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Date: Thu, 23 Nov 2017 14:46:29 +0100 From: Michal Hocko <mhocko@...nel.org> To: Tetsuo Handa <penguin-kernel@...ove.SAKURA.ne.jp> Cc: jack@...e.cz, viro@...iv.linux.org.uk, david@...morbit.com, linux-kernel@...r.kernel.org, linux-fsdevel@...r.kernel.org, akpm@...ux-foundation.org Subject: Re: [PATCH] fs: handle shrinker registration failure in sget_userns On Thu 23-11-17 22:35:34, Tetsuo Handa wrote: > Jan Kara wrote: > > Looks good to me now. You can add: > > > > Reviewed-by: Jan Kara <jack@...e.cz> > > > > It does not look good to me, for "goto fail" can call > destroy_unused_super() before s->s_shrink.list is initialized. > Also, the comment block saying "this object isn't exposed yet" > wants to be updated? > > --- > fs/super.c | 10 +++------- > 1 file changed, 3 insertions(+), 7 deletions(-) > > diff --git a/fs/super.c b/fs/super.c > index 80b118c..44f0c6b 100644 > --- a/fs/super.c > +++ b/fs/super.c > @@ -197,6 +197,7 @@ static struct super_block *alloc_super(struct file_system_type *type, int flags, > if (!s) > return NULL; > > + INIT_LIST_HEAD(&s->s_shrink.list); > INIT_LIST_HEAD(&s->s_mounts); > s->s_user_ns = get_user_ns(user_ns); > You are right. I will move it. > @@ -260,9 +261,8 @@ static struct super_block *alloc_super(struct file_system_type *type, int flags, > s->s_shrink.count_objects = super_cache_count; > s->s_shrink.batch = 1024; > s->s_shrink.flags = SHRINKER_NUMA_AWARE | SHRINKER_MEMCG_AWARE; > - INIT_LIST_HEAD(&s->s_shrink.list); > - return s; > - > + if (register_shrinker(&s->s_shrink) == 0) > + return s; > fail: > destroy_unused_super(s); > return NULL; But I am not sure this is correct. So what protects shrinker invocation while the object is not initialized yet? -- Michal Hocko SUSE Labs
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