Messages in this thread Patch in this message | | | From | Greg Kroah-Hartman <> | Subject | [PATCH 4.4 098/159] memfd: Use radix_tree_deref_slot_protected to avoid the warning. | Date | Fri, 22 Nov 2019 11:28:09 +0100 |
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From: zhong jiang <zhongjiang@huawei.com>
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> --- mm/shmem.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
--- a/mm/shmem.c +++ b/mm/shmem.c @@ -1862,7 +1862,7 @@ static void shmem_tag_pins(struct addres 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;
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