Hello.
I see suspicious asymmetry, in the current mainline:
> WRITE_ONCE(memcg->memory.emin, effective_protection(usage, parent_usage,
> READ_ONCE(memcg->memory.min),
> READ_ONCE(parent->memory.emin),
> atomic_long_read(&parent->memory.children_min_usage)));
>
> WRITE_ONCE(memcg->memory.elow, effective_protection(usage, parent_usage,
> memcg->memory.low, READ_ONCE(parent->memory.elow),
> atomic_long_read(&parent->memory.children_low_usage)));
On Thu, Mar 12, 2020 at 05:33:01PM +0000, Chris Down <chris@xxxxxxxxxxxxxx> wrote:
> diff --git a/mm/memcontrol.c b/mm/memcontrol.c
> index aca2964ea494..c85a304fa4a1 100644
> --- a/mm/memcontrol.c
> +++ b/mm/memcontrol.c
> @@ -6262,7 +6262,7 @@ enum mem_cgroup_protection mem_cgroup_protected(struct mem_cgroup *root,
> return MEMCG_PROT_NONE;
>
> emin = memcg->memory.min;
> - elow = memcg->memory.low;
> + elow = READ_ONCE(memcg->memory.low);
>
> parent = parent_mem_cgroup(memcg);
> /* No parent means a non-hierarchical mode on v1 memcg */
> @@ -6291,7 +6291,7 @@ enum mem_cgroup_protection mem_cgroup_protected(struct mem_cgroup *root,
> if (elow && parent_elow) {
> unsigned long low_usage, siblings_low_usage;
>
> - low_usage = min(usage, memcg->memory.low);
> + low_usage = min(usage, READ_ONCE(memcg->memory.low));
> siblings_low_usage = atomic_long_read(
> &parent->memory.children_low_usage);
Is it possible that these hunks were lost during rebase/merge?
IMHO it should apply as:
-- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -6428,7 +6428,8 @@ enum mem_cgroup_protection mem_cgroup_protected(struct mem_cgroup *root,
atomic_long_read(&parent->memory.children_min_usage)));
WRITE_ONCE(memcg->memory.elow, effective_protection(usage, parent_usage,
- memcg->memory.low, READ_ONCE(parent->memory.elow),
+ READ_ONCE(memcg->memory.low),
+ READ_ONCE(parent->memory.elow),
atomic_long_read(&parent->memory.children_low_usage)));
out:
Michal
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