2018-04-06 05:08:45

by Stephen Rothwell

[permalink] [raw]

Subject: linux-next: build warning after merge of the akpm-current tree

---

Hi Andrew,

After merging the akpm-current tree, today's linux-next build (x86_64
allmodconfig) produced this warning:

mm/memcontrol.c: In function 'memory_events_show':
mm/memcontrol.c:5453:23: warning: array subscript is above array bounds [-Warray-bounds]
atomic_long_read(&memcg->memory_events[OOM_KILL]));
^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Introduced by commit

725844c87a0d ("mm: memcg: make sure memory.events is uptodate when waking pollers")

--
Cheers,
Stephen Rothwell

---

Attachments:

(No filename) (499.00 B)
OpenPGP digital signature

2018-04-06 15:54:43

by Johannes Weiner

[permalink] [raw]

Subject: [patch] mm: memcg: make sure memory.events is uptodate when waking pollers fix

---

On Fri, Apr 06, 2018 at 02:53:30PM +1000, Stephen Rothwell wrote:
> Hi Andrew,
>
> After merging the akpm-current tree, today's linux-next build (x86_64
> allmodconfig) produced this warning:
>
> mm/memcontrol.c: In function 'memory_events_show':
> mm/memcontrol.c:5453:23: warning: array subscript is above array bounds [-Warray-bounds]
> atomic_long_read(&memcg->memory_events[OOM_KILL]));
> ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>
> Introduced by commit
>
> 725844c87a0d ("mm: memcg: make sure memory.events is uptodate when waking pollers")

Ah, silly, I missed that warning. The below fixes it.

Signed-off-by: Johannes Weiner <[email protected]>
---

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 04ea2b104ee2..9bac6dc26e09 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -5199,8 +5199,7 @@ static int memory_events_show(struct seq_file *m, void *v)
atomic_long_read(&memcg->memory_events[MEMCG_MAX]));
seq_printf(m, "oom %lu\n",
atomic_long_read(&memcg->memory_events[MEMCG_OOM]));
- seq_printf(m, "oom_kill %lu\n",
- atomic_long_read(&memcg->memory_events[OOM_KILL]));
+ seq_printf(m, "oom_kill %lu\n", memcg_sum_events(memcg, OOM_KILL));

return 0;
}

2018-04-06 16:13:10

by Michal Hocko

[permalink] [raw]

Subject: Re: [patch] mm: memcg: make sure memory.events is uptodate when waking pollers fix

---

On Fri 06-04-18 11:54:41, Johannes Weiner wrote:
> On Fri, Apr 06, 2018 at 02:53:30PM +1000, Stephen Rothwell wrote:
> > Hi Andrew,
> >
> > After merging the akpm-current tree, today's linux-next build (x86_64
> > allmodconfig) produced this warning:
> >
> > mm/memcontrol.c: In function 'memory_events_show':
> > mm/memcontrol.c:5453:23: warning: array subscript is above array bounds [-Warray-bounds]
> > atomic_long_read(&memcg->memory_events[OOM_KILL]));
> > ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> >
> > Introduced by commit
> >
> > 725844c87a0d ("mm: memcg: make sure memory.events is uptodate when waking pollers")
>
> Ah, silly, I missed that warning. The below fixes it.
>
> Signed-off-by: Johannes Weiner <[email protected]>
> ---
>
> diff --git a/mm/memcontrol.c b/mm/memcontrol.c
> index 04ea2b104ee2..9bac6dc26e09 100644
> --- a/mm/memcontrol.c
> +++ b/mm/memcontrol.c
> @@ -5199,8 +5199,7 @@ static int memory_events_show(struct seq_file *m, void *v)
> atomic_long_read(&memcg->memory_events[MEMCG_MAX]));
> seq_printf(m, "oom %lu\n",
> atomic_long_read(&memcg->memory_events[MEMCG_OOM]));
> - seq_printf(m, "oom_kill %lu\n",
> - atomic_long_read(&memcg->memory_events[OOM_KILL]));
> + seq_printf(m, "oom_kill %lu\n", memcg_sum_events(memcg, OOM_KILL));

Ohh, this is so easy to miss.

--
Michal Hocko
SUSE Labs