This is a note to let you know that I've just added the patch titled
percpu: acquire pcpu_lock when updating pcpu_nr_empty_pop_pages
to the 4.10-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
percpu-acquire-pcpu_lock-when-updating-pcpu_nr_empty_pop_pages.patch
and it can be found in the queue-4.10 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 320661b08dd6f1746d5c7ab4eb435ec64b97cd45 Mon Sep 17 00:00:00 2001
From: Tahsin Erdogan <tahsin@xxxxxxxxxx>
Date: Sat, 25 Feb 2017 13:00:19 -0800
Subject: percpu: acquire pcpu_lock when updating pcpu_nr_empty_pop_pages
From: Tahsin Erdogan <tahsin@xxxxxxxxxx>
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 <tahsin@xxxxxxxxxx>
Signed-off-by: Tejun Heo <tj@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
mm/percpu.c | 5 ++++-
1 file changed, 4 insertions(+), 1 deletion(-)
--- a/mm/percpu.c
+++ b/mm/percpu.c
@@ -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();
Patches currently in stable-queue which might be from tahsin@xxxxxxxxxx are
queue-4.10/percpu-acquire-pcpu_lock-when-updating-pcpu_nr_empty_pop_pages.patch