On Fri 03-10-14 11:03:30, Cong Wang wrote: > On Fri, Oct 3, 2014 at 8:13 AM, Michal Hocko <mho...@suse.cz> wrote: > > > > That commit fixes an OOM deadlock. Not a soft lockup. Do you have the > > OOM killer report from the log? This would tell us that the killed task > > was indeed sleeping on the lock which is hold by the charger which > > triggered the OOM. I am little bit surprised that I do not see any OOM > > related functions on the stacks (maybe the code is inlined...). > > > Oh, did you see __mem_cgroup_try_charge() calls > schedule_timeout_uninterruptible() in stack trace? Yes, they are inlined > and I don't see any other possibilities for calling it.
Yes the only place we call schedule_timeout_uninterruptible from is mem_cgroup_handle_oom. And it happens only for a task which hasn't been killed by OOM killer. > > It would be better to know what exactly is going on before backporting > > this change because it is quite large. > > > > I thought the stack trace I showed is obvious. :) I am very happy > to investigate if you see any other path calling > schedule_timeout_uninterruptible() > in __mem_cgroup_try_charge(). I was expecting an oom report which kills a task which is sleeping on a lock which is held on the way up to the charge function. Your report mentioned a task waiting for i_mutex for too long. It is true that the charging path is holding an i_mutex as well so it might be the same situation handled by the said patch. But it is not 100% clear this is the case without an OOM report which would point to the waiting task. The memcg might be trashing on the hard limit and reclaim might take a long time. -- Michal Hocko SUSE Labs -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
