From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from bombadil.infradead.org ([198.137.202.133]:44456 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726623AbeK1IQB (ORCPT ); Wed, 28 Nov 2018 03:16:01 -0500 From: Matthew Wilcox To: Dan Williams Cc: Matthew Wilcox , Jan Kara , Dave Jiang , linux-nvdimm@lists.01.org, linux-fsdevel@vger.kernel.org, stable@vger.kernel.org Subject: [PATCH 1/2] dax: Check page->mapping isn't NULL Date: Tue, 27 Nov 2018 13:16:33 -0800 Message-Id: <20181127211634.4995-2-willy@infradead.org> In-Reply-To: <20181127211634.4995-1-willy@infradead.org> References: <20181127211634.4995-1-willy@infradead.org> Sender: linux-fsdevel-owner@vger.kernel.org List-ID: If we race with inode destroy, it's possible for page->mapping to be NULL before we even enter this routine, as well as after having slept waiting for the dax entry to become unlocked. Fixes: c2a7d2a11552 ("filesystem-dax: Introduce dax_lock_mapping_entry()") Cc: stable@vger.kernel.org Reported-by: Jan Kara Signed-off-by: Matthew Wilcox --- fs/dax.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/fs/dax.c b/fs/dax.c index 9bcce89ea18e..e69fc231833b 100644 --- a/fs/dax.c +++ b/fs/dax.c @@ -365,7 +365,7 @@ bool dax_lock_mapping_entry(struct page *page) struct address_space *mapping = READ_ONCE(page->mapping); locked = false; - if (!dax_mapping(mapping)) + if (!mapping || !dax_mapping(mapping)) break; /* -- 2.19.1