Commit e0088cfb authored Nov 18, 2019 by zhong jiang Committed by Greg Kroah-Hartman Nov 25, 2019

memfd: Use radix_tree_deref_slot_protected to avoid the warning.



The commit 3ce6b467 ("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@vger.kernel.org
Fixes: 3ce6b467 ("memfd: Fix locking when tagging pins")
Signed-off-by: zhong jiang <zhongjiang@huawei.com>
Reviewed-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

parent 6988feec

mm/shmem.c

+1 −1

Original line number	Diff line number	Diff line
		@@ -2464,7 +2464,7 @@ static void shmem_tag_pins(struct address_space *mapping)

		spin_lock_irq(&mapping->tree_lock);
		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)) {
		slot = radix_tree_iter_retry(&iter);