From 854e24294fc7d1a08d7a27a0f0859017313a3e4c Mon Sep 17 00:00:00 2001 From: Cong Wang Date: Tue, 21 Oct 2014 09:27:12 +0200 Subject: [PATCH] freezer: Do not freeze tasks killed by OOM killer Since e4fa9b9abef298 (oom: thaw threads if oom killed thread is frozen before deferring) OOM killer relies on being able to thaw a frozen task to handle OOM situation but 9a01316a9184 (freezer: make freezing() test freeze conditions in effect instead of TIF_FREEZE) has reorganized the code and stopped clearing freeze flag in __thaw_task. This means that the target task only wakes up and goes into the fridge again because the freezing condition hasn't changed for it. This reintroduces the bug fixed by e4fa9b9abef298. Fix the issue by checking for TIF_MEMDIE thread flag in freezing_slow_path and exclude the task from freezing completely. If a task was already frozen it would get woken by __thaw_task from OOM killer and get out of freezer after rechecking freezing(). Changes since v1 - put TIF_MEMDIE check into freezing_slowpath rather than in __refrigerator as per Oleg - return __thaw_task into oom_scan_process_thread because oom_kill_process will not wake task in the fridge because it is sleeping uninterruptible [mhocko@suse.cz: rewrote the changelog] Fixes: 9a01316a9184 (freezer: make freezing() test freeze conditions in effect instead of TIF_FREEZE) Cc: 3.3+ # 3.3+ Signed-off-by: Cong Wang Signed-off-by: Michal Hocko Acked-by: Oleg Nesterov Signed-off-by: Rafael J. Wysocki --- kernel/freezer.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/kernel/freezer.c b/kernel/freezer.c index aa6a8aadb911f..8f9279b9c6d7d 100644 --- a/kernel/freezer.c +++ b/kernel/freezer.c @@ -42,6 +42,9 @@ bool freezing_slow_path(struct task_struct *p) if (p->flags & (PF_NOFREEZE | PF_SUSPEND_TASK)) return false; + if (test_thread_flag(TIF_MEMDIE)) + return false; + if (pm_nosig_freezing || cgroup_freezing(p)) return true; -- 2.39.5