*pb[l]'. cpumask
and nodemask also provide cpumask_pr_args() and nodemask_pr_args()
respectively which can be used to generate the two printf arguments
necessary to format the specified cpu/nodemask.
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Christoph Lameter <cl@linux-foundation.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The unit_map[] array has "nr_cpu_ids" number of elements. It's
allocated a few lines earlier in the function. So this test should be
>= instead of >.
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
When @gfp is specified, the percpu allocator is interested in whether
it contains all of GFP_KERNEL or not. If it does, the normal
allocation path is taken; otherwise, the atomic allocation path.
Unfortunately, pcpu_alloc() was incorrectly testing for whether @gfp
contains any part of GFP_KERNEL.
Fix it by testing "(gfp & GFP_KERNEL) != GFP_KERNEL" instead of
"!(gfp & GFP_KERNEL)" to decide whether the allocation should be
atomic or not.
Signed-off-by: Tejun Heo <tj@kernel.org>
This reverts commit 3189eddbca ("percpu: free percpu allocation info for
uniprocessor system").
The commit causes a hang with a crisv32 image. This may be an architecture
problem, but at least for now the revert is necessary to be able to boot a
crisv32 image.
Cc: Tejun Heo <tj@kernel.org>
Cc: Honggang Li <enjoymindful@gmail.com>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Tejun Heo <tj@kernel.org>
Fixes: 3189eddbca ("percpu: free percpu allocation info for uniprocessor system")
Cc: stable@vger.kernel.org # Please don't apply 3189eddbca
While updating locking, b38d08f318 ("percpu: restructure locking")
broke pcpu_create_chunk() creation path in pcpu_alloc(). It returns
without releasing pcpu_alloc_mutex. Fix it.
Signed-off-by: Tejun Heo <tj@kernel.org>
Reported-by: Julia Lawall <julia.lawall@lip6.fr>
The percpu allocator now supports atomic allocations by only
allocating from already populated areas but the mechanism to ensure
that there's adequate amount of populated areas was missing.
This patch expands pcpu_balance_work so that in addition to freeing
excess free chunks it also populates chunks to maintain an adequate
level of populated areas. pcpu_alloc() schedules pcpu_balance_work if
the amount of free populated areas is too low or after an atomic
allocation failure.
* PERPCU_DYNAMIC_RESERVE is increased by two pages to account for
PCPU_EMPTY_POP_PAGES_LOW.
* pcpu_async_enabled is added to gate both async jobs -
chunk->map_extend_work and pcpu_balance_work - so that we don't end
up scheduling them while the needed subsystems aren't up yet.
Signed-off-by: Tejun Heo <tj@kernel.org>
pcpu_reclaim_work will also be used to populate chunks asynchronously.
Rename it to pcpu_balance_work in preparation. pcpu_reclaim() is
renamed to pcpu_balance_workfn() and some of its local variables are
renamed too.
This is pure rename.
Signed-off-by: Tejun Heo <tj@kernel.org>
pcpu_nr_empty_pop_pages counts the number of empty populated pages
across all chunks and chunk->nr_populated counts the number of
populated pages in a chunk. Both will be used to implement pre/async
population for atomic allocations.
pcpu_chunk_[de]populated() are added to update chunk->populated,
chunk->nr_populated and pcpu_nr_empty_pop_pages together. All
successful chunk [de]populations should be followed by the
corresponding pcpu_chunk_[de]populated() calls.
Signed-off-by: Tejun Heo <tj@kernel.org>
An allocation attempt may require extending chunk->map array which
requires GFP_KERNEL context which isn't available for atomic
allocations. This patch ensures that chunk->map array usually keeps
some amount of available space by directly allocating buffer space
during GFP_KERNEL allocations and scheduling async extension during
atomic ones. This should make atomic allocation failures from map
space exhaustion rare.
Signed-off-by: Tejun Heo <tj@kernel.org>
Now that pcpu_alloc_area() can allocate only from populated areas,
it's easy to add atomic allocation support to [__]alloc_percpu().
Update pcpu_alloc() so that it accepts @gfp and skips all the blocking
operations and allocates only from the populated areas if @gfp doesn't
contain GFP_KERNEL. New interface functions [__]alloc_percpu_gfp()
are added.
While this means that atomic allocations are possible, this isn't
complete yet as there's no mechanism to ensure that certain amount of
populated areas is kept available and atomic allocations may keep
failing under certain conditions.
Signed-off-by: Tejun Heo <tj@kernel.org>
The next patch will conditionalize the population block in
pcpu_alloc() which will end up making a rather large indentation
change obfuscating the actual logic change. This patch puts the block
under "if (true)" so that the next patch can avoid indentation
changes. The defintions of the local variables which are used only in
the block are moved into the block.
This patch is purely cosmetic.
Signed-off-by: Tejun Heo <tj@kernel.org>
Update pcpu_alloc_area() so that it can skip unpopulated areas if the
new parameter @pop_only is true. This is implemented by a new
function, pcpu_fit_in_area(), which determines the amount of head
padding considering the alignment and populated state.
@pop_only is currently always false but this will be used to implement
atomic allocation.
Signed-off-by: Tejun Heo <tj@kernel.org>
At first, the percpu allocator required a sleepable context for both
alloc and free paths and used pcpu_alloc_mutex to protect everything.
Later, pcpu_lock was introduced to protect the index data structure so
that the free path can be invoked from atomic contexts. The
conversion only updated what's necessary and left most of the
allocation path under pcpu_alloc_mutex.
The percpu allocator is planned to add support for atomic allocation
and this patch restructures locking so that the coverage of
pcpu_alloc_mutex is further reduced.
* pcpu_alloc() now grab pcpu_alloc_mutex only while creating a new
chunk and populating the allocated area. Everything else is now
protected soley by pcpu_lock.
After this change, multiple instances of pcpu_extend_area_map() may
race but the function already implements sufficient synchronization
using pcpu_lock.
This also allows multiple allocators to arrive at new chunk
creation. To avoid creating multiple empty chunks back-to-back, a
new chunk is created iff there is no other empty chunk after
grabbing pcpu_alloc_mutex.
* pcpu_lock is now held while modifying chunk->populated bitmap.
After this, all data structures are protected by pcpu_lock.
Signed-off-by: Tejun Heo <tj@kernel.org>
Previously, pcpu_[de]populate_chunk() were called with the range which
may contain multiple target regions in it and
pcpu_[de]populate_chunk() iterated over the regions. This has the
benefit of batching up cache flushes for all the regions; however,
we're planning to add more bookkeeping logic around [de]population to
support atomic allocations and this delegation of iterations gets in
the way.
This patch moves the region iterations out of
pcpu_[de]populate_chunk() into its callers - pcpu_alloc() and
pcpu_reclaim() - so that we can later add logic to track more states
around them. This change may make cache and tlb flushes more frequent
but multi-region [de]populations are rare anyway and if this actually
becomes a problem, it's not difficult to factor out cache flushes as
separate callbacks which are directly invoked from percpu.c.
Signed-off-by: Tejun Heo <tj@kernel.org>
percpu-vm and percpu-km implement separate versions of
pcpu_[de]populate_chunk() and some part which is or should be common
are currently in the specific implementations. Make the following
changes.
* Allocate area clearing is moved from the pcpu_populate_chunk()
implementations to pcpu_alloc(). This makes percpu-km's version
noop.
* Quick exit tests in pcpu_[de]populate_chunk() of percpu-vm are moved
to their respective callers so that they are applied to percpu-km
too. This doesn't make any meaningful difference as both functions
are noop for percpu-km; however, this is more consistent and will
help implementing atomic allocation support.
Signed-off-by: Tejun Heo <tj@kernel.org>
Currently, only SMP system free the percpu allocation info.
Uniprocessor system should free it too. For example, one x86 UML
virtual machine with 256MB memory, UML kernel wastes one page memory.
Signed-off-by: Honggang Li <enjoymindful@gmail.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: stable@vger.kernel.org
pcpu_chunk_struct_size = sizeof(struct pcpu_chunk) +
BITS_TO_LONGS(pcpu_unit_pages) * sizeof(unsigned long)
It hardly could be ever bigger than PAGE_SIZE even for large-scale machine,
but for consistency with its couterpart pcpu_mem_zalloc(),
use pcpu_mem_free() instead.
Commit b4916cb17c ("percpu: make pcpu_free_chunk() use
pcpu_mem_free() instead of kfree()") addressed this problem, but
missed this one.
tj: commit message updated
Signed-off-by: Jianyu Zhan <nasa4836@gmail.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Fixes: 099a19d91c ("percpu: allow limited allocation before slab is online)
Cc: stable@vger.kernel.org
During pcpu_alloc_area(), we might merge the current head with the
previous block. Since we have calculated the max_contig using the
size of previous block before we skip it, and now we update the size
of previous block, so we should renew the max_contig.
Signed-off-by: Jianyu Zhan <nasa4836@gmail.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
723ad1d90b ("percpu: store offsets instead of lengths in ->map[]")
updated percpu area allocator to use the lowest bit, instead of sign,
to signify whether the area is occupied and forced min align to 2;
unfortunately, it forgot to force the allocation size to be even
causing malfunctions for the very rare odd-sized allocations.
Always force the allocations to be even sized.
tj: Wrote patch description.
Original-patch-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Tejun Heo <tj@kernel.org>
If we know that first N areas are all in use, we can obviously skip
them when searching for a free one. And that kind of hint is very
easy to maintain.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Tejun Heo <tj@kernel.org>
Current code keeps +-length for each area in chunk->map[]. It has
several unpleasant consequences:
* even if we know that first 50 areas are all in use, allocation
still needs to go through all those areas just to sum their sizes, just
to get the offset of free one.
* freeing needs to find the array entry refering to the area
in question; again, the need to sum the sizes until we reach the offset
we are interested in. Note that offsets are monotonous, so simple
binary search would do here.
New data representation: array of <offset,in-use flag> pairs.
Each pair is represented by one int - we use offset|1 for <offset, in use>
and offset for <offset, free> (we make sure that all offsets are even).
In the end we put a sentry entry - <total size, in use>. The first
entry is <0, flag>; it would be possible to store together the flag
for Nth area and offset for N+1st, but that leads to much hairier code.
In other words, where the old variant would have
4, -8, -4, 4, -12, 100
(4 bytes free, 8 in use, 4 in use, 4 free, 12 in use, 100 free) we store
<0,0>, <4,1>, <12,1>, <16,0>, <20,1>, <32,0>, <132,1>
i.e.
0, 5, 13, 16, 21, 32, 133
This commit switches to new data representation and takes care of a couple
of low-hanging fruits in free_pcpu_area() - one is the switch to binary
search, another is not doing two memmove() when one would do. Speeding
the alloc side up (by keeping track of how many areas in the beginning are
known to be all in use) also becomes possible - that'll be done in the next
commit.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Tejun Heo <tj@kernel.org>
... and simplify the results a bit. Makes the next step easier
to deal with - we will be changing the data representation for
chunk->map[] and it's easier to do if the code in question is
not split between pcpu_alloc_area() and pcpu_split_block().
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Tejun Heo <tj@kernel.org>
Merge first patch-bomb from Andrew Morton:
- a couple of misc things
- inotify/fsnotify work from Jan
- ocfs2 updates (partial)
- about half of MM
* emailed patches from Andrew Morton <akpm@linux-foundation.org>: (117 commits)
mm/migrate: remove unused function, fail_migrate_page()
mm/migrate: remove putback_lru_pages, fix comment on putback_movable_pages
mm/migrate: correct failure handling if !hugepage_migration_support()
mm/migrate: add comment about permanent failure path
mm, page_alloc: warn for non-blockable __GFP_NOFAIL allocation failure
mm: compaction: reset scanner positions immediately when they meet
mm: compaction: do not mark unmovable pageblocks as skipped in async compaction
mm: compaction: detect when scanners meet in isolate_freepages
mm: compaction: reset cached scanner pfn's before reading them
mm: compaction: encapsulate defer reset logic
mm: compaction: trace compaction begin and end
memcg, oom: lock mem_cgroup_print_oom_info
sched: add tracepoints related to NUMA task migration
mm: numa: do not automatically migrate KSM pages
mm: numa: trace tasks that fail migration due to rate limiting
mm: numa: limit scope of lock for NUMA migrate rate limiting
mm: numa: make NUMA-migrate related functions static
lib/show_mem.c: show num_poisoned_pages when oom
mm/hwpoison: add '#' to hwpoison_inject
mm/memblock: use WARN_ONCE when MAX_NUMNODES passed as input parameter
...
Switch to memblock interfaces for early memory allocator instead of
bootmem allocator. No functional change in beahvior than what it is in
current code from bootmem users points of view.
Archs already converted to NO_BOOTMEM now directly use memblock
interfaces instead of bootmem wrappers build on top of memblock. And
the archs which still uses bootmem, these new apis just fallback to
exiting bootmem APIs.
Signed-off-by: Santosh Shilimkar <santosh.shilimkar@ti.com>
Cc: "Rafael J. Wysocki" <rjw@sisk.pl>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Christoph Lameter <cl@linux-foundation.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Grygorii Strashko <grygorii.strashko@ti.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Paul Walmsley <paul@pwsan.com>
Cc: Pavel Machek <pavel@ucw.cz>
Cc: Russell King <linux@arm.linux.org.uk>
Cc: Tejun Heo <tj@kernel.org>
Cc: Tony Lindgren <tony@atomide.com>
Cc: Yinghai Lu <yinghai@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
vmalloc already gives a useful macro to calculate the total vmalloc
size. Use it.
Signed-off-by: Laura Abbott <lauraa@codeaurora.org>
Signed-off-by: Tejun Heo <tj@kernel.org>
If memory allocation of in pcpu_embed_first_chunk() fails, the
allocated memory is not released correctly. In the release loop also
the non-allocated elements are released which leads to the following
kernel BUG on systems with very little memory:
[ 0.000000] kernel BUG at mm/bootmem.c:307!
[ 0.000000] illegal operation: 0001 [#1] PREEMPT SMP DEBUG_PAGEALLOC
[ 0.000000] Modules linked in:
[ 0.000000] CPU: 0 PID: 0 Comm: swapper Not tainted 3.10.0 #22
[ 0.000000] task: 0000000000a20ae0 ti: 0000000000a08000 task.ti: 0000000000a08000
[ 0.000000] Krnl PSW : 0400000180000000 0000000000abda7a (__free+0x116/0x154)
[ 0.000000] R:0 T:1 IO:0 EX:0 Key:0 M:0 W:0 P:0 AS:0 CC:0 PM:0 EA:3
...
[ 0.000000] [<0000000000abdce2>] mark_bootmem_node+0xde/0xf0
[ 0.000000] [<0000000000abdd9c>] mark_bootmem+0xa8/0x118
[ 0.000000] [<0000000000abcbba>] pcpu_embed_first_chunk+0xe7a/0xf0c
[ 0.000000] [<0000000000abcc96>] setup_per_cpu_areas+0x4a/0x28c
To fix the problem now only allocated elements are released. This then
leads to the correct kernel panic:
[ 0.000000] Kernel panic - not syncing: Failed to initialize percpu areas.
...
[ 0.000000] Call Trace:
[ 0.000000] ([<000000000011307e>] show_trace+0x132/0x150)
[ 0.000000] [<0000000000113160>] show_stack+0xc4/0xd4
[ 0.000000] [<00000000007127dc>] dump_stack+0x74/0xd8
[ 0.000000] [<00000000007123fe>] panic+0xea/0x264
[ 0.000000] [<0000000000b14814>] setup_per_cpu_areas+0x5c/0x28c
tj: Flipped if conditional so that it doesn't need "continue".
Signed-off-by: Michael Holzheu <holzheu@linux.vnet.ibm.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
commit 099a19d9('allow limited allocation before slab is online') made
pcpu_alloc_chunk() use pcpu_mem_zalloc() but forgot to update
pcpu_free_chunk() accordingly. This doesn't cause any immediate
problema, but fix it for consistency.
tj: commit message updated
Signed-off-by: Joonsoo Kim <js1304@gmail.com>
Cc: Christoph Lameter <cl@linux.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Kmemleak tracks the percpu allocations via a specific API and the
originally allocated areas must be removed from kmemleak (via
kmemleak_free). The code was already doing this for SMP systems.
Reported-by: Sami Liedes <sami.liedes@iki.fi>
Cc: Tejun Heo <tj@kernel.org>
Cc: Christoph Lameter <cl@linux-foundation.org>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
pcpu_embed_first_chunk() allocates memory for each node, copies percpu
data and frees unused portions of it before proceeding to the next
group. This assumes that allocations for different nodes doesn't
overlap; however, depending on memory topology, the bootmem allocator
may end up allocating memory from a different node than the requested
one which may overlap with the portion freed from one of the previous
percpu areas. This leads to percpu groups for different nodes
overlapping which is a serious bug.
This patch separates out copy & partial free from the allocation loop
such that all allocations are complete before partial frees happen.
This also fixes overlapping frees which could happen on allocation
failure path - out_free_areas path frees whole groups but the groups
could have portions freed at that point.
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: stable@vger.kernel.org
Reported-by: "Pavel V. Panteleev" <pp_84@mail.ru>
Tested-by: "Pavel V. Panteleev" <pp_84@mail.ru>
LKML-Reference: <E1SNhwY-0007ui-V7.pp_84-mail-ru@f220.mail.ru>
pcpu_dump_alloc_info() was printing continued lines without KERN_CONT.
Use it.
Signed-off-by: Tejun Heo <tj@kernel.org>
Reported-by: Kay Sievers <kay.sievers@vrfy.org>
Main features:
- Handle percpu memory allocations (only scanning them, not actually
reporting).
- Memory hotplug support.
Usability improvements:
- Show the origin of early allocations.
- Report previously found leaks even if kmemleak has been disabled by
some error.
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Merge tag 'kmemleak' of git://git.kernel.org/pub/scm/linux/kernel/git/cmarinas/linux
Kmemleak patches
Main features:
- Handle percpu memory allocations (only scanning them, not actually
reporting).
- Memory hotplug support.
Usability improvements:
- Show the origin of early allocations.
- Report previously found leaks even if kmemleak has been disabled by
some error.
* tag 'kmemleak' of git://git.kernel.org/pub/scm/linux/kernel/git/cmarinas/linux:
kmemleak: Add support for memory hotplug
kmemleak: Handle percpu memory allocation
kmemleak: Report previously found leaks even after an error
kmemleak: When the early log buffer is exceeded, report the actual number
kmemleak: Show where early_log issues come from
per_cpu_ptr_to_phys() incorrectly rounds up its result for non-kmalloc
case to the page boundary, which is bogus for any non-page-aligned
address.
This affects the only in-tree user of this function - sysfs handler
for per-cpu 'crash_notes' physical address. The trouble is that the
crash_notes per-cpu variable is not page-aligned:
crash_notes = 0xc08e8ed4
PER-CPU OFFSET VALUES:
CPU 0: 3711f000
CPU 1: 37129000
CPU 2: 37133000
CPU 3: 3713d000
So, the per-cpu addresses are:
crash_notes on CPU 0: f7a07ed4 => phys 36b57ed4
crash_notes on CPU 1: f7a11ed4 => phys 36b4ded4
crash_notes on CPU 2: f7a1bed4 => phys 36b43ed4
crash_notes on CPU 3: f7a25ed4 => phys 36b39ed4
However, /sys/devices/system/cpu/cpu*/crash_notes says:
/sys/devices/system/cpu/cpu0/crash_notes: 36b57000
/sys/devices/system/cpu/cpu1/crash_notes: 36b4d000
/sys/devices/system/cpu/cpu2/crash_notes: 36b43000
/sys/devices/system/cpu/cpu3/crash_notes: 36b39000
As you can see, all values are rounded down to a page
boundary. Consequently, this is where kexec sets up the NOTE segments,
and thus where the secondary kernel is looking for them. However, when
the first kernel crashes, it saves the notes to the unaligned
addresses, where they are not found.
Fix it by adding offset_in_page() to the translated page address.
-tj: Combined Eugene's and Petr's commit messages.
Signed-off-by: Eugene Surovegin <ebs@ebshome.net>
Signed-off-by: Tejun Heo <tj@kernel.org>
Reported-by: Petr Tesarik <ptesarik@suse.cz>
Cc: stable@kernel.org
This patch adds kmemleak callbacks from the percpu allocator, reducing a
number of false positives caused by kmemleak not scanning such memory
blocks. The percpu chunks are never reported as leaks because of current
kmemleak limitations with the __percpu pointer not pointing directly to
the actual chunks.
Reported-by: Huajun Li <huajun.li.lee@gmail.com>
Acked-by: Christoph Lameter <cl@gentwo.org>
Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Add comments about current per_cpu_ptr_to_phys implementation to
explain why the logic is more complicated than necessary.
-tj: relocated comment into kerneldoc comment
Signed-off-by: Dave Young <dyoung@redhat.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Percpu allocator recorded the cpus which map to the first and last
units in pcpu_first/last_unit_cpu respectively and used them to
determine the address range of a chunk - e.g. it assumed that the
first unit has the lowest address in a chunk while the last unit has
the highest address.
This simply isn't true. Groups in a chunk can have arbitrary positive
or negative offsets from the previous one and there is no guarantee
that the first unit occupies the lowest offset while the last one the
highest.
Fix it by actually comparing unit offsets to determine cpus occupying
the lowest and highest offsets. Also, rename pcu_first/last_unit_cpu
to pcpu_low/high_unit_cpu to avoid confusion.
The chunk address range is used to flush cache on vmalloc area
map/unmap and decide whether a given address is in the first chunk by
per_cpu_ptr_to_phys() and the bug was discovered by invalid
per_cpu_ptr_to_phys() translation for crash_note.
Kudos to Dave Young for tracking down the problem.
Signed-off-by: Tejun Heo <tj@kernel.org>
Reported-by: WANG Cong <xiyou.wangcong@gmail.com>
Reported-by: Dave Young <dyoung@redhat.com>
Tested-by: Dave Young <dyoung@redhat.com>
LKML-Reference: <4EC21F67.10905@redhat.com>
Cc: stable @kernel.org
Currently pcpu_mem_alloc() is implemented always return zeroed memory.
So rename it to make user like pcpu_get_pages_and_bitmap() know don't
reinit it.
Signed-off-by: Bob Liu <lliubbo@gmail.com>
Reviewed-by: Pekka Enberg <penberg@kernel.org>
Reviewed-by: Michal Hocko <mhocko@suse.cz>
Signed-off-by: Tejun Heo <tj@kernel.org>
* 'for-2.6.40' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/percpu:
percpu: Unify input section names
percpu: Avoid extra NOP in percpu_cmpxchg16b_double
percpu: Cast away printk format warning
percpu: Always align percpu output section to PAGE_SIZE
Fix up fairly trivial conflict in arch/x86/include/asm/percpu.h as per Tejun
On 32-bit systems which don't happen to implicitly define or cast
VMALLOC_START and/or VMALLOC_END to long in their arch headers, the
printk in the percpu code will cause a warning to be emitted:
mm/percpu.c: In function 'pcpu_embed_first_chunk':
mm/percpu.c:1648: warning: format '%lx' expects type 'long unsigned int',
but argument 3 has type 'unsigned int'
So add an explicit cast to unsigned long here.
Signed-off-by: Mike Frysinger <vapier@gentoo.org>
Signed-off-by: Tejun Heo <tj@kernel.org>
per_cpu_ptr_to_phys() uses VMALLOC_START and VMALLOC_END to determine if an
address is in the vmalloc() region or not. This is incorrect on NOMMU as
there is no real vmalloc() capability (vmalloc() is emulated by kmalloc()).
The correct way to do this is to use is_vmalloc_addr(). This encapsulates the
vmalloc() region test in MMU mode and just returns 0 in NOMMU mode.
On FRV in NOMMU mode, the percpu compilation fails without this patch:
mm/percpu.c: In function 'per_cpu_ptr_to_phys':
mm/percpu.c:1011: error: 'VMALLOC_START' undeclared (first use in this function)
mm/percpu.c:1011: error: (Each undeclared identifier is reported only once
mm/percpu.c:1011: error: for each function it appears in.)
mm/percpu.c:1012: error: 'VMALLOC_END' undeclared (first use in this function)
mm/percpu.c:1018: warning: control reaches end of non-void function
Signed-off-by: David Howells <dhowells@redhat.com>
Percpu allocator honors alignment request upto PAGE_SIZE and both the
percpu addresses in the percpu address space and the translated kernel
addresses should be aligned accordingly. The calculation of the
former depends on the alignment of percpu output section in the kernel
image.
The linker script macros PERCPU_VADDR() and PERCPU() are used to
define this output section and the latter takes @align parameter.
Several architectures are using @align smaller than PAGE_SIZE breaking
percpu memory alignment.
This patch removes @align parameter from PERCPU(), renames it to
PERCPU_SECTION() and makes it always align to PAGE_SIZE. While at it,
add PCPU_SETUP_BUG_ON() checks such that alignment problems are
reliably detected and remove percpu alignment comment recently added
in workqueue.c as the condition would trigger BUG way before reaching
there.
For um, this patch raises the alignment of percpu area. As the area
is in .init, there shouldn't be any noticeable difference.
This problem was discovered by David Howells while debugging boot
failure on mn10300.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Mike Frysinger <vapier@gentoo.org>
Cc: uclinux-dist-devel@blackfin.uclinux.org
Cc: David Howells <dhowells@redhat.com>
Cc: Jeff Dike <jdike@addtoit.com>
Cc: user-mode-linux-devel@lists.sourceforge.net
* 'for-2.6.38' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/percpu: (30 commits)
gameport: use this_cpu_read instead of lookup
x86: udelay: Use this_cpu_read to avoid address calculation
x86: Use this_cpu_inc_return for nmi counter
x86: Replace uses of current_cpu_data with this_cpu ops
x86: Use this_cpu_ops to optimize code
vmstat: User per cpu atomics to avoid interrupt disable / enable
irq_work: Use per cpu atomics instead of regular atomics
cpuops: Use cmpxchg for xchg to avoid lock semantics
x86: this_cpu_cmpxchg and this_cpu_xchg operations
percpu: Generic this_cpu_cmpxchg() and this_cpu_xchg support
percpu,x86: relocate this_cpu_add_return() and friends
connector: Use this_cpu operations
xen: Use this_cpu_inc_return
taskstats: Use this_cpu_ops
random: Use this_cpu_inc_return
fs: Use this_cpu_inc_return in buffer.c
highmem: Use this_cpu_xx_return() operations
vmstat: Use this_cpu_inc_return for vm statistics
x86: Support for this_cpu_add, sub, dec, inc_return
percpu: Generic support for this_cpu_add, sub, dec, inc_return
...
Fixed up conflicts: in arch/x86/kernel/{apic/nmi.c, apic/x2apic_uv_x.c, process.c}
as per Tejun.
Now that percpu allocator is mostly stable, there is no reason to
print alloc information with KERN_INFO and clutter the boot messages.
Switch it to KERN_DEBUG.
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Mike Travis <travis@sgi.com>
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/percpu:
percpu: update comments to reflect that percpu allocations are always zero-filled
percpu: Optimize __get_cpu_var()
x86, percpu: Optimize this_cpu_ptr
percpu: clear memory allocated with the km allocator
percpu: fix build breakage on s390 and cleanup build configuration tests
percpu: use percpu allocator on UP too
percpu: reduce PCPU_MIN_UNIT_SIZE to 32k
vmalloc: pcpu_get/free_vm_areas() aren't needed on UP
Fixed up trivial conflicts in include/linux/percpu.h
pcpu_first/last_unit_cpu are used to track which cpu has the first and
last units assigned. This in turn is used to determine the span of a
chunk for man/unmap cache flushes and whether an address belongs to
the first chunk or not in per_cpu_ptr_to_phys().
When the number of possible CPUs isn't power of two, a chunk may
contain unassigned units towards the end of a chunk. The logic to
determine pcpu_last_unit_cpu was incorrect when there was an unused
unit at the end of a chunk. It failed to ignore the unused unit and
assigned the unused marker NR_CPUS to pcpu_last_unit_cpu.
This was discovered through kdump failure which was caused by
malfunctioning per_cpu_ptr_to_phys() on a kvm setup with 50 possible
CPUs by CAI Qian.
Signed-off-by: Tejun Heo <tj@kernel.org>
Reported-by: CAI Qian <caiqian@redhat.com>
Cc: stable@kernel.org
Commit bbddff05 (percpu: use percpu allocator on UP too) incorrectly
excluded pcpu_build_alloc_info() on SMP configurations which use
generic setup_per_cpu_area() like s390. The config ifdefs are
becoming confusing. Fix and clean it up by,
* Move pcpu_build_alloc_info() right on top of its two users -
pcpu_{embed|page}_first_chunk() which are already in CONFIG_SMP
block.
* Define BUILD_{EMBED|PAGE}_FIRST_CHUNK which indicate whether each
first chunk function needs to be included and use them to control
inclusion of the three functions to reduce confusion.
Signed-off-by: Tejun Heo <tj@kernel.org>
Reported-by: Sachin Sant <sachinp@in.ibm.com>
On UP, percpu allocations were redirected to kmalloc. This has the
following problems.
* For certain amount of allocations (determined by
PERCPU_DYNAMIC_EARLY_SLOTS and PERCPU_DYNAMIC_EARLY_SIZE), percpu
allocator can be used before the usual kernel memory allocator is
brought online. On SMP, this is used to initialize the kernel
memory allocator.
* percpu allocator honors alignment upto PAGE_SIZE but kmalloc()
doesn't. For example, workqueue makes use of larger alignments for
cpu_workqueues.
Currently, users of percpu allocators need to handle UP differently,
which is somewhat fragile and ugly. Other than small amount of
memory, there isn't much to lose by enabling percpu allocator on UP.
It can simply use kernel memory based chunk allocation which was added
for SMP archs w/o MMUs.
This patch removes mm/percpu_up.c, builds mm/percpu.c on UP too and
makes UP build use percpu-km. As percpu addresses and kernel
addresses are always identity mapped and static percpu variables don't
need any special treatment, nothing is arch dependent and mm/percpu.c
implements generic setup_per_cpu_areas() for UP.
Signed-off-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Christoph Lameter <cl@linux-foundation.org>
Acked-by: Pekka Enberg <penberg@cs.helsinki.fi>
When pcpu_build_alloc_info() searches best_upa value, it ignores current value
if the number of waste units exceeds 1/3 of the number of total cpus. But the
comment on the code says that it will ignore if wastage is over 25%.
Modify the comment.
Signed-off-by: Namhyung Kim <namhyung@gmail.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
The original code did not free the old map. This patch fixes it.
tj: use @old as memcpy source instead of @chunk->map, and indentation
and description update
Signed-off-by: Huang Shijie <shijie8@gmail.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: stable@kernel.org
This patch updates percpu allocator such that it can serve limited
amount of allocation before slab comes online. This is primarily to
allow slab to depend on working percpu allocator.
Two parameters, PERCPU_DYNAMIC_EARLY_SIZE and SLOTS, determine how
much memory space and allocation map slots are reserved. If this
reserved area is exhausted, WARN_ON_ONCE() will trigger and allocation
will fail till slab comes online.
The following changes are made to implement early alloc.
* pcpu_mem_alloc() now checks slab_is_available()
* Chunks are allocated using pcpu_mem_alloc()
* Init paths make sure ai->dyn_size is at least as large as
PERCPU_DYNAMIC_EARLY_SIZE.
* Initial alloc maps are allocated in __initdata and copied to
kmalloc'd areas once slab is online.
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Christoph Lameter <cl@linux-foundation.org>
In pcpu_build_alloc_info() and pcpu_embed_first_chunk(), @dyn_size was
ssize_t, -1 meant auto-size, 0 forced 0 and positive meant minimum
size. There's no use case for forcing 0 and the upcoming early alloc
support always requires non-zero dynamic size. Make @dyn_size always
mean minimum dyn_size.
While at it, make pcpu_build_alloc_info() static which doesn't have
any external caller as suggested by David Rientjes.
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: David Rientjes <rientjes@google.com>
per_cpu_ptr_to_phys() determines whether the passed in @addr belongs
to the first_chunk or not by just matching the address against the
address range of the base unit (unit0, used by cpu0). When an adress
from another cpu was passed in, it will always determine that the
address doesn't belong to the first chunk even when it does. This
makes the function return a bogus physical address which may lead to
crash.
This problem was discovered by Cliff Wickman while investigating a
crash during kdump on a SGI UV system.
Signed-off-by: Tejun Heo <tj@kernel.org>
Reported-by: Cliff Wickman <cpw@sgi.com>
Tested-by: Cliff Wickman <cpw@sgi.com>
Cc: stable@kernel.org
Fix the following two trivial bugs in pcpu_build_alloc_info()
* we should memset group_cnt to 0 by size of group_cnt, not size of
group_map (both are of the same size, so the bug isn't dangerous)
* we can delete useless variable group_cnt_max.
Signed-off-by: Pavel V. Panteleev <pp_84@mail.ru>
Signed-off-by: Tejun Heo <tj@kernel.org>
Implement an alternate percpu chunk management based on kernel memeory
for nommu SMP architectures. Instead of mapping into vmalloc area,
chunks are allocated as a contiguous kernel memory using
alloc_pages(). As such, percpu allocator on nommu will have the
following restrictions.
* It can't fill chunks on-demand page-by-page. It has to allocate
each chunk fully upfront.
* It can't support sparse chunk for NUMA configurations. SMP w/o mmu
is crazy enough. Let's hope no one does NUMA w/o mmu. :-P
* If chunk size isn't power-of-two multiple of PAGE_SIZE, the
unaligned amount will be wasted on each chunk. So, archs which use
this better align chunk size.
For instructions on how to use this, read the comment on top of
mm/percpu-km.c.
Signed-off-by: Tejun Heo <tj@kernel.org>
Reviewed-by: David Howells <dhowells@redhat.com>
Cc: Graff Yang <graff.yang@gmail.com>
Cc: Sonic Zhang <sonic.adi@gmail.com>
Separate out and move chunk management (creation/desctruction and
[de]population) code into percpu-vm.c which is included by percpu.c
and compiled together. The interface for chunk management is defined
as follows.
* pcpu_populate_chunk - populate the specified range of a chunk
* pcpu_depopulate_chunk - depopulate the specified range of a chunk
* pcpu_create_chunk - create a new chunk
* pcpu_destroy_chunk - destroy a chunk, always preceded by full depop
* pcpu_addr_to_page - translate address to physical address
* pcpu_verify_alloc_info - check alloc_info is acceptable during init
Other than wrapping vmalloc_to_page() inside pcpu_addr_to_page() and
dummy pcpu_verify_alloc_info() implementation, this patch only moves
code around. This separation is to allow alternate chunk management
implementation.
Signed-off-by: Tejun Heo <tj@kernel.org>
Reviewed-by: David Howells <dhowells@redhat.com>
Cc: Graff Yang <graff.yang@gmail.com>
Cc: Sonic Zhang <sonic.adi@gmail.com>
Make the following misc preparations for percpu nommu support.
* Remove refernces to vmalloc in common comments as nommu percpu won't
use it.
* Rename chunk->vms to chunk->data and make it void *. Its use is
determined by chunk management implementation.
* Relocate utility functions and add __maybe_unused to functions which
might not be used by different chunk management implementations.
This patch doesn't cause any functional change. This is to allow
alternate chunk management implementation for percpu nommu support.
Signed-off-by: Tejun Heo <tj@kernel.org>
Reviewed-by: David Howells <dhowells@redhat.com>
Cc: Graff Yang <graff.yang@gmail.com>
Cc: Sonic Zhang <sonic.adi@gmail.com>
Reorganize alloc/free_pcpu_chunk() such that chunk struct alloc/free
live in pcpu_alloc/free_chunk() and the rest in
pcpu_create/destroy_chunk(). While at it, add missing error handling
for chunk->map allocation failure.
This is to allow alternate chunk management implementation for percpu
nommu support.
Signed-off-by: Tejun Heo <tj@kernel.org>
Reviewed-by: David Howells <dhowells@redhat.com>
Cc: Graff Yang <graff.yang@gmail.com>
Cc: Sonic Zhang <sonic.adi@gmail.com>
Factor out pcpu_addr_in_first/reserved_chunk() from
pcpu_chunk_addr_search() and use it to update per_cpu_ptr_to_phys()
such that it handles first chunk differently from the rest.
This patch doesn't cause any functional change and is to prepare for
percpu nommu support.
Signed-off-by: Tejun Heo <tj@kernel.org>
Reviewed-by: David Howells <dhowells@redhat.com>
Cc: Graff Yang <graff.yang@gmail.com>
Cc: Sonic Zhang <sonic.adi@gmail.com>
lockdep has custom code to check whether a pointer belongs to static
percpu area which is somewhat broken. Implement proper
is_kernel/module_percpu_address() and replace the custom code.
On UP, percpu variables are regular static variables and can't be
distinguished from them. Always return %false on UP.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Ingo Molnar <mingo@redhat.com>
Add __percpu sparse annotations to core subsystems.
These annotations are to make sparse consider percpu variables to be
in a different address space and warn if accessed without going
through percpu accessors. This patch doesn't affect normal builds.
Signed-off-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Christoph Lameter <cl@linux-foundation.org>
Acked-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: linux-mm@kvack.org
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Dipankar Sarma <dipankar@in.ibm.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Eric Biederman <ebiederm@xmission.com>
__pcpu_ptr_to_addr() can be overridden by the architecture and might not
behave well if passed a NULL pointer. So avoid calling it until we have
verified that its arg is not NULL.
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Kamalesh Babulal <kamalesh@linux.vnet.ibm.com>
Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Using break statement at the end of a for loop is confusing,
refactor it by replacing the for loop.
Signed-off-by: WANG Cong <amwang@redhat.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
o kdump functionality reserves a per cpu area at boot time and exports the
physical address of that area to user space through sys interface. This
area stores some dump related information like cpu register states etc
at the time of crash.
o We were assuming that per cpu area always come from linearly mapped meory
region and using __pa() to determine physical address.
With percpu_alloc=page, per cpu area can come from vmalloc region also and
__pa() breaks.
o This patch implments a new function to convert per cpu address to
physical address.
Before the patch, crash_notes addresses looked as follows.
cpu0 60fffff49800
cpu1 60fffff60800
cpu2 60fffff77800
These are bogus phsyical addresses.
After the patch, address are following.
cpu0 13eb44000
cpu1 13eb43000
cpu2 13eb42000
cpu3 13eb41000
These look fine. I got 4G of memory and /proc/iomem tell me following.
100000000-13fffffff : System RAM
tj: * added missing asm/io.h include reported by Stephen Rothwell
* repositioned per_cpu_ptr_phys() in percpu.c and added comment.
Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
pcpu_extend_area_map() had the following two bugs.
* It should return 1 if pcpu_lock was dropped and reacquired but it
returned 0. This could lead to oops if free_percpu() races with
area map extension.
* pcpu_mem_free() was called under pcpu_lock. pcpu_mem_free() might
end up calling vfree() which isn't IRQ safe. This could lead to
deadlock through lock order inversion via IRQ.
In addition, Linus pointed out that the temporary lock dropping and
subtle three-way return value of pcpu_extend_area_map() was very ugly
and suggested to split the function into two - pcpu_need_to_extend()
and pcpu_extend_area_map().
This patch restructures pcpu_extend_area_map() as suggested and fixes
the two bugs.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Ingo Molnar <mingo@elte.hu>
Make the following changes to remove some sparse warnings.
* Make DEFINE_PER_CPU_SECTION() declare __pcpu_unique_* before
defining it.
* Annotate pcpu_extend_area_map() that it is entered with pcpu_lock
held, releases it and then reacquires it.
* Make percpu related macros use unique nested variable names.
* While at it, add pcpu prefix to __size_call[_return]() macros as
to-be-implemented sparse annotations will add percpu specific stuff
to these macros.
Signed-off-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Christoph Lameter <cl@linux-foundation.org>
Cc: Rusty Russell <rusty@rustcorp.com.au>
pcpu_alloc() and pcpu_extend_area_map() perform a series of
spin_lock_irq()/spin_unlock_irq() calls, which make them unsafe
with respect to being called from contexts which have IRQs off.
This patch converts the code to perform save/restore of flags instead,
making pcpu_alloc() (or __alloc_percpu() respectively) to be called
from early kernel startup stage, where IRQs are off.
This is needed for proper initialization of per-cpu rq_weight data from
sched_init().
tj: added comment explaining why irqsave/restore is used in alloc path.
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
Acked-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Tejun Heo <tj@kernel.org>
Fix the following two compile warnings which show up on i386.
mm/percpu.c:1873: warning: comparison of distinct pointer types lacks a cast
mm/percpu.c:1879: warning: format '%lx' expects type 'long unsigned int', but argument 2 has type 'size_t'
Signed-off-by: Tejun Heo <tj@kernel.org>
Reported-by: Randy Dunlap <randy.dunlap@oracle.com>
With ia64 converted, there's no arch left which still uses legacy
percpu allocator. Kill it.
Signed-off-by: Tejun Heo <tj@kernel.org>
Delightedly-acked-by: Rusty Russell <rusty@rustcorp.com.au>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Christoph Lameter <cl@linux-foundation.org>
Warn and dump stack when percpu allocation fails. percpu allocator is
still young and unchecked NULL percpu pointer usage can result in
random memory corruption when combined with the pointer shifting in
access macros. Allocation failures should be rare and the warning
message will be disabled after certain times.
Signed-off-by: Tejun Heo <tj@kernel.org>
The parameters to pcpu_setup_first_chunk() come from different sources
depending on architecture and can be quite complex. The function runs
various sanity checks on the parameters and triggers BUG() if
something isn't right. However, this is very early during the boot
and not reporting exactly what the problem is makes debugging even
harder.
Add PCPU_SETUP_BUG() macro which prints out enough information about
the parameters. As the macro still puts separate BUG() for each
check, it won't lose any information even on the situations where only
the program counter can be retrieved.
While at it, also bump pcpu_dump_alloc_info() message to KERN_INFO so
that it's visible on the console if boot fails to complete.
Signed-off-by: Tejun Heo <tj@kernel.org>
Embedding first chunk allocator maintains the distances between units
in the vmalloc area and thus needs vmalloc space to be larger than the
maximum distances between units; otherwise, it wouldn't be able to
create any dynamic chunks. This patch makes the embedding first chunk
allocator check vmalloc space size and if the maximum distance between
units is larger than 75% of it, print warning and, if page mapping
allocator is available, fail initialization so that the system falls
back onto it.
This should work around percpu allocation failure problems on certain
sparc64 configurations where distances between NUMA nodes are larger
than the vmalloc area and makes percpu allocator more robust for
future configurations.
Signed-off-by: Tejun Heo <tj@kernel.org>
pcpu_build_alloc_info() may be called multiple times when percpu is
falling back to different first chunk allocator. Make it clear static
buffers so that they don't contain values from previous runs.
Signed-off-by: Tejun Heo <tj@kernel.org>
pcpu_setup_first_chunk() incorrectly used NR_CPUS as the impossible
unit number while unit number can equal and go over NR_CPUS with
sparse unit map. This triggers BUG_ON() spuriously on machines which
have non-power-of-two number of cpus. Use UINT_MAX instead.
Signed-off-by: Tejun Heo <tj@kernel.org>
Reported-and-tested-by: Tony Vroon <tony@linx.net>
percpu incorrectly assumed that cpu0 was always there which led to the
following warning and eventual oops on sparc machines w/o cpu0.
WARNING: at mm/percpu.c:651 pcpu_map+0xdc/0x100()
Modules linked in:
Call Trace:
[000000000045eb70] warn_slowpath_common+0x50/0xa0
[000000000045ebdc] warn_slowpath_null+0x1c/0x40
[00000000004d493c] pcpu_map+0xdc/0x100
[00000000004d59a4] pcpu_alloc+0x3e4/0x4e0
[00000000004d5af8] __alloc_percpu+0x18/0x40
[00000000005b112c] __percpu_counter_init+0x4c/0xc0
...
Unable to handle kernel NULL pointer dereference
...
I7: <sysfs_new_dirent+0x30/0x120>
Disabling lock debugging due to kernel taint
Caller[000000000053c1b0]: sysfs_new_dirent+0x30/0x120
Caller[000000000053c7a4]: create_dir+0x24/0xc0
Caller[000000000053c870]: sysfs_create_dir+0x30/0x80
Caller[00000000005990e8]: kobject_add_internal+0xc8/0x200
...
Kernel panic - not syncing: Attempted to kill the idle task!
This patch fixes the problem by backporting parts from devel branch to
make percpu core not depend on the existence of cpu0.
Signed-off-by: Tejun Heo <tj@kernel.org>
Reported-by: Meelis Roos <mroos@linux.ee>
Cc: David Miller <davem@davemloft.net>
With x86 converted to embedding allocator, lpage doesn't have any user
left. Kill it along with cpa handling code.
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Jan Beulich <JBeulich@novell.com>
Now that percpu core can handle very sparse units, given that vmalloc
space is large enough, embedding first chunk allocator can use any
memory to build the first chunk. This patch teaches
pcpu_embed_first_chunk() about distances between cpus and to use
alloc/free callbacks to allocate node specific areas for each group
and use them for the first chunk.
This brings the benefits of embedding allocator to NUMA configurations
- no extra TLB pressure with the flexibility of unified dynamic
allocator and no need to restructure arch code to build memory layout
suitable for percpu. With units put into atom_size aligned groups
according to cpu distances, using large page for dynamic chunks is
also easily possible with falling back to reuglar pages if large
allocation fails.
Embedding allocator users are converted to specify NULL
cpu_distance_fn, so this patch doesn't cause any visible behavior
difference. Following patches will convert them.
Signed-off-by: Tejun Heo <tj@kernel.org>
ai->groups[] contains which units need to be put consecutively and at
what offset from the chunk base address. Compile this information
into pcpu_group_offsets[] and pcpu_group_sizes[] in
pcpu_setup_first_chunk() and use them to allocate sparse vm areas
using pcpu_get_vm_areas().
This will be used to allow directly using sparse NUMA memories as
percpu areas.
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Nick Piggin <npiggin@suse.de>
The only thing percpu allocator wants to know about a vmalloc area is
the base address. Instead of requiring chunk->vm, add
chunk->base_addr which contains the necessary value. This simplifies
the code a bit and makes the dummy first_vm unnecessary. This change
will ease allowing a chunk to be mapped by multiple vms.
Signed-off-by: Tejun Heo <tj@kernel.org>
Currently units are mapped sequentially into address space. This
patch adds pcpu_unit_offsets[] which allows units to be mapped to
arbitrary offsets from the chunk base address. This is necessary to
allow sparse embedding which might would need to allocate address
ranges and memory areas which aren't aligned to unit size but
allocation atom size (page or large page size). This also simplifies
things a bit by removing the need to calculate offset from unit
number.
With this change, there's no need for the arch code to know
pcpu_unit_size. Update pcpu_setup_first_chunk() and first chunk
allocators to return regular 0 or -errno return code instead of unit
size or -errno.
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: David S. Miller <davem@davemloft.net>
Till now, non-linear cpu->unit map was expressed using an integer
array which maps each cpu to a unit and used only by lpage allocator.
Although how many units have been placed in a single contiguos area
(group) is known while building unit_map, the information is lost when
the result is recorded into the unit_map array. For lpage allocator,
as all allocations are done by lpages and whether two adjacent lpages
are in the same group or not is irrelevant, this didn't cause any
problem. Non-linear cpu->unit mapping will be used for sparse
embedding and this grouping information is necessary for that.
This patch introduces pcpu_alloc_info which contains all the
information necessary for initializing percpu allocator.
pcpu_alloc_info contains array of pcpu_group_info which describes how
units are grouped and mapped to cpus. pcpu_group_info also has
base_offset field to specify its offset from the chunk's base address.
pcpu_build_alloc_info() initializes this field as if all groups are
allocated back-to-back as is currently done but this will be used to
sparsely place groups.
pcpu_alloc_info is a rather complex data structure which contains a
flexible array which in turn points to nested cpu_map arrays.
* pcpu_alloc_alloc_info() and pcpu_free_alloc_info() are provided to
help dealing with pcpu_alloc_info.
* pcpu_lpage_build_unit_map() is updated to build pcpu_alloc_info,
generalized and renamed to pcpu_build_alloc_info().
@cpu_distance_fn may be NULL indicating that all cpus are of
LOCAL_DISTANCE.
* pcpul_lpage_dump_cfg() is updated to process pcpu_alloc_info,
generalized and renamed to pcpu_dump_alloc_info(). It now also
prints which group each alloc unit belongs to.
* pcpu_setup_first_chunk() now takes pcpu_alloc_info instead of the
separate parameters. All first chunk allocators are updated to use
pcpu_build_alloc_info() to build alloc_info and call
pcpu_setup_first_chunk() with it. This has the side effect of
packing units for sparse possible cpus. ie. if cpus 0, 2 and 4 are
possible, they'll be assigned unit 0, 1 and 2 instead of 0, 2 and 4.
* x86 setup_pcpu_lpage() is updated to deal with alloc_info.
* sparc64 setup_per_cpu_areas() is updated to build alloc_info.
Although the changes made by this patch are pretty pervasive, it
doesn't cause any behavior difference other than packing of sparse
cpus. It mostly changes how information is passed among
initialization functions and makes room for more flexibility.
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: David Miller <davem@davemloft.net>
Daniel Borkmann