The commit eb4058d8daf8 ("memfd: Fix locking when tagging pins")
introduces the following warning messages.
*WARNING: suspicious RCU usage in memfd_wait_for_pins*
It is because we still use radix_tree_deref_slot without read_rcu_lock.
We should use radix_tree_deref_slot_protected instead in the case.
Cc: stable@xxxxxxxxxxxxxxx
Fixes: eb4058d8daf8 ("memfd: Fix locking when tagging pins")
Signed-off-by: zhong jiang <zhongjiang@xxxxxxxxxx>
---
mm/shmem.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/mm/shmem.c b/mm/shmem.c
index 62668379623b..e40239bf6dfe 100644
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -1862,7 +1862,7 @@ static void shmem_tag_pins(struct address_space *mapping)
spin_lock_irq(&mapping->tree_lock);
restart:
radix_tree_for_each_slot(slot, &mapping->page_tree, &iter, start) {
- page = radix_tree_deref_slot(slot);
+ page = radix_tree_deref_slot_protected(slot, &mapping->tree_lock);
if (!page || radix_tree_exception(page)) {
if (radix_tree_deref_retry(page))
goto restart;
--
2.20.1
