Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1761253AbZDGX13 (ORCPT ); Tue, 7 Apr 2009 19:27:29 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752866AbZDGX1S (ORCPT ); Tue, 7 Apr 2009 19:27:18 -0400 Received: from mga03.intel.com ([143.182.124.21]:38858 "EHLO mga03.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751287AbZDGX1R (ORCPT ); Tue, 7 Apr 2009 19:27:17 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="4.39,340,1235980800"; d="scan'208";a="129009499" Date: Wed, 8 Apr 2009 07:27:00 +0800 From: Wu Fengguang To: Ying Han Cc: Andrew Morton , LKML , "linux-fsdevel@vger.kernel.org" , "linux-mm@kvack.org" Subject: Re: [PATCH 03/14] mm: remove FAULT_FLAG_RETRY dead code Message-ID: <20090407232700.GB5607@localhost> References: <20090407071729.233579162@intel.com> <20090407072133.053995305@intel.com> <604427e00904071303g1d092eabp59fca0713ddacf82@mail.gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <604427e00904071303g1d092eabp59fca0713ddacf82@mail.gmail.com> User-Agent: Mutt/1.5.18 (2008-05-17) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 4323 Lines: 125 On Wed, Apr 08, 2009 at 04:03:36AM +0800, Ying Han wrote: > On Tue, Apr 7, 2009 at 12:17 AM, Wu Fengguang wrote: > > Cc: Ying Han > > Signed-off-by: Wu Fengguang > > --- > > mm/memory.c | 4 +--- > > 1 file changed, 1 insertion(+), 3 deletions(-) > > > > --- mm.orig/mm/memory.c > > +++ mm/mm/memory.c > > @@ -2766,10 +2766,8 @@ static int do_linear_fault(struct mm_str > > { > > pgoff_t pgoff = (((address & PAGE_MASK) > > - vma->vm_start) >> PAGE_SHIFT) + vma->vm_pgoff; > > - int write = write_access & ~FAULT_FLAG_RETRY; > > - unsigned int flags = (write ? FAULT_FLAG_WRITE : 0); > > + unsigned int flags = (write_access ? FAULT_FLAG_WRITE : 0); > > > > - flags |= (write_access & FAULT_FLAG_RETRY); > > pte_unmap(page_table); > > return __do_fault(mm, vma, address, pmd, pgoff, flags, orig_pte); > > } > So, we got rid of FAULT_FLAG_RETRY flag? Seems yes for the current mm tree, see the following two commits. I did this patch on seeing 761fe7bc8193b7. But a closer look indicates that the following two patches disable the filemap VM_FAULT_RETRY part totally... Anyway, if these two patches are to be reverted somehow(I guess yes), this patch shall be _ignored_. btw, do you have any test case and performance numbers for FAULT_FLAG_RETRY? And possible overheads for (the worst case) sparse random mmap reads on a sparse file? I cannot find any in your changelogs.. Thanks, Fengguang commit 761fe7bc8193b7858b7dc7eb4a026dc66e49fe1f Author: Andrew Morton Date: Mon Feb 9 21:08:50 2009 +0100 A shot in the dark :( Cc: Mike Waychison Cc: Ying Han Signed-off-by: Andrew Morton diff --git a/arch/x86/mm/fault.c b/arch/x86/mm/fault.c index bac7d7a..1c6736d 100644 --- a/arch/x86/mm/fault.c +++ b/arch/x86/mm/fault.c @@ -1139,8 +1139,6 @@ good_area: return; } - write |= retry_flag; - /* * If for any reason at all we couldn't handle the fault, * make sure we exit gracefully rather than endlessly redo commit f01ca7a68c37680a4eee22a8722a713c5102b3bb Author: Andrew Morton Date: Mon Feb 9 21:08:50 2009 +0100 Untangle the `write' boolean from the FAULT_FLAG_foo non-boolean field. Cc: "H. Peter Anvin" Cc: Benjamin Herrenschmidt Cc: David Rientjes Cc: Hugh Dickins Cc: Ingo Molnar Cc: Lee Schermerhorn Cc: Mike Waychison Cc: Nick Piggin Cc: Peter Zijlstra Cc: Rohit Seth Cc: Trk Edwin Cc: Valdis.Kletnieks@vt.edu Cc: Ying Han Signed-off-by: Andrew Morton diff --git a/arch/x86/mm/fault.c b/arch/x86/mm/fault.c index b2cc88f..bac7d7a 100644 --- a/arch/x86/mm/fault.c +++ b/arch/x86/mm/fault.c @@ -978,7 +978,7 @@ do_page_fault(struct pt_regs *regs, unsigned long error_code) struct mm_struct *mm; int write; int fault; - unsigned int retry_flag = FAULT_FLAG_RETRY; + int retry_flag = 1; tsk = current; mm = tsk->mm; @@ -1140,6 +1140,7 @@ good_area: } write |= retry_flag; + /* * If for any reason at all we couldn't handle the fault, * make sure we exit gracefully rather than endlessly redo @@ -1159,8 +1160,8 @@ good_area: * be removed or changed after the retry. */ if (fault & VM_FAULT_RETRY) { - if (write & FAULT_FLAG_RETRY) { - retry_flag &= ~FAULT_FLAG_RETRY; + if (retry_flag) { + retry_flag = 0; goto retry; } -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/