kernel/fork: assert no VMA readers during its destruction

Assert there are no holders of VMA lock for reading when it is about to be
destroyed.

Link: https://lkml.kernel.org/r/20230227173632.3292573-21-surenb@google.com
Signed-off-by: Suren Baghdasaryan <surenb@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/kernel/fork.c b/kernel/fork.c
index 0907776d8ed43105e7e40ce1f50a46229ad42764..76fcc08984d4a0a7ba7acead9bd22349f23fcacd 100644 (file)
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -491,6 +491,9 @@ static void vm_area_free_rcu_cb(struct rcu_head *head)
 {
        struct vm_area_struct *vma = container_of(head, struct vm_area_struct,
                                                  vm_rcu);
+
+       /* The vma should not be locked while being destroyed. */
+       VM_BUG_ON_VMA(rwsem_is_locked(&vma->lock), vma);
        __vm_area_free(vma);
 }
 #endif