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percpu: acquire pcpu_lock when updating pcpu_nr_empty_pop_pages 

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+
This commit is contained in:
Tahsin Erdogan 2017-02-25 13:00:19 -08:00 committed by Tejun Heo
parent c1ae3cfa0e
commit 320661b08d
1 changed files with 4 additions and 1 deletions
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5
mm/percpu.c
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@ -1011,8 +1011,11 @@ static void __percpu *pcpu_alloc(size_t size, size_t align, bool reserved,
mutex_unlock(&pcpu_alloc_mutex);
}
if (chunk != pcpu_reserved_chunk)
if (chunk != pcpu_reserved_chunk) {
spin_lock_irqsave(&pcpu_lock, flags);
pcpu_nr_empty_pop_pages -= occ_pages;
spin_unlock_irqrestore(&pcpu_lock, flags);
}
if (pcpu_nr_empty_pop_pages < PCPU_EMPTY_POP_PAGES_LOW)
pcpu_schedule_balance_work();