All of lore.kernel.org
 help / color / mirror / Atom feed
From: Michal Hocko <mhocko@kernel.org>
To: linux-mm@kvack.org
Cc: Andrew Morton <akpm@linux-foundation.org>,
	Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>,
	Oleg Nesterov <oleg@redhat.com>,
	David Rientjes <rientjes@google.com>,
	Vladimir Davydov <vdavydov@parallels.com>,
	Michal Hocko <mhocko@suse.com>
Subject: [PATCH v2 5/9] mm, oom: get rid of signal_struct::oom_victims
Date: Thu, 25 Aug 2016 12:03:10 +0200	[thread overview]
Message-ID: <1472119394-11342-6-git-send-email-mhocko@kernel.org> (raw)
In-Reply-To: <1472119394-11342-1-git-send-email-mhocko@kernel.org>

From: Michal Hocko <mhocko@suse.com>

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.

Signed-off-by: Michal Hocko <mhocko@suse.com>
---
 include/linux/oom.h   |  5 +++++
 include/linux/sched.h |  3 +--
 kernel/fork.c         |  1 +
 mm/oom_kill.c         | 17 +++++++----------
 4 files changed, 14 insertions(+), 12 deletions(-)

diff --git a/include/linux/oom.h b/include/linux/oom.h
index 17946e5121b6..b61357d07170 100644
--- a/include/linux/oom.h
+++ b/include/linux/oom.h
@@ -58,6 +58,11 @@ static inline bool oom_task_origin(const struct task_struct *p)
 	return p->signal->oom_flag_origin;
 }
 
+static inline bool tsk_is_oom_victim(struct task_struct * tsk)
+{
+	return tsk->signal->oom_mm;
+}
+
 extern unsigned long oom_badness(struct task_struct *p,
 		struct mem_cgroup *memcg, const nodemask_t *nodemask,
 		unsigned long totalpages);
diff --git a/include/linux/sched.h b/include/linux/sched.h
index cccb575dc242..eda579f3283a 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -521,7 +521,7 @@ static inline int get_dumpable(struct mm_struct *mm)
 
 #define MMF_HAS_UPROBES		19	/* has uprobes */
 #define MMF_RECALC_UPROBES	20	/* MMF_HAS_UPROBES can be wrong */
-#define MMF_OOM_REAPED		21	/* mm has been already reaped */
+#define MMF_OOM_SKIP		21	/* mm is of no interest for the OOM killer */
 
 #define MMF_INIT_MASK		(MMF_DUMPABLE_MASK | MMF_DUMP_FILTER_MASK)
 
@@ -669,7 +669,6 @@ struct signal_struct {
 	atomic_t		sigcnt;
 	atomic_t		live;
 	int			nr_threads;
-	atomic_t oom_victims; /* # of TIF_MEDIE threads in this thread group */
 	struct list_head	thread_head;
 
 	wait_queue_head_t	wait_chldexit;	/* for wait4() */
diff --git a/kernel/fork.c b/kernel/fork.c
index 136a2c6784cb..64624fb42f96 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -725,6 +725,7 @@ static inline void __mmput(struct mm_struct *mm)
 	}
 	if (mm->binfmt)
 		module_put(mm->binfmt->module);
+	set_bit(MMF_OOM_SKIP, &mm->flags);
 	mmdrop(mm);
 }
 
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 @@ static void oom_reap_task(struct task_struct *tsk)
 	 * 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);
-- 
2.8.1

--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org.  For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>

  parent reply	other threads:[~2016-08-25 10:03 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-08-25 10:03 [PATCH v2 0/10] fortify oom killer even more Michal Hocko
2016-08-25 10:03 ` [PATCH v2 1/9] mm,oom_reaper: Reduce find_lock_task_mm() usage Michal Hocko
2016-08-25 10:03 ` [PATCH v2 2/9] mm,oom_reaper: Do not attempt to reap a task twice Michal Hocko
2016-08-25 10:03 ` [PATCH v2 3/9] oom: keep mm of the killed task available Michal Hocko
2016-08-25 10:03 ` [PATCH v2 4/9] kernel, oom: fix potential pgd_lock deadlock from __mmdrop Michal Hocko
2016-08-25 10:03 ` Michal Hocko [this message]
2016-08-25 10:03 ` [PATCH v2 6/9] oom, suspend: fix oom_killer_disable vs. pm suspend properly Michal Hocko
2016-08-25 10:03 ` [PATCH v2 7/9] mm, oom: enforce exit_oom_victim on current task Michal Hocko
2016-08-25 10:03 ` [PATCH v2 8/9] mm: make sure that kthreads will not refault oom reaped memory Michal Hocko
2016-08-25 10:03 ` [PATCH v2 9/9] oom, oom_reaper: allow to reap mm shared by the kthreads Michal Hocko

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=1472119394-11342-6-git-send-email-mhocko@kernel.org \
    --to=mhocko@kernel.org \
    --cc=akpm@linux-foundation.org \
    --cc=linux-mm@kvack.org \
    --cc=mhocko@suse.com \
    --cc=oleg@redhat.com \
    --cc=penguin-kernel@I-love.SAKURA.ne.jp \
    --cc=rientjes@google.com \
    --cc=vdavydov@parallels.com \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body. 
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.