The patch titled
Subject: mm, memcg: prevent memory.min load/store tearing
has been added to the -mm tree. Its filename is
mm-memcg-prevent-memorymin-load-store-tearing.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/mm-memcg-prevent-memorymin-load-store-tearing.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/mm-memcg-prevent-memorymin-load-store-tearing.patch
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------------------------------------------------------
From: Chris Down <chris@xxxxxxxxxxxxxx>
Subject: mm, memcg: prevent memory.min load/store tearing
This can be set concurrently with reads, which may cause the wrong value
to be propagated.
Link: http://lkml.kernel.org/r/e809b4e6b0c1626dac6945970de06409a180ee65.1584034301.git.chris@xxxxxxxxxxxxxx
Signed-off-by: Chris Down <chris@xxxxxxxxxxxxxx>
Cc: Johannes Weiner <hannes@xxxxxxxxxxx>
Cc: Roman Gushchin <guro@xxxxxx>
Cc: Tejun Heo <tj@xxxxxxxxxx>
Cc: Michal Hocko <mhocko@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/memcontrol.c | 5 +++--
mm/page_counter.c | 9 +++++----
2 files changed, 8 insertions(+), 6 deletions(-)
--- a/mm/memcontrol.c~mm-memcg-prevent-memorymin-load-store-tearing
+++ a/mm/memcontrol.c
@@ -6390,7 +6390,7 @@ enum mem_cgroup_protection mem_cgroup_pr
return MEMCG_PROT_NONE;
if (parent == root) {
- memcg->memory.emin = memcg->memory.min;
+ memcg->memory.emin = READ_ONCE(memcg->memory.min);
memcg->memory.elow = memcg->memory.low;
goto out;
}
@@ -6398,7 +6398,8 @@ enum mem_cgroup_protection mem_cgroup_pr
parent_usage = page_counter_read(&parent->memory);
memcg->memory.emin = effective_protection(usage, parent_usage,
- memcg->memory.min, READ_ONCE(parent->memory.emin),
+ READ_ONCE(memcg->memory.min),
+ READ_ONCE(parent->memory.emin),
atomic_long_read(&parent->memory.children_min_usage));
memcg->memory.elow = effective_protection(usage, parent_usage,
--- a/mm/page_counter.c~mm-memcg-prevent-memorymin-load-store-tearing
+++ a/mm/page_counter.c
@@ -17,14 +17,15 @@ static void propagate_protected_usage(st
unsigned long usage)
{
unsigned long protected, old_protected;
- unsigned long low;
+ unsigned long low, min;
long delta;
if (!c->parent)
return;
- if (c->min || atomic_long_read(&c->min_usage)) {
- protected = min(usage, c->min);
+ min = READ_ONCE(c->min);
+ if (min || atomic_long_read(&c->min_usage)) {
+ protected = min(usage, min);
old_protected = atomic_long_xchg(&c->min_usage, protected);
delta = protected - old_protected;
if (delta)
@@ -207,7 +208,7 @@ void page_counter_set_min(struct page_co
{
struct page_counter *c;
- counter->min = nr_pages;
+ WRITE_ONCE(counter->min, nr_pages);
for (c = counter; c; c = c->parent)
propagate_protected_usage(c, atomic_long_read(&c->usage));
_
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
mm-memcg-prevent-memoryhigh-load-store-tearing.patch
mm-memcg-prevent-memorymax-load-tearing.patch
mm-memcg-prevent-memorylow-load-store-tearing.patch
mm-memcg-prevent-memorymin-load-store-tearing.patch
mm-memcg-prevent-memoryswapmax-load-tearing.patch
mm-memcg-prevent-mem_cgroup_protected-store-tearing.patch
