Merge tag 'mtd/for-5.11' of git://git.kernel.org/pub/scm/linux/kernel/git/mtd/linux

[linux-2.6-microblaze.git] / kernel / exit.c

diff --git a/kernel/exit.c b/kernel/exit.c
index 1f236ed..3594291 100644 (file)
--- a/kernel/exit.c
+++ b/kernel/exit.c
@@ -478,10 +478,24 @@ static void exit_mm(void)
        BUG_ON(mm != current->active_mm);
        /* more a memory barrier than a real lock */
        task_lock(current);
+       /*
+        * When a thread stops operating on an address space, the loop
+        * in membarrier_private_expedited() may not observe that
+        * tsk->mm, and the loop in membarrier_global_expedited() may
+        * not observe a MEMBARRIER_STATE_GLOBAL_EXPEDITED
+        * rq->membarrier_state, so those would not issue an IPI.
+        * Membarrier requires a memory barrier after accessing
+        * user-space memory, before clearing tsk->mm or the
+        * rq->membarrier_state.
+        */
+       smp_mb__after_spinlock();
+       local_irq_disable();
        current->mm = NULL;
-       mmap_read_unlock(mm);
+       membarrier_update_current_mm(NULL);
        enter_lazy_tlb(mm, current);
+       local_irq_enable();
        task_unlock(current);
+       mmap_read_unlock(mm);
        mm_update_next_owner(mm);
        mmput(mm);
        if (test_thread_flag(TIF_MEMDIE))