Messages in this thread Patch in this message | | | From | Waiman Long <> | Subject | [PATCH] mm/memcontrol: Don't increase effective low/min if no protection needed | Date | Tue, 11 Oct 2022 10:30:15 -0400 |
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Since commit bc50bcc6e00b ("mm: memcontrol: clean up and document effective low/min calculations"), the effective low/min protections can be non-zero even if the corresponding memory.low/min values are 0. That can surprise users to see MEMCG_LOW events even when the memory.low value is not set. One example is the LTP's memcontrol04 test which fails because it detects some MEMCG_LOW events for a cgroup with a memory.min value of 0.
Fix this by updating effective_protection() to not returning a non-zero low/min protection values if the corresponding memory.low/min values or those of its parent are 0.
Fixes: bc50bcc6e00b ("mm: memcontrol: clean up and document effective low/min calculations") Signed-off-by: Waiman Long <longman@redhat.com> --- mm/memcontrol.c | 3 +++ 1 file changed, 3 insertions(+)
diff --git a/mm/memcontrol.c b/mm/memcontrol.c index b69979c9ced5..893d4d5e518a 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -6660,6 +6660,9 @@ static unsigned long effective_protection(unsigned long usage, unsigned long protected; unsigned long ep; + if (!setting || !parent_effective) + return 0UL; /* No protection is needed */ + protected = min(usage, setting); /* * If all cgroups at this level combined claim and use more -- 2.31.1
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