The patch titled
Subject: mm, oom: get rid of signal_struct::oom_victims
has been added to the -mm tree. Its filename is
mm-oom-get-rid-of-signal_struct-oom_victims.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/mm-oom-get-rid-of-signal_struct-oom_victims.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/mm-oom-get-rid-of-signal_struct-oom_victims.patch
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*** Remember to use Documentation/SubmitChecklist when testing your code ***
The -mm tree is included into linux-next and is updated
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------------------------------------------------------
From: Michal Hocko <mhocko@xxxxxxxx>
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@xxxxxxxxxx
Signed-off-by: Michal Hocko <mhocko@xxxxxxxx>
Cc: Tetsuo Handa <penguin-kernel@xxxxxxxxxxxxxxxxxxx>
Cc: Oleg Nesterov <oleg@xxxxxxxxxx>
Cc: David Rientjes <rientjes@xxxxxxxxxx>
Cc: Vladimir Davydov <vdavydov@xxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
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 -puN include/linux/oom.h~mm-oom-get-rid-of-signal_struct-oom_victims include/linux/oom.h
--- a/include/linux/oom.h~mm-oom-get-rid-of-signal_struct-oom_victims
+++ a/include/linux/oom.h
@@ -58,6 +58,11 @@ static inline bool oom_task_origin(const
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 -puN include/linux/sched.h~mm-oom-get-rid-of-signal_struct-oom_victims include/linux/sched.h
--- a/include/linux/sched.h~mm-oom-get-rid-of-signal_struct-oom_victims
+++ a/include/linux/sched.h
@@ -522,7 +522,7 @@ static inline int get_dumpable(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)
@@ -670,7 +670,6 @@ 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 -puN kernel/fork.c~mm-oom-get-rid-of-signal_struct-oom_victims kernel/fork.c
--- a/kernel/fork.c~mm-oom-get-rid-of-signal_struct-oom_victims
+++ a/kernel/fork.c
@@ -725,6 +725,7 @@ static inline void __mmput(struct mm_str
}
if (mm->binfmt)
module_put(mm->binfmt->module);
+ set_bit(MMF_OOM_SKIP, &mm->flags);
mmdrop(mm);
}
diff -puN mm/oom_kill.c~mm-oom-get-rid-of-signal_struct-oom_victims mm/oom_kill.c
--- a/mm/oom_kill.c~mm-oom-get-rid-of-signal_struct-oom_victims
+++ a/mm/oom_kill.c
@@ -186,7 +186,7 @@ unsigned long oom_badness(struct task_st
*/
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
/*
* 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_
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
{
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 ta
* 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_
* 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);
_
Patches currently in -mm which might be from mhocko@xxxxxxxx are
mm-clarify-compaction-kconfig-text.patch
mm-oom-prevent-pre-mature-oom-killer-invocation-for-high-order-request.patch
mm-vmscan-get-rid-of-throttle_vm_writeout.patch
oom-keep-mm-of-the-killed-task-available.patch
kernel-oom-fix-potential-pgd_lock-deadlock-from-__mmdrop.patch
mm-oom-get-rid-of-signal_struct-oom_victims.patch
oom-suspend-fix-oom_killer_disable-vs-pm-suspend-properly.patch
mm-make-sure-that-kthreads-will-not-refault-oom-reaped-memory.patch
oom-oom_reaper-allow-to-reap-mm-shared-by-the-kthreads.patch
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