From mboxrd@z Thu Jan 1 00:00:00 1970 From: Omar Sandoval Subject: Re: [BUG] Oops in inode_to_bdi() Date: Fri, 23 Jan 2015 17:22:09 -0800 Message-ID: <20150124012209.GA4893@mew> References: <20150121191707.GA27823@kernel.dk> <20150121192949.GA24787@infradead.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Jens Axboe , linux-fsdevel@vger.kernel.org To: Christoph Hellwig Return-path: Received: from mail-pa0-f43.google.com ([209.85.220.43]:38792 "EHLO mail-pa0-f43.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751883AbbAXBWN (ORCPT ); Fri, 23 Jan 2015 20:22:13 -0500 Received: by mail-pa0-f43.google.com with SMTP id eu11so428666pac.2 for ; Fri, 23 Jan 2015 17:22:13 -0800 (PST) Content-Disposition: inline In-Reply-To: <20150121192949.GA24787@infradead.org> Sender: linux-fsdevel-owner@vger.kernel.org List-ID: On Wed, Jan 21, 2015 at 11:29:49AM -0800, Christoph Hellwig wrote: > On Wed, Jan 21, 2015 at 12:17:07PM -0700, Jens Axboe wrote: > > Christoph, > > > > Ran into this one while testing. Looks like mapping->host is NULL, off > > the shmem_writepage(). > > Hmm. Not sure how this can happen, but for a NULL inode we can > always just return noop_backing_dev_info safely, I'll cook up a patch. Just in case anyone is still wondering, this happens because for a swapcache page, page_mapping() returns the corresponding address_space out of swapper_spaces, which doesn't have a valid host pointer. Before getting rid of backing_dev_info, we would've used swap_backing_dev_info, which it looks like you replaced with noop_backing_dev_info in your series, so Jens' fix should be right. -- Omar