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    SubjectRe: [PATCH] oom: Make coredump interruptible
    On 06/04, KOSAKI Motohiro wrote:
    >
    > > ... to set TIF_MEMDIE which should be checked in elf_core_dump().
    > >
    > > Probably yes.
    >
    > Yep, probably. but can you please allow me additonal explanation?
    >
    > In multi threaded OOM case, we have two problematic routine, coredump
    > and vmscan. Roland's idea can only solve the former.
    >
    > But I also interest vmscan quickly exit if OOM received.

    Yes, agreed. See another email from me, MMF_ flags looks "obviously
    useful" to me.

    (I'd suggest you to add a note into the changelog, to explain
    that the new flag makes sense even without coredump problems).

    > @@ -410,6 +409,8 @@ static int __oom_kill_process(struct task_struct *p, struct mem_cgroup *mem,
    > */
    > p->rt.time_slice = HZ;
    > set_tsk_thread_flag(p, TIF_MEMDIE);
    > + set_bit(MMF_OOM_KILLED, &p->mm->flags);
    > + task_unlock(p);

    IIUC, it has find_lock_task() mm above and thus we can trust p->mm ?
    (I am asking just in case, I lost the plot a bit).

    Ack or Reviewed, whatever your prefer.

    Very minor nit.

    > @@ -2038,6 +2038,10 @@ static int elf_core_dump(struct coredump_params *cprm)
    > page_cache_release(page);
    > } else
    > stop = !dump_seek(cprm->file, PAGE_SIZE);
    > +
    > + /* The task need to exit ASAP if received OOM. */
    > + if (test_bit(MMF_OOM_KILLED, &current->mm->flags))
    > + stop = 1;

    Perhaps this check makes more sense at the start of the loop,
    and there is no need to set "stop = 1" (this var is not visible
    outside of "for (;;) {}" anyway). Cosmetic, up to you.

    Oleg.



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