Commit 320661b0 authored Feb 25, 2017 by Tahsin Erdogan Committed by Tejun Heo Mar 06, 2017

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: b539b87f ("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+

parent c1ae3cfa

mm/percpu.c

+4 −1

Original line number	Diff line number	Diff line
		@@ -1011,8 +1011,11 @@ area_found:
		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();

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