linux-kernel - [PATCH RESEND v2 2/2] mm: delete unused MMF_OOM

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Date:   Tue, 31 May 2022 15:31:00 -0700
From:   Suren Baghdasaryan <surenb@...gle.com>
To:     akpm@...ux-foundation.org
Cc:     mhocko@...e.com, rientjes@...gle.com, willy@...radead.org,
        hannes@...xchg.org, guro@...com, minchan@...nel.org,
        kirill@...temov.name, aarcange@...hat.com, brauner@...nel.org,
        hch@...radead.org, oleg@...hat.com, david@...hat.com,
        jannh@...gle.com, shakeelb@...gle.com, peterx@...hat.com,
        jhubbard@...dia.com, shuah@...nel.org,
        linux-kernel@...r.kernel.org, linux-mm@...ck.org,
        linux-kselftest@...r.kernel.org, kernel-team@...roid.com,
        surenb@...gle.com
Subject: [PATCH RESEND v2 2/2] mm: delete unused MMF_OOM_VICTIM flag

With the last usage of MMF_OOM_VICTIM in exit_mmap gone, this flag is
now unused and can be removed.

Signed-off-by: Suren Baghdasaryan <surenb@...gle.com>
Acked-by: Michal Hocko <mhocko@...e.com>
---
 include/linux/oom.h            | 9 ---------
 include/linux/sched/coredump.h | 7 +++----
 mm/oom_kill.c                  | 4 +---
 3 files changed, 4 insertions(+), 16 deletions(-)

diff --git a/include/linux/oom.h b/include/linux/oom.h
index 6cdde62b078b..7d0c9c48a0c5 100644
--- a/include/linux/oom.h
+++ b/include/linux/oom.h
@@ -77,15 +77,6 @@ static inline bool tsk_is_oom_victim(struct task_struct * tsk)
 	return tsk->signal->oom_mm;
 }
 
-/*
- * Use this helper if tsk->mm != mm and the victim mm needs a special
- * handling. This is guaranteed to stay true after once set.
- */
-static inline bool mm_is_oom_victim(struct mm_struct *mm)
-{
-	return test_bit(MMF_OOM_VICTIM, &mm->flags);
-}
-
 /*
  * Checks whether a page fault on the given mm is still reliable.
  * This is no longer true if the oom reaper started to reap the
diff --git a/include/linux/sched/coredump.h b/include/linux/sched/coredump.h
index 4d0a5be28b70..8270ad7ae14c 100644
--- a/include/linux/sched/coredump.h
+++ b/include/linux/sched/coredump.h
@@ -71,9 +71,8 @@ static inline int get_dumpable(struct mm_struct *mm)
 #define MMF_UNSTABLE		22	/* mm is unstable for copy_from_user */
 #define MMF_HUGE_ZERO_PAGE	23      /* mm has ever used the global huge zero page */
 #define MMF_DISABLE_THP		24	/* disable THP for all VMAs */
-#define MMF_OOM_VICTIM		25	/* mm is the oom victim */
-#define MMF_OOM_REAP_QUEUED	26	/* mm was queued for oom_reaper */
-#define MMF_MULTIPROCESS	27	/* mm is shared between processes */
+#define MMF_OOM_REAP_QUEUED	25	/* mm was queued for oom_reaper */
+#define MMF_MULTIPROCESS	26	/* mm is shared between processes */
 /*
  * MMF_HAS_PINNED: Whether this mm has pinned any pages.  This can be either
  * replaced in the future by mm.pinned_vm when it becomes stable, or grow into
@@ -81,7 +80,7 @@ static inline int get_dumpable(struct mm_struct *mm)
  * pinned pages were unpinned later on, we'll still keep this bit set for the
  * lifecycle of this mm, just for simplicity.
  */
-#define MMF_HAS_PINNED		28	/* FOLL_PIN has run, never cleared */
+#define MMF_HAS_PINNED		27	/* FOLL_PIN has run, never cleared */
 #define MMF_DISABLE_THP_MASK	(1 << MMF_DISABLE_THP)
 
 #define MMF_INIT_MASK		(MMF_DUMPABLE_MASK | MMF_DUMP_FILTER_MASK |\
diff --git a/mm/oom_kill.c b/mm/oom_kill.c
index 98dca2b42357..c6c76c313b39 100644
--- a/mm/oom_kill.c
+++ b/mm/oom_kill.c
@@ -764,10 +764,8 @@ static void mark_oom_victim(struct task_struct *tsk)
 		return;
 
 	/* oom_mm is bound to the signal struct life time. */
-	if (!cmpxchg(&tsk->signal->oom_mm, NULL, mm)) {
+	if (!cmpxchg(&tsk->signal->oom_mm, NULL, mm))
 		mmgrab(tsk->signal->oom_mm);
-		set_bit(MMF_OOM_VICTIM, &mm->flags);
-	}
 
 	/*
 	 * Make sure that the task is woken up from uninterruptible sleep
-- 
2.36.1.255.ge46751e96f-goog