On Mon 01-06-15 21:10:18, Tetsuo Handa wrote:
> Michal Hocko wrote:
> > On Mon 01-06-15 19:51:05, Tetsuo Handa wrote:
> > [...]
> > > How can all fatal_signal_pending() "struct task_struct" get access to memory
> > > reserves when only one of fatal_signal_pending() "struct task_struct" has
> > > TIF_MEMDIE ?
> >
> > Because of
> > /*
> > * If current has a pending SIGKILL or is exiting, then automatically
> > * select it. The goal is to allow it to allocate so that it may
> > * quickly exit and free its memory.
> > *
> > * But don't select if current has already released its mm and cleared
> > * TIF_MEMDIE flag at exit_mm(), otherwise an OOM livelock may occur.
> > */
> > if (current->mm &&
> > (fatal_signal_pending(current) || task_will_free_mem(current))) {
> > mark_oom_victim(current);
> > goto out;
> > }
>
> Then, what guarantees that the thread which is between
> down_write(¤t->mm->mmap_sem) and up_write(¤t->mm->mmap_sem)
> (or whatever locks which are blocking the OOM victim) calls out_of_memory() ?
> That thread might be doing !__GFP_FS allocation request.
Could you point to such a place?
--
Michal Hocko
SUSE Labs
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