From 862e3073b3eed13f17bd6be6ca6052db15c0b728 Mon Sep 17 00:00:00 2001 From: Michal Hocko Date: Fri, 7 Oct 2016 16:58:57 -0700 Subject: mm, oom: get rid of signal_struct::oom_victims After "oom: keep mm of the killed task available" we can safely detect an oom victim by checking task->signal->oom_mm so we do not need the signal_struct counter anymore so let's get rid of it. This alone wouldn't be sufficient for nommu archs because exit_oom_victim doesn't hide the process from the oom killer anymore. We can, however, mark the mm with a MMF flag in __mmput. We can reuse MMF_OOM_REAPED and rename it to a more generic MMF_OOM_SKIP. Link: http://lkml.kernel.org/r/1472119394-11342-6-git-send-email-mhocko@kernel.org Signed-off-by: Michal Hocko Cc: Tetsuo Handa Cc: Oleg Nesterov Cc: David Rientjes Cc: Vladimir Davydov Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/oom_kill.c | 17 +++++++---------- 1 file changed, 7 insertions(+), 10 deletions(-) (limited to 'mm/oom_kill.c') diff --git a/mm/oom_kill.c b/mm/oom_kill.c index f16ec0840a0e..e2a2c35dd493 100644 --- a/mm/oom_kill.c +++ b/mm/oom_kill.c @@ -186,7 +186,7 @@ unsigned long oom_badness(struct task_struct *p, struct mem_cgroup *memcg, */ adj = (long)p->signal->oom_score_adj; if (adj == OOM_SCORE_ADJ_MIN || - test_bit(MMF_OOM_REAPED, &p->mm->flags) || + test_bit(MMF_OOM_SKIP, &p->mm->flags) || in_vfork(p)) { task_unlock(p); return 0; @@ -296,11 +296,11 @@ static int oom_evaluate_task(struct task_struct *task, void *arg) /* * This task already has access to memory reserves and is being killed. * Don't allow any other task to have access to the reserves unless - * the task has MMF_OOM_REAPED because chances that it would release + * the task has MMF_OOM_SKIP because chances that it would release * any memory is quite low. */ - if (!is_sysrq_oom(oc) && atomic_read(&task->signal->oom_victims)) { - if (test_bit(MMF_OOM_REAPED, &task->signal->oom_mm->flags)) + if (!is_sysrq_oom(oc) && tsk_is_oom_victim(task)) { + if (test_bit(MMF_OOM_SKIP, &task->signal->oom_mm->flags)) goto next; goto abort; } @@ -572,7 +572,7 @@ done: * Hide this mm from OOM killer because it has been either reaped or * somebody can't call up_write(mmap_sem). */ - set_bit(MMF_OOM_REAPED, &mm->flags); + set_bit(MMF_OOM_SKIP, &mm->flags); /* Drop a reference taken by wake_oom_reaper */ put_task_struct(tsk); @@ -654,8 +654,6 @@ static void mark_oom_victim(struct task_struct *tsk) if (test_and_set_tsk_thread_flag(tsk, TIF_MEMDIE)) return; - atomic_inc(&tsk->signal->oom_victims); - /* oom_mm is bound to the signal struct life time. */ if (!cmpxchg(&tsk->signal->oom_mm, NULL, mm)) atomic_inc(&tsk->signal->oom_mm->mm_count); @@ -677,7 +675,6 @@ void exit_oom_victim(struct task_struct *tsk) { if (!test_and_clear_tsk_thread_flag(tsk, TIF_MEMDIE)) return; - atomic_dec(&tsk->signal->oom_victims); if (!atomic_dec_return(&oom_victims)) wake_up_all(&oom_victims_wait); @@ -769,7 +766,7 @@ static bool task_will_free_mem(struct task_struct *task) * This task has already been drained by the oom reaper so there are * only small chances it will free some more */ - if (test_bit(MMF_OOM_REAPED, &mm->flags)) + if (test_bit(MMF_OOM_SKIP, &mm->flags)) return false; if (atomic_read(&mm->mm_users) <= 1) @@ -906,7 +903,7 @@ static void oom_kill_process(struct oom_control *oc, const char *message) * killer to guarantee OOM forward progress. */ can_oom_reap = false; - set_bit(MMF_OOM_REAPED, &mm->flags); + set_bit(MMF_OOM_SKIP, &mm->flags); pr_info("oom killer %d (%s) has mm pinned by %d (%s)\n", task_pid_nr(victim), victim->comm, task_pid_nr(p), p->comm); -- cgit