Re: [PATCH 4.9] memfd: Use radix_tree_deref_slot_protected to avoid the warning.

On Mon, Nov 18, 2019 at 11:26:10AM +0800, zhong jiang wrote:

The commit 3ce6b467b9b2 ("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: 3ce6b467b9b2 ("memfd: Fix locking when tagging pins") Signed-off-by: zhong jiang zhongjiang@huawei.com

Reviewed-by: Matthew Wilcox (Oracle) willy@infradead.org