From mboxrd@z Thu Jan 1 00:00:00 1970 From: Badari Subject: Re: migratepage failures on reiserfs Date: Tue, 30 Oct 2007 16:08:41 -0700 Message-ID: <4727B979.8030207@us.ibm.com> References: <1193768824.8904.11.camel@dyn9047017100.beaverton.ibm.com> <20071030135442.5d33c61c@think.oraclecorp.com> <1193781245.8904.28.camel@dyn9047017100.beaverton.ibm.com> <20071030185840.48f5a10b@think.oraclecorp.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: reiserfs-devel@vger.kernel.org, linux-mm , linux-fsdevel To: Chris Mason Return-path: In-Reply-To: <20071030185840.48f5a10b@think.oraclecorp.com> Sender: reiserfs-devel-owner@vger.kernel.org List-Id: linux-fsdevel.vger.kernel.org Chris Mason wrote: > On Tue, 30 Oct 2007 13:54:05 -0800 > Badari Pulavarty wrote: > > >> On Tue, 2007-10-30 at 13:54 -0400, Chris Mason wrote: >> >>> On Tue, 30 Oct 2007 10:27:04 -0800 >>> Badari Pulavarty wrote: >>> >>> >>>> Hi, >>>> >>>> While testing hotplug memory remove, I ran into this issue. Given >>>> a range of pages hotplug memory remove tries to migrate those >>>> pages. >>>> >>>> migrate_pages() keeps failing to migrate pages containing >>>> pagecache pages for reiserfs files. I noticed that reiserfs >>>> doesn't have ->migratepage() ops. So, fallback_migrate_page() >>>> code tries to do try_to_release_page(). try_to_release_page() >>>> fails to drop_buffers() since b_count == 1. Here is what my debug >>>> shows: >>>> >>>> migrate pages failed pfn 258111/flags 3f00000000801 >>>> bh c00000000b53f6e0 flags 110029 count 1 >>>> >>>> Any one know why the b_count == 1 and not getting dropped to >>>> zero ? >>>> >>> If these are file data pages, the count is probably elevated as >>> part of the data=ordered tracking. You can verify this via >>> b_private, or just mount data=writeback to double check. >>> >> Chris, >> >> That was my first assumption. But after looking at >> reiserfs_releasepage (), realized that it would do reiserfs_free_jh() >> and clears the b_private. I couldn't easily find out who has the ref. >> against this bh. >> >> bh c00000000bdaaf00 flags 110029 count 1 private 0 >> >> > > If I'm reading this correctly the buffer is BH_Lock | BH_Req, perhaps > it is currently under IO? > Its BH_Req | BH_Uptodate. Its not under IO. > The page isn't locked, but data=ordered does IO directly on the buffer > heads, without taking the page lock. > > The easy way to narrow our search is to try without data=ordered, it is > certainly complicating things. > I can try that, its my root filesystem :( Thanks, Badari