Messages in this thread | | | Date | Tue, 26 Apr 2016 15:57:52 +0200 | From | Michal Hocko <> | Subject | Re: [PATCH] oom: consider multi-threaded tasks in task_will_free_mem |
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On Tue 12-04-16 11:19:16, Michal Hocko wrote: > From: Michal Hocko <mhocko@suse.com> > > task_will_free_mem is a misnomer for a more complex PF_EXITING test > for early break out from the oom killer because it is believed that > such a task would release its memory shortly and so we do not have > to select an oom victim and perform a disruptive action. > > Currently we make sure that the given task is not participating in the > core dumping because it might get blocked for a long time - see > d003f371b270 ("oom: don't assume that a coredumping thread will exit > soon"). > > The check can still do better though. We shouldn't consider the task > unless the whole thread group is going down. This is rather unlikely > but not impossible. A single exiting thread would surely leave all the > address space behind. If we are really unlucky it might get stuck on the > exit path and keep its TIF_MEMDIE and so block the oom killer. > > Signed-off-by: Michal Hocko <mhocko@suse.com> > --- > > Hi, > I hope I got it right but I would really appreciate if Oleg found some > time and double checked after me. The fix is more cosmetic than anything > else but I guess it is worth it.
ping...
> > Thanks! > > include/linux/oom.h | 15 +++++++++++++-- > 1 file changed, 13 insertions(+), 2 deletions(-) > > diff --git a/include/linux/oom.h b/include/linux/oom.h > index 628a43242a34..b09c7dc523ff 100644 > --- a/include/linux/oom.h > +++ b/include/linux/oom.h > @@ -102,13 +102,24 @@ extern struct task_struct *find_lock_task_mm(struct task_struct *p); > > static inline bool task_will_free_mem(struct task_struct *task) > { > + struct signal_struct *sig = task->signal; > + > /* > * A coredumping process may sleep for an extended period in exit_mm(), > * so the oom killer cannot assume that the process will promptly exit > * and release memory. > */ > - return (task->flags & PF_EXITING) && > - !(task->signal->flags & SIGNAL_GROUP_COREDUMP); > + if (sig->flags & SIGNAL_GROUP_COREDUMP) > + return false; > + > + if (!(task->flags & PF_EXITING)) > + return false; > + > + /* Make sure that the whole thread group is going down */ > + if (!thread_group_empty(task) && !(sig->flags & SIGNAL_GROUP_EXIT)) > + return false; > + > + return true; > } > > /* sysctls */ > -- > 2.8.0.rc3 >
-- Michal Hocko SUSE Labs
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