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")
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>
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>
Masahiro Yamada
Linus Torvalds
zijun_hu
Tejun Heo
Joe Perches
Tetsuo Handa
Alexander Kuleshov
Baoquan He
Larry Finger
Yannick Guerrini
Dan Carpenter
Guenter Roeck