From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Date: Wed, 28 Nov 2018 12:46:25 +0100 From: Jan Kara To: Matthew Wilcox Cc: Dan Williams , Jan Kara , Dave Jiang , linux-nvdimm@lists.01.org, linux-fsdevel@vger.kernel.org, stable@vger.kernel.org Subject: Re: [PATCH 1/2] dax: Check page->mapping isn't NULL Message-ID: <20181128114625.GA15604@quack2.suse.cz> References: <20181127211634.4995-1-willy@infradead.org> <20181127211634.4995-2-willy@infradead.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20181127211634.4995-2-willy@infradead.org> Sender: stable-owner@vger.kernel.org List-ID: On Tue 27-11-18 13:16:33, Matthew Wilcox wrote: > 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 Thanks for writing this fix. The patch looks good. You can add: Reviewed-by: Jan Kara Honza > --- > 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 > -- Jan Kara SUSE Labs, CR