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memfd: Use radix_tree_deref_slot_protected to avoid the warning.

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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@vger.kernel.org
Fixes: eb4058d8daf8 ("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>
This commit is contained in:
zhong jiang 2019-11-18 11:26:09 +08:00 committed by Greg Kroah-Hartman
parent 29d9c57140
commit 905bf98eb3
1 changed files with 1 additions and 1 deletions
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2
mm/shmem.c
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@ -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;