In the berserker mode we kill a bunch of tasks that are as bad as the selected victim. We assume two tasks to be equally bad if they consume the same permille of memory. With such a strict check, it might turn out that oom berserker won't kill any tasks in case a fork bomb is running inside a container while the effect of killing a task eating <=1/1000th of memory won't be enough to cope with memory shortage. Let's loosen this check and use percentage instead of permille. In this case, it might still happen that berserker won't kill anyone, but in this case the regular oom should free at least 1/100th of memory, which should be enough even for small containers.
Also, check berserker mode even if the victim has already exited by the time we are about to send SIGKILL to it. Rationale: when the berserker is in rage, it might kill hundreds of tasks so that the next oom kill is likely to select an exiting task. Not triggering berserker in this case will result in oom stalls. Signed-off-by: Vladimir Davydov <[email protected]> --- mm/oom_kill.c | 16 +++++++--------- 1 file changed, 7 insertions(+), 9 deletions(-) diff --git a/mm/oom_kill.c b/mm/oom_kill.c index 5bc4ccfcf41f..2d0fcac6f52b 100644 --- a/mm/oom_kill.c +++ b/mm/oom_kill.c @@ -757,11 +757,11 @@ static void oom_berserker(unsigned long points, unsigned long overdraft, continue; /* - * Consider tasks as equally bad if they have equal - * normalized scores. + * Consider tasks as equally bad if they occupy equal + * percentage of available memory. */ - if (tsk_points * 1000 / totalpages < - points * 1000 / totalpages) + if (tsk_points * 100 / totalpages < + points * 100 / totalpages) continue; if (__ratelimit(&berserker_rs)) { @@ -809,8 +809,7 @@ void oom_kill_process(struct task_struct *p, gfp_t gfp_mask, int order, if (p->mm && p->flags & PF_EXITING) { mark_oom_victim(p); task_unlock(p); - put_task_struct(p); - return; + goto out; } task_unlock(p); @@ -855,8 +854,7 @@ void oom_kill_process(struct task_struct *p, gfp_t gfp_mask, int order, p = find_lock_task_mm(victim); if (!p) { - put_task_struct(victim); - return; + goto out; } else if (victim != p) { get_task_struct(p); put_task_struct(victim); @@ -902,8 +900,8 @@ void oom_kill_process(struct task_struct *p, gfp_t gfp_mask, int order, do_send_sig_info(SIGKILL, SEND_SIG_FORCED, victim, true); mem_cgroup_note_oom_kill(memcg, victim); +out: put_task_struct(victim); - oom_berserker(points, overdraft, totalpages, memcg, nodemask); } #undef K -- 2.1.4 _______________________________________________ Devel mailing list [email protected] https://lists.openvz.org/mailman/listinfo/devel
