forked from luck/tmp_suning_uos_patched
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 <mhocko@suse.com> Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Cc: Oleg Nesterov <oleg@redhat.com> Cc: David Rientjes <rientjes@google.com> Cc: Vladimir Davydov <vdavydov@parallels.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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@ -58,6 +58,11 @@ static inline bool oom_task_origin(const struct task_struct *p)
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return p->signal->oom_flag_origin;
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}
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static inline bool tsk_is_oom_victim(struct task_struct * tsk)
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{
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return tsk->signal->oom_mm;
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}
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extern unsigned long oom_badness(struct task_struct *p,
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struct mem_cgroup *memcg, const nodemask_t *nodemask,
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unsigned long totalpages);
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@ -524,7 +524,7 @@ static inline int get_dumpable(struct mm_struct *mm)
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#define MMF_HAS_UPROBES 19 /* has uprobes */
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#define MMF_RECALC_UPROBES 20 /* MMF_HAS_UPROBES can be wrong */
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#define MMF_OOM_REAPED 21 /* mm has been already reaped */
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#define MMF_OOM_SKIP 21 /* mm is of no interest for the OOM killer */
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#define MMF_INIT_MASK (MMF_DUMPABLE_MASK | MMF_DUMP_FILTER_MASK)
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@ -672,7 +672,6 @@ struct signal_struct {
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atomic_t sigcnt;
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atomic_t live;
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int nr_threads;
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atomic_t oom_victims; /* # of TIF_MEDIE threads in this thread group */
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struct list_head thread_head;
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wait_queue_head_t wait_chldexit; /* for wait4() */
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@ -862,6 +862,7 @@ static inline void __mmput(struct mm_struct *mm)
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}
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if (mm->binfmt)
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module_put(mm->binfmt->module);
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set_bit(MMF_OOM_SKIP, &mm->flags);
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mmdrop(mm);
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}
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@ -186,7 +186,7 @@ unsigned long oom_badness(struct task_struct *p, struct mem_cgroup *memcg,
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*/
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adj = (long)p->signal->oom_score_adj;
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if (adj == OOM_SCORE_ADJ_MIN ||
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test_bit(MMF_OOM_REAPED, &p->mm->flags) ||
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test_bit(MMF_OOM_SKIP, &p->mm->flags) ||
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in_vfork(p)) {
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task_unlock(p);
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return 0;
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@ -296,11 +296,11 @@ static int oom_evaluate_task(struct task_struct *task, void *arg)
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/*
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* This task already has access to memory reserves and is being killed.
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* Don't allow any other task to have access to the reserves unless
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* the task has MMF_OOM_REAPED because chances that it would release
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* the task has MMF_OOM_SKIP because chances that it would release
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* any memory is quite low.
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*/
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if (!is_sysrq_oom(oc) && atomic_read(&task->signal->oom_victims)) {
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if (test_bit(MMF_OOM_REAPED, &task->signal->oom_mm->flags))
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if (!is_sysrq_oom(oc) && tsk_is_oom_victim(task)) {
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if (test_bit(MMF_OOM_SKIP, &task->signal->oom_mm->flags))
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goto next;
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goto abort;
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}
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@ -572,7 +572,7 @@ static void oom_reap_task(struct task_struct *tsk)
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* Hide this mm from OOM killer because it has been either reaped or
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* somebody can't call up_write(mmap_sem).
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*/
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set_bit(MMF_OOM_REAPED, &mm->flags);
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set_bit(MMF_OOM_SKIP, &mm->flags);
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/* Drop a reference taken by wake_oom_reaper */
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put_task_struct(tsk);
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@ -654,8 +654,6 @@ static void mark_oom_victim(struct task_struct *tsk)
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if (test_and_set_tsk_thread_flag(tsk, TIF_MEMDIE))
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return;
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atomic_inc(&tsk->signal->oom_victims);
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/* oom_mm is bound to the signal struct life time. */
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if (!cmpxchg(&tsk->signal->oom_mm, NULL, mm))
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atomic_inc(&tsk->signal->oom_mm->mm_count);
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@ -677,7 +675,6 @@ void exit_oom_victim(struct task_struct *tsk)
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{
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if (!test_and_clear_tsk_thread_flag(tsk, TIF_MEMDIE))
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return;
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atomic_dec(&tsk->signal->oom_victims);
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if (!atomic_dec_return(&oom_victims))
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wake_up_all(&oom_victims_wait);
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@ -769,7 +766,7 @@ static bool task_will_free_mem(struct task_struct *task)
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* This task has already been drained by the oom reaper so there are
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* only small chances it will free some more
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*/
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if (test_bit(MMF_OOM_REAPED, &mm->flags))
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if (test_bit(MMF_OOM_SKIP, &mm->flags))
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return false;
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if (atomic_read(&mm->mm_users) <= 1)
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@ -906,7 +903,7 @@ static void oom_kill_process(struct oom_control *oc, const char *message)
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* killer to guarantee OOM forward progress.
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*/
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can_oom_reap = false;
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set_bit(MMF_OOM_REAPED, &mm->flags);
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set_bit(MMF_OOM_SKIP, &mm->flags);
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pr_info("oom killer %d (%s) has mm pinned by %d (%s)\n",
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task_pid_nr(victim), victim->comm,
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task_pid_nr(p), p->comm);
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