From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail138.messagelabs.com (mail138.messagelabs.com [216.82.249.35]) by kanga.kvack.org (Postfix) with ESMTP id 32E836B004F for ; Tue, 9 Jun 2009 05:20:43 -0400 (EDT) Date: Tue, 9 Jun 2009 11:51:55 +0200 From: Nick Piggin Subject: Re: [PATCH] [13/16] HWPOISON: The high level memory error handler in the VM v5 Message-ID: <20090609095155.GA14820@wotan.suse.de> References: <20090603846.816684333@firstfloor.org> <20090603184648.2E2131D028F@basil.firstfloor.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20090603184648.2E2131D028F@basil.firstfloor.org> Sender: owner-linux-mm@kvack.org To: Andi Kleen Cc: hugh.dickins@tiscali.co.uk, riel@redhat.com, chris.mason@oracle.com, akpm@linux-foundation.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, fengguang.wu@intel.com, linux-fsdevel@vger.kernel.org List-ID: On Wed, Jun 03, 2009 at 08:46:47PM +0200, Andi Kleen wrote: > +static int me_pagecache_clean(struct page *p, unsigned long pfn) > +{ > + struct address_space *mapping; > + > + if (!isolate_lru_page(p)) > + page_cache_release(p); > + > + /* > + * Now truncate the page in the page cache. This is really > + * more like a "temporary hole punch" > + * Don't do this for block devices when someone else > + * has a reference, because it could be file system metadata > + * and that's not safe to truncate. > + */ > + mapping = page_mapping(p); > + if (mapping && S_ISBLK(mapping->host->i_mode) && page_count(p) > 1) { > + printk(KERN_ERR > + "MCE %#lx: page looks like a unsupported file system metadata page\n", > + pfn); > + return FAILED; > + } page_count check is racy. Hmm, S_ISBLK should handle xfs's private mapping. AFAIK btrfs has a similar private mapping but a quick grep does not show up S_IFBLK anywhere, so I don't know what the situation is there. Unfortunately though, the linear mapping is not the only metadata mapping a filesystem might have. Many work on directories in seperate mappings (ext2, for example, which is where I first looked and will still oops with your check). Also, others may have other interesting inodes they use for metadata. Do any of them go through the pagecache? I dont know. The ext3 journal, for example? How does that work? Unfortunately I don't know a good way to detect regular data mappings easily. Ccing linux-fsdevel. Until that is worked out, you'd need to use the safe pagecache invalidate rather than unsafe truncate. > + if (mapping) { > + truncate_inode_page(mapping, p); > + if (page_has_private(p) && !try_to_release_page(p, GFP_NOIO)) { > + pr_debug(KERN_ERR "MCE %#lx: failed to release buffers\n", > + pfn); > + return FAILED; > + } > + } > + return RECOVERED; > +} -- 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