On 09/20, Tetsuo Handa wrote: > > Oleg Nesterov wrote: > > On 09/17, Kyle Walker wrote: > > > > > > Currently, the oom killer will attempt to kill a process that is in > > > TASK_UNINTERRUPTIBLE state. For tasks in this state for an exceptional > > > period of time, such as processes writing to a frozen filesystem during > > > a lengthy backup operation, this can result in a deadlock condition as > > > related processes memory access will stall within the page fault > > > handler. > > > > And there are other potential reasons for deadlock. > > > > Stupid idea. Can't we help the memory hog to free its memory? This is > > orthogonal to other improvements we can do. > > So, we are trying to release memory without waiting for arriving at > exit_mm() from do_exit(), right? If it works, it will be a simple and > small change that will be easy to backport. > > The idea is that since fatal_signal_pending() tasks no longer return to > user space, we can release memory allocated for use by user space, right? Yes. > Then, I think that this approach can be applied to not only OOM-kill case > but also regular kill(pid, SIGKILL) case (i.e. kick from signal_wake_up(1) > or somewhere?). I don't think so... but we might want to do this if (say) we are not going to kill someone else because fatal_signal_pending(current). > A dedicated kernel thread (not limited to OOM-kill purpose) > scans for fatal_signal_pending() tasks and release that task's memory. Perhaps a dedicated kernel thread makes sense (see other emails), but I don't think it should scan the killed threads. oom-kill should kict it. Anyway, let me repeat there are a lot of details we might want to discuss. But the initial changes should be simple as possible, imo. Oleg. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>