On Sun, Mar 28, 2010 at 06:28:21PM +0200, Oleg Nesterov wrote: > On 03/28, anfei wrote: > > > > On Fri, Mar 26, 2010 at 11:33:56PM +0100, Oleg Nesterov wrote: > > > > > Off-topic, but we shouldn't use force_sig(), SIGKILL doesn't > > > need "force" semantics. > > > > > This may need a dedicated patch, there are some other places to > > force_sig(SIGKILL, ...) too. > > Yes, yes, sure. > > > > I'd wish I could understand the changelog ;) > > > > > Assume thread A and B are in the same group. If A runs into the oom, > > and selects B as the victim, B won't exit because at least in exit_mm(), > > it can not get the mm->mmap_sem semaphore which A has already got. > > I see. But still I can't understand. To me, the problem is not that > B can't exit, the problem is that A doesn't know it should exit. All If B can exit, its memory will be freed, and A will be able to allocate the memory, so A won't loop here. Regards, Anfei. > threads should exit and free ->mm. Even if B could exit, this is not > enough. And, to some extent, it doesn't matter if it holds mmap_sem > or not. > > Don't get me wrong. Even if I don't understand oom_kill.c the patch > looks obviously good to me, even from "common sense" pov. I am just > curious. > > So, my understanding is: we are going to kill the whole thread group > but TIF_MEMDIE is per-thread. Mark the whole thread group as TIF_MEMDIE > so that any thread can notice this flag and (say, __alloc_pages_slowpath) > fail asap. > > Is my understanding correct? > > Oleg. > -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxxx For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>