The patch titled
Subject: kasan: resched in quarantine_remove_cache()
has been added to the -mm tree. Its filename is
kasan-resched-in-quarantine_remove_cache.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/kasan-resched-in-quarantine_remove_cache.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/kasan-resched-in-quarantine_remove_cache.patch
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------------------------------------------------------
From: Dmitry Vyukov <dvyukov@xxxxxxxxxx>
Subject: kasan: resched in quarantine_remove_cache()
We see reported stalls/lockups in quarantine_remove_cache() on machines
with large amounts of RAM. quarantine_remove_cache() needs to scan whole
quarantine in order to take out all objects belonging to the cache.
Quarantine is currently 1/32-th of RAM, e.g. on a machine with 256GB of
memory that will be 8GB. Moreover quarantine scanning is a walk over
uncached linked list, which is slow.
Add cond_resched() after scanning of each non-empty batch of objects.
Batches are specifically kept of reasonable size for quarantine_put(). On
a machine with 256GB of RAM we should have ~512 non-empty batches, each
with 16MB of objects.
Link: http://lkml.kernel.org/r/20170308154239.25440-1-dvyukov@xxxxxxxxxx
Signed-off-by: Dmitry Vyukov <dvyukov@xxxxxxxxxx>
Cc: Andrey Ryabinin <aryabinin@xxxxxxxxxxxxx>
Cc: Greg Thelen <gthelen@xxxxxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/kasan/quarantine.c | 9 ++++++++-
1 file changed, 8 insertions(+), 1 deletion(-)
diff -puN mm/kasan/quarantine.c~kasan-resched-in-quarantine_remove_cache mm/kasan/quarantine.c
--- a/mm/kasan/quarantine.c~kasan-resched-in-quarantine_remove_cache
+++ a/mm/kasan/quarantine.c
@@ -283,8 +283,15 @@ void quarantine_remove_cache(struct kmem
on_each_cpu(per_cpu_remove_cache, cache, 1);
spin_lock_irqsave(&quarantine_lock, flags);
- for (i = 0; i < QUARANTINE_BATCHES; i++)
+ for (i = 0; i < QUARANTINE_BATCHES; i++) {
+ if (qlist_empty(&global_quarantine[i]))
+ continue;
qlist_move_cache(&global_quarantine[i], &to_free, cache);
+ /* Scanning whole quarantine can take a while. */
+ spin_unlock_irqrestore(&quarantine_lock, flags);
+ cond_resched();
+ spin_lock_irqsave(&quarantine_lock, flags);
+ }
spin_unlock_irqrestore(&quarantine_lock, flags);
qlist_free_all(&to_free, cache);
_
Patches currently in -mm which might be from dvyukov@xxxxxxxxxx are
kasan-resched-in-quarantine_remove_cache.patch
kasan-fix-races-in-quarantine_remove_cache.patch