linux-stable.git/mm/percpu.c, branch v3.18.76

percpu: acquire pcpu_lock when updating pcpu_nr_empty_pop_pages

2017-04-22T05:15:03+00:00

commit 320661b08dd6f1746d5c7ab4eb435ec64b97cd45 upstream.

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: b539b87fed37 ("percpu: implmeent pcpu_nr_empty_pop_pages and chunk->nr_populated")
Signed-off-by: Tahsin Erdogan 
Signed-off-by: Tejun Heo 
Signed-off-by: Greg Kroah-Hartman

percpu: fix synchronization between synchronous map extension and chunk destruction

2016-07-11T14:20:46+00:00

[ Upstream commit 6710e594f71ccaad8101bc64321152af7cd9ea28 ]

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 
Reported-and-tested-by: Alexei Starovoitov 
Reported-by: Vlastimil Babka 
Reported-by: Sasha Levin 
Cc: stable@vger.kernel.org # v3.18+
Fixes: 1a4d76076cda ("percpu: implement asynchronous chunk population")
Signed-off-by: Sasha Levin

percpu: fix synchronization between chunk->map_extend_work and chunk destruction

2016-07-11T14:20:39+00:00

[ Upstream commit 4f996e234dad488e5d9ba0858bc1bae12eff82c3 ]

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 
Reported-and-tested-by: Alexei Starovoitov 
Reported-by: Vlastimil Babka 
Reported-by: Sasha Levin 
Cc: stable@vger.kernel.org # v3.18+
Fixes: 9c824b6a172c ("percpu: make sure chunk->map array has available space")
Signed-off-by: Sasha Levin

mm: kmemleak_alloc_percpu() should follow the gfp from per_alloc()

2015-07-05T14:12:51+00:00

[ Upstream commit 8a8c35fadfaf55629a37ef1a8ead1b8fb32581d2 ]

Beginning at commit d52d3997f843 ("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: [] rtnetlink_rcv+0x1f/0x40
   #1:  (rcu_read_lock_bh){......}, at: [] ipv6_add_addr+0x62/0x540
   #2:  (addrconf_hash_lock){+...+.}, at: [] 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 
Reviewed-by: Kamalesh Babulal 
Acked-by: Martin KaFai Lau 
Signed-off-by: Larry Finger 
Cc: Martin KaFai Lau 
Cc: Catalin Marinas 
Cc: Tejun Heo 
Cc: Christoph Lameter 
Cc: 	[3.18+]
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds 
Signed-off-by: Sasha Levin

percpu: fix how @gfp is interpreted by the percpu allocator

2014-10-08T16:01:52+00:00

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

Revert "percpu: free percpu allocation info for uniprocessor system"

2014-09-22T03:32:38+00:00

This reverts commit 3189eddbcafc ("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 
Cc: Honggang Li 
Signed-off-by: Guenter Roeck 
Signed-off-by: Tejun Heo 
Fixes: 3189eddbcafc ("percpu: free percpu allocation info for uniprocessor system")
Cc: stable@vger.kernel.org # Please don't apply 3189eddbcafc

percpu: fix locking regression in the failure path of pcpu_alloc()

2014-09-08T23:02:45+00:00

While updating locking, b38d08f3181c ("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 
Reported-by: Julia Lawall

percpu: implement asynchronous chunk population

2014-09-02T18:46:05+00:00

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

percpu: rename pcpu_reclaim_work to pcpu_balance_work

2014-09-02T18:46:05+00:00

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

percpu: implmeent pcpu_nr_empty_pop_pages and chunk->nr_populated

2014-09-02T18:46:05+00:00

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