On Mon, 7 Mar 2011, Andrew Vagin wrote: > > Andrey is patching the case where an eligible TIF_MEMDIE process is found > > but it has already detached its ->mm. In combination with the patch > > posted to linux-mm, oom: prevent unnecessary oom kills or kernel panics, > > which makes select_bad_process() iterate over all threads, it is an > > effective solution. > > Probably you said about the first version of my patch. > This version is incorrect because of > http://git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=dd8e8f405ca386c7ce7cbb996ccd985d283b0e03 > > but my first patch is correct and it has a simple reproducer(I > attached it). You can execute it and your kernel hangs up, because the > parent doesn't wait children, but the one child (zombie) will have > flag TIF_MEMDIE, oom_killer will kill nobody > The second version of your patch works fine in combination with the pending "oom: prevent unnecessary oom kills or kernel panics" patch from linux-mm (included below). Try your test case with both this patch and the second version of your patch. diff --git a/mm/oom_kill.c b/mm/oom_kill.c --- a/mm/oom_kill.c +++ b/mm/oom_kill.c @@ -292,11 +292,11 @@ static struct task_struct *select_bad_process(unsigned int *ppoints, unsigned long totalpages, struct mem_cgroup *mem, const nodemask_t *nodemask) { - struct task_struct *p; + struct task_struct *g, *p; struct task_struct *chosen = NULL; *ppoints = 0; - for_each_process(p) { + do_each_thread(g, p) { unsigned int points; if (oom_unkillable_task(p, mem, nodemask)) @@ -324,7 +324,7 @@ static struct task_struct *select_bad_process(unsigned int *ppoints, * the process of exiting and releasing its resources. * Otherwise we could get an easy OOM deadlock. */ - if (thread_group_empty(p) && (p->flags & PF_EXITING) && p->mm) { + if ((p->flags & PF_EXITING) && p->mm) { if (p != current) return ERR_PTR(-1UL); @@ -337,7 +337,7 @@ static struct task_struct *select_bad_process(unsigned int *ppoints, chosen = p; *ppoints = points; } - } + } while_each_thread(g, p); return chosen; }