Patch "percpu: acquire pcpu_lock when updating pcpu_nr_empty_pop_pages" has been added to the 4.10-stable tree

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 <[email protected]> know about it.

From: Tahsin Erdogan <[email protected]>
Date: Sat, 25 Feb 2017 13:00:19 -0800
Subject: percpu: acquire pcpu_lock when updating pcpu_nr_empty_pop_pages

From: Tahsin Erdogan <[email protected]>

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.

---
 mm/percpu.c |    5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

@@ -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 [email protected] are

queue-4.10/percpu-acquire-pcpu_lock-when-updating-pcpu_nr_empty_pop_pages.patch