Messages in this thread | | | Date | Wed, 2 Jun 2010 22:38:27 +0200 | From | Oleg Nesterov <> | Subject | Re: [PATCH] oom: Make coredump interruptible |
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On 06/02, Roland McGrath wrote: > > > when select_bad_process() finds the task P to kill it can participate > > in the core dump (sleep in exit_mm), but we should somehow inform the > > thread which actually dumps the core: P->mm->core_state->dumper. > > Perhaps it should simply do that: if you would choose P to oom-kill, and > P->mm->core_state!=NULL, then choose P->mm->core_state->dumper instead.
... to set TIF_MEMDIE which should be checked in elf_core_dump().
Probably yes.
> > Well, we can use TIF_MEMDIE if we chose the right thread, I think. > > But perhaps mm->flags |= MMF_OOM is better, it can have other user. > > I dunno. > > This is all the quick hack before get around to just making core dumping > fully-interruptible, no? So we should go with whatever is the simplest > change now.
Yes.
> Perhaps this belongs in another thread as you suggested. But I wonder what > we might get just from s/TASK_UNINTERRUPTIBLE/TASK_KILLABLE/ in exit_mm.
Oh. This needs more thinking. Definitely the task sleeping in exit_mm() must not exit until core_state->dumper->thread returns from do_coredump(). If nothing else, the dumper can use its task_struct and it relies on the stable core_thread->next list. And right now TASK_KILLABLE can't work anyway, it is possible that fatal_signal_pending() is true.
But perhaps we can do something later. Assuming that do_coredump() is interruptible, TASK_KILLABLE can make the difference only if the dumper belongs to another thread-group.
Oleg.
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