* Re: [PATCH] mm, memcg: fix mem_cgroup_swapout() for THPs
2017-11-28 16:19 [PATCH] mm, memcg: fix mem_cgroup_swapout() for THPs Shakeel Butt
@ 2017-11-28 20:00 ` Michal Hocko
2017-11-28 20:09 ` Shakeel Butt
2017-11-29 0:38 ` Huang, Ying
2017-11-29 10:17 ` Johannes Weiner
2 siblings, 1 reply; 5+ messages in thread
From: Michal Hocko @ 2017-11-28 20:00 UTC (permalink / raw)
To: Shakeel Butt
Cc: Huang Ying, Vladimir Davydov, Greg Thelen, Johannes Weiner,
Andrew Morton, linux-mm, linux-kernel, cgroups, stable
On Tue 28-11-17 08:19:41, Shakeel Butt wrote:
> The commit d6810d730022 ("memcg, THP, swap: make mem_cgroup_swapout()
> support THP") changed mem_cgroup_swapout() to support transparent huge
> page (THP). However the patch missed one location which should be
> changed for correctly handling THPs. The resulting bug will cause the
> memory cgroups whose THPs were swapped out to become zombies on
> deletion.
Very well spotted! Have you seen this triggering or you found it by the
code inspection?
> Fixes: d6810d730022 ("memcg, THP, swap: make mem_cgroup_swapout() support THP")
To be honest I am not really happy how the whole THP swapout thing has
been rushed in without a proper review. I am partly guildy for not find
time for the proper review but this is not something that really had to
be merged without a single ack or reviewed-by.
> Signed-off-by: Shakeel Butt <shakeelb@google.com>
> Cc: stable@vger.kernel.org
Acked-by: Michal Hocko <mhocko@suse.com>
Thanks!
> ---
> mm/memcontrol.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/mm/memcontrol.c b/mm/memcontrol.c
> index 50e6906314f8..ac2ffd5e02b9 100644
> --- a/mm/memcontrol.c
> +++ b/mm/memcontrol.c
> @@ -6044,7 +6044,7 @@ void mem_cgroup_swapout(struct page *page, swp_entry_t entry)
> memcg_check_events(memcg, page);
>
> if (!mem_cgroup_is_root(memcg))
> - css_put(&memcg->css);
> + css_put_many(&memcg->css, nr_entries);
> }
>
> /**
> --
> 2.15.0.417.g466bffb3ac-goog
--
Michal Hocko
SUSE Labs
--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org. For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>
^ permalink raw reply [flat|nested] 5+ messages in thread* Re: [PATCH] mm, memcg: fix mem_cgroup_swapout() for THPs
2017-11-28 20:00 ` Michal Hocko
@ 2017-11-28 20:09 ` Shakeel Butt
0 siblings, 0 replies; 5+ messages in thread
From: Shakeel Butt @ 2017-11-28 20:09 UTC (permalink / raw)
To: Michal Hocko
Cc: Huang Ying, Vladimir Davydov, Greg Thelen, Johannes Weiner,
Andrew Morton, Linux MM, LKML, Cgroups, stable
On Tue, Nov 28, 2017 at 12:00 PM, Michal Hocko <mhocko@kernel.org> wrote:
> On Tue 28-11-17 08:19:41, Shakeel Butt wrote:
>> The commit d6810d730022 ("memcg, THP, swap: make mem_cgroup_swapout()
>> support THP") changed mem_cgroup_swapout() to support transparent huge
>> page (THP). However the patch missed one location which should be
>> changed for correctly handling THPs. The resulting bug will cause the
>> memory cgroups whose THPs were swapped out to become zombies on
>> deletion.
>
> Very well spotted! Have you seen this triggering or you found it by the
> code inspection?
>
By code inspection.
--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org. For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH] mm, memcg: fix mem_cgroup_swapout() for THPs
2017-11-28 16:19 [PATCH] mm, memcg: fix mem_cgroup_swapout() for THPs Shakeel Butt
2017-11-28 20:00 ` Michal Hocko
@ 2017-11-29 0:38 ` Huang, Ying
2017-11-29 10:17 ` Johannes Weiner
2 siblings, 0 replies; 5+ messages in thread
From: Huang, Ying @ 2017-11-29 0:38 UTC (permalink / raw)
To: Shakeel Butt
Cc: Huang Ying, Vladimir Davydov, Michal Hocko, Greg Thelen,
Johannes Weiner, Andrew Morton, linux-mm, linux-kernel, cgroups,
stable
Shakeel Butt <shakeelb@google.com> writes:
> The commit d6810d730022 ("memcg, THP, swap: make mem_cgroup_swapout()
> support THP") changed mem_cgroup_swapout() to support transparent huge
> page (THP). However the patch missed one location which should be
> changed for correctly handling THPs. The resulting bug will cause the
> memory cgroups whose THPs were swapped out to become zombies on
> deletion.
Good catch! Thanks a lot for fixing!
Best Regards,
Huang, Ying
> Fixes: d6810d730022 ("memcg, THP, swap: make mem_cgroup_swapout() support THP")
> Signed-off-by: Shakeel Butt <shakeelb@google.com>
> Cc: stable@vger.kernel.org
> ---
> mm/memcontrol.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/mm/memcontrol.c b/mm/memcontrol.c
> index 50e6906314f8..ac2ffd5e02b9 100644
> --- a/mm/memcontrol.c
> +++ b/mm/memcontrol.c
> @@ -6044,7 +6044,7 @@ void mem_cgroup_swapout(struct page *page, swp_entry_t entry)
> memcg_check_events(memcg, page);
>
> if (!mem_cgroup_is_root(memcg))
> - css_put(&memcg->css);
> + css_put_many(&memcg->css, nr_entries);
> }
>
> /**
--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org. For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>
^ permalink raw reply [flat|nested] 5+ messages in thread* Re: [PATCH] mm, memcg: fix mem_cgroup_swapout() for THPs
2017-11-28 16:19 [PATCH] mm, memcg: fix mem_cgroup_swapout() for THPs Shakeel Butt
2017-11-28 20:00 ` Michal Hocko
2017-11-29 0:38 ` Huang, Ying
@ 2017-11-29 10:17 ` Johannes Weiner
2 siblings, 0 replies; 5+ messages in thread
From: Johannes Weiner @ 2017-11-29 10:17 UTC (permalink / raw)
To: Shakeel Butt
Cc: Huang Ying, Vladimir Davydov, Michal Hocko, Greg Thelen,
Andrew Morton, linux-mm, linux-kernel, cgroups, stable
On Tue, Nov 28, 2017 at 08:19:41AM -0800, Shakeel Butt wrote:
> The commit d6810d730022 ("memcg, THP, swap: make mem_cgroup_swapout()
> support THP") changed mem_cgroup_swapout() to support transparent huge
> page (THP). However the patch missed one location which should be
> changed for correctly handling THPs. The resulting bug will cause the
> memory cgroups whose THPs were swapped out to become zombies on
> deletion.
>
> Fixes: d6810d730022 ("memcg, THP, swap: make mem_cgroup_swapout() support THP")
> Signed-off-by: Shakeel Butt <shakeelb@google.com>
> Cc: stable@vger.kernel.org
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org. For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>
^ permalink raw reply [flat|nested] 5+ messages in thread