The patch titled
Subject: mm, memcg: fix corruption on 64-bit divisor in memory.high throttling
has been added to the -mm tree. Its filename is
mm-memcg-fix-corruption-on-64-bit-divisor-in-memoryhigh-throttling.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/mm-memcg-fix-corruption-on-64-bit-divisor-in-memoryhigh-throttling.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/mm-memcg-fix-corruption-on-64-bit-divisor-in-memoryhigh-throttling.patch
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------------------------------------------------------
From: Chris Down <chris@xxxxxxxxxxxxxx>
Subject: mm, memcg: fix corruption on 64-bit divisor in memory.high throttling
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.
Link: http://lkml.kernel.org/r/80780887060514967d414b3cd91f9a316a16ab98.1584036142.git.chris@xxxxxxxxxxxxxx
Fixes: 0e4b01df8659 ("mm, memcg: throttle allocators when failing reclaim over memory.high")
Signed-off-by: Chris Down <chris@xxxxxxxxxxxxxx>
Reported-by: Johannes Weiner <hannes@xxxxxxxxxxx>
Cc: Tejun Heo <tj@xxxxxxxxxx>
Cc: Roman Gushchin <guro@xxxxxx>
Cc: Michal Hocko <mhocko@xxxxxxxxxx>
Cc: Nathan Chancellor <natechancellor@xxxxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx> [5.4.x+]
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/memcontrol.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
--- a/mm/memcontrol.c~mm-memcg-fix-corruption-on-64-bit-divisor-in-memoryhigh-throttling
+++ a/mm/memcontrol.c
@@ -2350,7 +2350,7 @@ 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)
_
Patches currently in -mm which might be from chris@xxxxxxxxxxxxxx are
mm-memcg-fix-corruption-on-64-bit-divisor-in-memoryhigh-throttling.patch
mm-memcg-throttle-allocators-based-on-ancestral-memoryhigh.patch
