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-rw-r--r--lib/is_single_threaded.c10
1 files changed, 6 insertions, 4 deletions
diff --git a/lib/is_single_threaded.c b/lib/is_single_threaded.c
index 434010980bd..bd2bea96336 100644
--- a/lib/is_single_threaded.c
+++ b/lib/is_single_threaded.c
@@ -22,8 +22,6 @@ bool current_is_single_threaded(void)
struct task_struct *p, *t;
bool ret;
- might_sleep();
-
if (atomic_read(&task->signal->live) != 1)
return false;
@@ -31,7 +29,6 @@ bool current_is_single_threaded(void)
return true;
ret = false;
- down_write(&mm->mmap_sem);
rcu_read_lock();
for_each_process(p) {
if (unlikely(p->flags & PF_KTHREAD))
@@ -45,12 +42,17 @@ bool current_is_single_threaded(void)
goto found;
if (likely(t->mm))
break;
+ /*
+ * t->mm == NULL. Make sure next_thread/next_task
+ * will see other CLONE_VM tasks which might be
+ * forked before exiting.
+ */
+ smp_rmb();
} while_each_thread(p, t);
}
ret = true;
found:
rcu_read_unlock();
- up_write(&mm->mmap_sem);
return ret;
}