From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Tue, 30 Oct 2007 13:54:42 -0400 From: Chris Mason Subject: Re: migratepage failures on reiserfs Message-ID: <20071030135442.5d33c61c@think.oraclecorp.com> In-Reply-To: <1193768824.8904.11.camel@dyn9047017100.beaverton.ibm.com> References: <1193768824.8904.11.camel@dyn9047017100.beaverton.ibm.com> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org Return-Path: To: Badari Pulavarty Cc: reiserfs-devel@vger.kernel.org, linux-mm , linux-fsdevel List-ID: 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 -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org