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authorChris Down <chris@chrisdown.name>2020-03-21 18:22:20 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2020-03-21 18:56:06 -0700
commitd397a45fc741c80c32a14e2de008441e9976f50c (patch)
tree8cfe10ae8aa3e16783822ad867e1d5b8b615228a
parentd72520ad004a8ce18a6ba6cde317f0081b27365a (diff)
mm, memcg: fix corruption on 64-bit divisor in memory.high throttling
Commit 0e4b01df8659 had a bunch of fixups to use the right division method. However, it seems that after all that it still wasn't right -- div_u64 takes a 32-bit divisor. The headroom is still large (2^32 pages), so on mundane systems you won't hit this, but this should definitely be fixed. Fixes: 0e4b01df8659 ("mm, memcg: throttle allocators when failing reclaim over memory.high") Reported-by: Johannes Weiner <hannes@cmpxchg.org> Signed-off-by: Chris Down <chris@chrisdown.name> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Cc: Tejun Heo <tj@kernel.org> Cc: Roman Gushchin <guro@fb.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: Nathan Chancellor <natechancellor@gmail.com> Cc: <stable@vger.kernel.org> [5.4.x+] Link: http://lkml.kernel.org/r/80780887060514967d414b3cd91f9a316a16ab98.1584036142.git.chris@chrisdown.name Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-rw-r--r--mm/memcontrol.c2
1 files changed, 1 insertions, 1 deletions
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 50492aa9d61b..6d276e1a3321 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -2339,7 +2339,7 @@ void mem_cgroup_handle_over_high(void)
*/
clamped_high = max(high, 1UL);
- overage = div_u64((u64)(usage - high) << MEMCG_DELAY_PRECISION_SHIFT,
+ overage = div64_u64((u64)(usage - high) << MEMCG_DELAY_PRECISION_SHIFT,
clamped_high);
penalty_jiffies = ((u64)overage * overage * HZ)