Re: [BUG] memcg: panic when rmdir()

[Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp>]

On Fri, 16 Jan 2009 17:26:51 +0900, Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp> wrote:
> On Fri, 16 Jan 2009 17:07:24 +0900, KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> wrote:
> > From: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
> > 
> > Now, at swapoff, even while try_charge() fails, commit is executed.
> > This is bug and make refcnt of cgroup_subsys_state minus, finally.
> > 
> Nice catch!
> 
> I think this bug can explain this problem I've seen.
> Commiting on trycharge failure will add the pc to the lru
> without a corresponding charge and refcnt.
> And rmdir uncharges the pc(so we get WARNING: at kernel/res_counter.c:71)
> and decrements the refcnt(so we get BUG at kernel/cgroup.c:2517).
> 
> Even if the problem cannot be fixed by this patch, this patch is valid and needed.
> 
> > Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
> Reviewed-by: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp>
> 
> I'll test it.
> 
I've tested several times, but this problem didn't happen.

Tested-by: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp>


Thanks,
Daisuke Nishimura.

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