> From: Oleg Nesterov <oleg@xxxxxxxxxx> > > Almost all ->mm == NUL checks in oom_kill.c are wrong. > > The current code assumes that the task without ->mm has already > released its memory and ignores the process. However this is not > necessarily true when this process is multithreaded, other live > sub-threads can use this ->mm. > > - Remove the "if (!p->mm)" check in select_bad_process(), it is > just wrong. > > - Add the new helper, find_lock_task_mm(), which finds the live > thread which uses the memory and takes task_lock() to pin ->mm > > - change oom_badness() to use this helper instead of just checking > ->mm != NULL. > > - As David pointed out, select_bad_process() must never choose the > task without ->mm, but no matter what oom_badness() returns the > task can be chosen if nothing else has been found yet. > > Change oom_badness() to return int, change it to return -1 if > find_lock_task_mm() fails, and change select_bad_process() to > check points >= 0. > > Note! This patch is not enough, we need more changes. > > - oom_badness() was fixed, but oom_kill_task() still ignores > the task without ->mm > > - oom_forkbomb_penalty() should use find_lock_task_mm() too, > and it also needs other changes to actually find the first > first-descendant children > > This will be addressed later. > > Signed-off-by: Oleg Nesterov <oleg@xxxxxxxxxx> > Signed-off-by: David Rientjes <rientjes@xxxxxxxxxx> need respin. -- 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>