From: Michal Hocko Date: Fri, 20 May 2016 23:57:24 +0000 (-0700) Subject: oom: consider multi-threaded tasks in task_will_free_mem X-Git-Url: https://git.stricted.de/?a=commitdiff_plain;h=98748bd72200;p=GitHub%2Fmoto-9609%2Fandroid_kernel_motorola_exynos9610.git oom: consider multi-threaded tasks in task_will_free_mem task_will_free_mem is a misnomer for a more complex PF_EXITING test for early break out from the oom killer because it is believed that such a task would release its memory shortly and so we do not have to select an oom victim and perform a disruptive action. Currently we make sure that the given task is not participating in the core dumping because it might get blocked for a long time - see commit d003f371b270 ("oom: don't assume that a coredumping thread will exit soon"). The check can still do better though. We shouldn't consider the task unless the whole thread group is going down. This is rather unlikely but not impossible. A single exiting thread would surely leave all the address space behind. If we are really unlucky it might get stuck on the exit path and keep its TIF_MEMDIE and so block the oom killer. Link: http://lkml.kernel.org/r/1460452756-15491-1-git-send-email-mhocko@kernel.org Signed-off-by: Michal Hocko Cc: Oleg Nesterov Cc: David Rientjes Cc: Tetsuo Handa Cc: Joonsoo Kim Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- diff --git a/include/linux/oom.h b/include/linux/oom.h index 83b9c39bd8b7..d3f533f2f481 100644 --- a/include/linux/oom.h +++ b/include/linux/oom.h @@ -110,13 +110,24 @@ extern struct task_struct *find_lock_task_mm(struct task_struct *p); static inline bool task_will_free_mem(struct task_struct *task) { + struct signal_struct *sig = task->signal; + /* * A coredumping process may sleep for an extended period in exit_mm(), * so the oom killer cannot assume that the process will promptly exit * and release memory. */ - return (task->flags & PF_EXITING) && - !(task->signal->flags & SIGNAL_GROUP_COREDUMP); + if (sig->flags & SIGNAL_GROUP_COREDUMP) + return false; + + if (!(task->flags & PF_EXITING)) + return false; + + /* Make sure that the whole thread group is going down */ + if (!thread_group_empty(task) && !(sig->flags & SIGNAL_GROUP_EXIT)) + return false; + + return true; } /* sysctls */