From: Chris Down Date: Sun, 22 Mar 2020 01:22:20 +0000 (-0700) Subject: mm, memcg: fix corruption on 64-bit divisor in memory.high throttling X-Git-Url: http://git.lede-project.org./?a=commitdiff_plain;h=d397a45fc741c80c32a14e2de008441e9976f50c;p=openwrt%2Fstaging%2Fblogic.git 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 Signed-off-by: Chris Down Signed-off-by: Andrew Morton Acked-by: Johannes Weiner Cc: Tejun Heo Cc: Roman Gushchin Cc: Michal Hocko Cc: Nathan Chancellor Cc: [5.4.x+] Link: http://lkml.kernel.org/r/80780887060514967d414b3cd91f9a316a16ab98.1584036142.git.chris@chrisdown.name Signed-off-by: Linus Torvalds --- 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)