On Fri, 23 Apr 2010 14:10:32 +0800
Li Zefan <lizf@xxxxxxxxxxxxxx> wrote:
> > From: KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx>
> >
> > css_id() should be called under rcu_read_lock().
> > Following is a report from Li Zefan.
> > ==
> > ===================================================
> > [ INFO: suspicious rcu_dereference_check() usage. ]
> > ---------------------------------------------------
> > kernel/cgroup.c:4438 invoked rcu_dereference_check() without protection!
> >
> > other info that might help us debug this:
> >
> >
> > rcu_scheduler_active = 1, debug_locks = 1
> > 1 lock held by kswapd0/31:
> > #0: (swap_lock){+.+.-.}, at: [<c05058bb>] swap_info_get+0x4b/0xd0
> >
> > stack backtrace:
> ...
> >
> > And css_is_ancestor() should be called under rcu_read_lock().
> >
> >
> > Reported-by: Li Zefan <lizf@xxxxxxxxxxxxxx>
> > Cc: Daisuke Nishimura <nishimura@xxxxxxxxxxxxxxxxx>
> > Cc: Balbir Singh <balbir@xxxxxxxxxxxxxxxxxx>
> > Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx>
>
> With this patch applied, I did some more test, and no warning was triggered.
>
> Tested-by: Li Zefan <lizf@xxxxxxxxxxxxxx>
>
Thank you!.
-Kame
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