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-rw-r--r--kernel/exit.c9
1 files changed, 4 insertions, 5 deletions
diff --git a/kernel/exit.c b/kernel/exit.c
index 85a83c831856..0ef4673e351b 100644
--- a/kernel/exit.c
+++ b/kernel/exit.c
@@ -640,24 +640,23 @@ retry:
assign_new_owner:
BUG_ON(c == p);
get_task_struct(c);
+ read_unlock(&tasklist_lock);
+ down_write(&mm->mmap_sem);
/*
* The task_lock protects c->mm from changing.
* We always want mm->owner->mm == mm
*/
task_lock(c);
- /*
- * Delay read_unlock() till we have the task_lock()
- * to ensure that c does not slip away underneath us
- */
- read_unlock(&tasklist_lock);
if (c->mm != mm) {
task_unlock(c);
+ up_write(&mm->mmap_sem);
put_task_struct(c);
goto retry;
}
cgroup_mm_owner_callbacks(mm->owner, c);
mm->owner = c;
task_unlock(c);
+ up_write(&mm->mmap_sem);
put_task_struct(c);
}
#endif /* CONFIG_MM_OWNER */