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-rw-r--r--include/linux/oom.h2
-rw-r--r--mm/mmap.c30
-rw-r--r--mm/oom_kill.c2
3 files changed, 12 insertions, 22 deletions
diff --git a/include/linux/oom.h b/include/linux/oom.h
index 02d1e7bbd8cd..6cdde62b078b 100644
--- a/include/linux/oom.h
+++ b/include/linux/oom.h
@@ -106,8 +106,6 @@ static inline vm_fault_t check_stable_address_space(struct mm_struct *mm)
 	return 0;
 }
 
-bool __oom_reap_task_mm(struct mm_struct *mm);
-
 long oom_badness(struct task_struct *p,
 		unsigned long totalpages);
 
diff --git a/mm/mmap.c b/mm/mmap.c
index fbe8b52a90a3..be111bbe8075 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -3085,30 +3085,13 @@ void exit_mmap(struct mm_struct *mm)
 	/* mm's last user has gone, and its about to be pulled down */
 	mmu_notifier_release(mm);
 
-	if (unlikely(mm_is_oom_victim(mm))) {
-		/*
-		 * Manually reap the mm to free as much memory as possible.
-		 * Then, as the oom reaper does, set MMF_OOM_SKIP to disregard
-		 * this mm from further consideration.  Taking mm->mmap_lock for
-		 * write after setting MMF_OOM_SKIP will guarantee that the oom
-		 * reaper will not run on this mm again after mmap_lock is
-		 * dropped.
-		 *
-		 * Nothing can be holding mm->mmap_lock here and the above call
-		 * to mmu_notifier_release(mm) ensures mmu notifier callbacks in
-		 * __oom_reap_task_mm() will not block.
-		 */
-		(void)__oom_reap_task_mm(mm);
-		set_bit(MMF_OOM_SKIP, &mm->flags);
-	}
-
-	mmap_write_lock(mm);
+	mmap_read_lock(mm);
 	arch_exit_mmap(mm);
 
 	vma = mas_find(&mas, ULONG_MAX);
 	if (!vma) {
 		/* Can happen if dup_mmap() received an OOM */
-		mmap_write_unlock(mm);
+		mmap_read_unlock(mm);
 		return;
 	}
 
@@ -3118,6 +3101,15 @@ void exit_mmap(struct mm_struct *mm)
 	/* update_hiwater_rss(mm) here? but nobody should be looking */
 	/* Use ULONG_MAX here to ensure all VMAs in the mm are unmapped */
 	unmap_vmas(&tlb, &mm->mm_mt, vma, 0, ULONG_MAX);
+	mmap_read_unlock(mm);
+
+	/*
+	 * Set MMF_OOM_SKIP to hide this task from the oom killer/reaper
+	 * because the memory has been already freed. Do not bother checking
+	 * mm_is_oom_victim because setting a bit unconditionally is cheaper.
+	 */
+	set_bit(MMF_OOM_SKIP, &mm->flags);
+	mmap_write_lock(mm);
 	free_pgtables(&tlb, &mm->mm_mt, vma, FIRST_USER_ADDRESS,
 		      USER_PGTABLES_CEILING);
 	tlb_finish_mmu(&tlb);
diff --git a/mm/oom_kill.c b/mm/oom_kill.c
index 3996301450e8..decb21474c6c 100644
--- a/mm/oom_kill.c
+++ b/mm/oom_kill.c
@@ -509,7 +509,7 @@ static DECLARE_WAIT_QUEUE_HEAD(oom_reaper_wait);
 static struct task_struct *oom_reaper_list;
 static DEFINE_SPINLOCK(oom_reaper_lock);
 
-bool __oom_reap_task_mm(struct mm_struct *mm)
+static bool __oom_reap_task_mm(struct mm_struct *mm)
 {
 	struct vm_area_struct *vma;
 	bool ret = true;