* [PATCH 2/3] percpu: acquire pcpu_lock when updating pcpu_nr_empty_pop_pages
@ 2017-02-25 21:00 Tahsin Erdogan
2017-03-06 20:56 ` Tejun Heo
0 siblings, 1 reply; 2+ messages in thread
From: Tahsin Erdogan @ 2017-02-25 21:00 UTC (permalink / raw)
To: Tejun Heo, Christoph Lameter, Andrew Morton, Chris Wilson,
Andrey Ryabinin, Roman Pen, Joonas Lahtinen, Michal Hocko,
zijun_hu, Joonsoo Kim
Cc: linux-mm, linux-kernel, Tahsin Erdogan
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 <tahsin@google.com>
---
mm/percpu.c | 5 ++++-
1 file changed, 4 insertions(+), 1 deletion(-)
diff --git a/mm/percpu.c b/mm/percpu.c
index 0686f566d347..232356a2d914 100644
--- a/mm/percpu.c
+++ b/mm/percpu.c
@@ -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();
--
2.11.0.483.g087da7b7c-goog
^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [PATCH 2/3] percpu: acquire pcpu_lock when updating pcpu_nr_empty_pop_pages
2017-02-25 21:00 [PATCH 2/3] percpu: acquire pcpu_lock when updating pcpu_nr_empty_pop_pages Tahsin Erdogan
@ 2017-03-06 20:56 ` Tejun Heo
0 siblings, 0 replies; 2+ messages in thread
From: Tejun Heo @ 2017-03-06 20:56 UTC (permalink / raw)
To: Tahsin Erdogan
Cc: Christoph Lameter, Andrew Morton, Chris Wilson, Andrey Ryabinin,
Roman Pen, Joonas Lahtinen, Michal Hocko, zijun_hu, Joonsoo Kim,
linux-mm, linux-kernel
On Sat, Feb 25, 2017 at 01:00:19PM -0800, Tahsin Erdogan wrote:
> 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 <tahsin@google.com>
Applied to percpu/for-4.11-fixes w/ stable cc'd.
Thanks.
--
tejun
^ permalink raw reply [flat|nested] 2+ messages in thread
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