On 09/30, Tetsuo Handa wrote:
>
> Oleg Nesterov wrote:
> > Just in case, this doesn't depend on the previous series I sent.
> >
> > Tetsuo, iirc we already discussed the change in 1/2 some time ago,
> > could you review?
> >
> > Oleg.
>
> I tested patch 1/2 and 2/2 on next-20150929 using reproducer at
> http://lkml.kernel.org/r/201503150240.gii00591.ovsftqlofoh...@i-love.sakura.ne.jp
> .
>
> $ while :; do ./a.out; done
>
> Unfortunately, since hangup on coredump to pipe occurs sometimes,
> I can't tell whether this patchset solves hangup on coredump to pipe.
Obviously it doesn't. There are a lot more problems here.
It is hardly possible to enumerate them, but let me quote the changelog
from d003f371b27016354c
Note: this is only the first step, this patch doesn't try to solve other
problems. The SIGNAL_GROUP_COREDUMP check is obviously racy, a task can
participate in coredump after it was already observed in PF_EXITING state,
so TIF_MEMDIE (which also blocks oom-killer) still can be wrongly set.
fatal_signal_pending() can be true because of SIGNAL_GROUP_COREDUMP so
out_of_memory() and mem_cgroup_out_of_memory() shouldn't blindly trust it.
And even the name/usage of the new helper is confusing, an exiting thread
can only free its ->mm if it is the only/last task in thread group.
This patch just makes the SIGNAL_GROUP_COREDUMP check in task_will_free_mem()
a bit more correct wrt CLONE_VM tasks, nothing more.
Oleg.
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