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.
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