lkml.org 
[lkml]   [2009]   [Jan]   [14]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    Date
    From
    SubjectRe: [RFC][PATCH 5/4] memcg: don't call res_counter_uncharge when obsolete
    * KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> [2009-01-15 12:24:16]:

    > On Wed, 14 Jan 2009 19:25:39 +0530
    > Balbir Singh <balbir@linux.vnet.ibm.com> wrote:
    >
    > > * Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp> [2009-01-14 17:51:21]:
    > >
    > > > This is a new one. Please review.
    > > >
    > > > ===
    > > > From: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp>
    > > >
    > > > mem_cgroup_get ensures that the memcg that has been got can be accessed
    > > > even after the directory has been removed, but it doesn't ensure that parents
    > > > of it can be accessed: parents might have been freed already by rmdir.
    > > >
    > > > This causes a bug in case of use_hierarchy==1, because res_counter_uncharge
    > > > climb up the tree.
    > > >
    > > > Check if the memcg is obsolete, and don't call res_counter_uncharge when obsole.
    > > >
    > > > Signed-off-by: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp>
    > >
    > > I liked the earlier, EBUSY approach that ensured that parents could
    > > not go away if children exist. IMHO, the code has gotten too complex
    > > and has too many corner cases. Time to revisit it.
    > >
    >
    > But I don't like -EBUSY ;)
    >
    > When rmdir() returns -EBUSY even if there are no (visible) children and tasks,
    > our customer will take kdump and send it to me "please explain this kernel bug"
    >
    > I'm sure it will happen ;)
    >

    OK, but memory.stat can show why the group is busy and with
    move_to_parent() such issues should not occur right? I'll relook at
    the code. Thanks for your input.

    --
    Balbir


    \
     
     \ /
      Last update: 2009-01-15 05:21    [W:0.028 / U:60.644 seconds]
    ©2003-2016 Jasper Spaans. hosted at Digital OceanAdvertise on this site