Messages in this thread | | | Date | Tue, 28 Nov 2017 21:00:05 +0100 | From | Michal Hocko <> | Subject | Re: [PATCH] mm, memcg: fix mem_cgroup_swapout() for THPs |
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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
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