From: Michal Hocko <mhocko@kernel.org>
To: Chris Down <chris@chrisdown.name>
Cc: Andrew Morton <akpm@linux-foundation.org>,
Johannes Weiner <hannes@cmpxchg.org>, Tejun Heo <tj@kernel.org>,
Roman Gushchin <guro@fb.com>,
linux-mm@kvack.org, cgroups@vger.kernel.org,
linux-kernel@vger.kernel.org, kernel-team@fb.com
Subject: Re: [PATCH 4/6] mm, memcg: Prevent memory.min load/store tearing
Date: Mon, 16 Mar 2020 15:58:25 +0100 [thread overview]
Message-ID: <20200316145825.GP11482@dhcp22.suse.cz> (raw)
In-Reply-To: <e809b4e6b0c1626dac6945970de06409a180ee65.1584034301.git.chris@chrisdown.name>
On Thu 12-03-20 17:33:07, Chris Down wrote:
> This can be set concurrently with reads, which may cause the wrong value
> to be propagated.
>
> Signed-off-by: Chris Down <chris@chrisdown.name>
> Cc: Andrew Morton <akpm@linux-foundation.org>
> Cc: Johannes Weiner <hannes@cmpxchg.org>
> Cc: Roman Gushchin <guro@fb.com>
> Cc: Tejun Heo <tj@kernel.org>
> Cc: linux-mm@kvack.org
> Cc: cgroups@vger.kernel.org
> Cc: linux-kernel@vger.kernel.org
> Cc: kernel-team@fb.com
Acked-by: Michal Hocko <mhocko@suse.com>
> ---
> mm/memcontrol.c | 4 ++--
> mm/page_counter.c | 10 ++++++----
> 2 files changed, 8 insertions(+), 6 deletions(-)
>
> diff --git a/mm/memcontrol.c b/mm/memcontrol.c
> index c85a304fa4a1..e0ed790a2a8c 100644
> --- a/mm/memcontrol.c
> +++ b/mm/memcontrol.c
> @@ -6261,7 +6261,7 @@ enum mem_cgroup_protection mem_cgroup_protected(struct mem_cgroup *root,
> if (!usage)
> return MEMCG_PROT_NONE;
>
> - emin = memcg->memory.min;
> + emin = READ_ONCE(memcg->memory.min);
> elow = READ_ONCE(memcg->memory.low);
>
> parent = parent_mem_cgroup(memcg);
> @@ -6277,7 +6277,7 @@ enum mem_cgroup_protection mem_cgroup_protected(struct mem_cgroup *root,
> if (emin && parent_emin) {
> unsigned long min_usage, siblings_min_usage;
>
> - min_usage = min(usage, memcg->memory.min);
> + min_usage = min(usage, READ_ONCE(memcg->memory.min));
> siblings_min_usage = atomic_long_read(
> &parent->memory.children_min_usage);
>
> diff --git a/mm/page_counter.c b/mm/page_counter.c
> index 18b7f779f2e2..ae471c7d255f 100644
> --- a/mm/page_counter.c
> +++ b/mm/page_counter.c
> @@ -17,14 +17,16 @@ static void propagate_protected_usage(struct page_counter *c,
> 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)) {
> - if (usage <= c->min)
> + min = READ_ONCE(c->min);
> +
> + if (min || atomic_long_read(&c->min_usage)) {
> + if (usage <= min)
> protected = usage;
> else
> protected = 0;
> @@ -217,7 +219,7 @@ void page_counter_set_min(struct page_counter *counter, unsigned long nr_pages)
> {
> 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));
> --
> 2.25.1
>
--
Michal Hocko
SUSE Labs
next prev parent reply other threads:[~2020-03-16 14:58 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-03-12 17:32 [PATCH 0/6] mm, memcg: cgroup v2 tunable load/store tearing fixes Chris Down
2020-03-12 17:32 ` [PATCH 1/6] mm, memcg: Prevent memory.high load/store tearing Chris Down
2020-03-16 14:54 ` Michal Hocko
2020-03-12 17:32 ` [PATCH 2/6] mm, memcg: Prevent memory.max load tearing Chris Down
2020-03-16 14:56 ` Michal Hocko
2020-03-12 17:33 ` [PATCH 3/6] mm, memcg: Prevent memory.low load/store tearing Chris Down
2020-03-16 14:57 ` Michal Hocko
2020-06-12 17:03 ` Michal Koutný
2020-06-12 17:13 ` Chris Down
2020-03-12 17:33 ` [PATCH 4/6] mm, memcg: Prevent memory.min " Chris Down
2020-03-16 14:58 ` Michal Hocko [this message]
2020-03-12 17:33 ` [PATCH 5/6] mm, memcg: Prevent memory.swap.max load tearing Chris Down
2020-03-16 14:58 ` Michal Hocko
2020-03-12 17:33 ` [PATCH 6/6] mm, memcg: Prevent mem_cgroup_protected store tearing Chris Down
2020-03-16 14:59 ` Michal Hocko
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