From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1161624AbXD3A1J (ORCPT ); Sun, 29 Apr 2007 20:27:09 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1161625AbXD3A1J (ORCPT ); Sun, 29 Apr 2007 20:27:09 -0400 Received: from smtp-out.google.com ([216.239.45.13]:61400 "EHLO smtp-out.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1161624AbXD3A1G (ORCPT ); Sun, 29 Apr 2007 20:27:06 -0400 DomainKey-Signature: a=rsa-sha1; s=beta; d=google.com; c=nofws; q=dns; h=received:message-id:date:from:user-agent:mime-version:to:cc: subject:references:in-reply-to:content-type:content-transfer-encoding; b=D1yMR7RHiOGyV4r45MLuR2U/qTS4WGky0R1b8Biv6XsmNgfpPc8hdB8Pk0QgIYjtU GDiuLzRE4LwnlxcGc5uIA== Message-ID: <463537C2.5050804@google.com> Date: Sun, 29 Apr 2007 17:26:42 -0700 From: Ethan Solomita User-Agent: Thunderbird 1.5.0.10 (Windows/20070221) MIME-Version: 1.0 To: Trond Myklebust CC: LKML , linux-mm@kvack.org Subject: Re: NR_UNSTABLE_FS vs. NR_FILE_DIRTY: double counting pages? References: <4632A1A6.90702@google.com> <1177878135.6400.37.camel@heimdal.trondhjem.org> In-Reply-To: <1177878135.6400.37.camel@heimdal.trondhjem.org> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Trond Myklebust wrote: > On Fri, 2007-04-27 at 18:21 -0700, Ethan Solomita wrote: >> There are several places where we add together NR_UNSTABLE_FS and >> NF_FILE_DIRTY: >> >> sync_inodes_sb() >> balance_dirty_pages() >> wakeup_pdflush() >> wb_kupdate() >> prefetch_suitable() >> >> I can trace a standard codepath where it seems both of these are set >> on the same page: >> >> nfs_file_aops.commit_write -> >> nfs_commit_write >> nfs_updatepages >> nfs_writepage_setup >> nfs_wb_page >> nfs_wb_page_priority >> nfs_writepage_locked >> nfs_flush_mapping >> nfs_flush_list >> nfs_flush_multi >> nfs_write_partial_ops.rpc_call_done >> nfs_writeback_done_partial >> nfs_writepage_release >> nfs_reschedule_unstable_write >> nfs_mark_request_commit >> incr NR_UNSTABLE_NFS >> >> nfs_file_aops.commit_write -> >> nfs_commit_write >> nfs_updatepage >> __set_page_dirty_nobuffers >> incr NF_FILE_DIRTY >> >> >> This is the standard code path that derives from sys_write(). Can >> someone either show how this code sequence can't happen, or confirm for >> me that there's a bug? >> -- Ethan > > It should not happen. If the page is on the unstable list, then it will > be committed before nfs_updatepage is allowed to redirty it. See the > recent fixes in 2.6.21-rc7. Above I present a codepath called straight from sys_write() which seems to do what I say. I could be wrong, but can you address the code paths I show above which seem to set both? -- Ethan