From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755499Ab0ITDxs (ORCPT ); Sun, 19 Sep 2010 23:53:48 -0400 Received: from victor.provo.novell.com ([137.65.250.26]:34119 "EHLO victor.provo.novell.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755363Ab0ITDxr (ORCPT ); Sun, 19 Sep 2010 23:53:47 -0400 X-Greylist: delayed 1202 seconds by postgrey-1.27 at vger.kernel.org; Sun, 19 Sep 2010 23:53:47 EDT From: Nikanth Karthikesan Organization: suse.de To: Richard Guenther Subject: Re: [PATCH v2] After swapout/swapin private dirty mappings are reported clean in smaps Date: Sun, 19 Sep 2010 23:07:09 +0530 User-Agent: KMail/1.12.4 (Linux/2.6.31.12-0.2-default; KDE/4.3.5; x86_64; ; ) Cc: Balbir Singh , KOSAKI Motohiro , linux-mm@kvack.org, Andrew Morton , Michael Matz , Matt Mackall , linux-kernel@vger.kernel.org References: <20100915134724.C9EE.A69D9226@jp.fujitsu.com> <20100915140911.GC4383@balbir.in.ibm.com> In-Reply-To: MIME-Version: 1.0 Message-Id: <201009192307.09309.knikanth@suse.de> Content-Type: Text/Plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wednesday 15 September 2010 19:44:17 Richard Guenther wrote: > On Wed, 15 Sep 2010, Balbir Singh wrote: > > * Nikanth Karthikesan [2010-09-15 12:01:11]: > > > How? Current smaps information without this patch provides incorrect > > > information. Just because a private dirty page became part of swap > > > cache, it shown as clean and backed by a file. If it is shown as clean > > > and backed by swap then it is fine. > > > > How is GDB using this information? > > GDB counts the number of dirty and swapped pages in a private mapping and > based on that decides whether it needs to dump it to a core file or not. > If there are no dirty or swapped pages gdb assumes it can reconstruct > the mapping from the original backing file. This way for example > shared libraries do not end up in the core file. > Well, may be /proc/pid/pagemap + /proc/kpageflags is enough for this! One can get the pageflags using these interfaces. See Documentation/vm/pagemap.txt for the explanation on how to do it. There is also a sample program that prints page flags using this interface in Documentation/vm/page-types.c. It is bad that /proc/pid/pagemap is never mentioned in Documentation/filesystems/proc.txt. I will send a patch to rectify this. Thanks Nikanth 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 DB4196B007B for ; Sun, 19 Sep 2010 23:33:46 -0400 (EDT) From: Nikanth Karthikesan Subject: Re: [PATCH v2] After swapout/swapin private dirty mappings are reported clean in smaps Date: Sun, 19 Sep 2010 23:07:09 +0530 References: <20100915134724.C9EE.A69D9226@jp.fujitsu.com> <20100915140911.GC4383@balbir.in.ibm.com> In-Reply-To: MIME-Version: 1.0 Message-Id: <201009192307.09309.knikanth@suse.de> Content-Type: Text/Plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org To: Richard Guenther Cc: Balbir Singh , KOSAKI Motohiro , linux-mm@kvack.org, Andrew Morton , Michael Matz , Matt Mackall , linux-kernel@vger.kernel.org List-ID: On Wednesday 15 September 2010 19:44:17 Richard Guenther wrote: > On Wed, 15 Sep 2010, Balbir Singh wrote: > > * Nikanth Karthikesan [2010-09-15 12:01:11]: > > > How? Current smaps information without this patch provides incorrect > > > information. Just because a private dirty page became part of swap > > > cache, it shown as clean and backed by a file. If it is shown as clean > > > and backed by swap then it is fine. > > > > How is GDB using this information? > > GDB counts the number of dirty and swapped pages in a private mapping and > based on that decides whether it needs to dump it to a core file or not. > If there are no dirty or swapped pages gdb assumes it can reconstruct > the mapping from the original backing file. This way for example > shared libraries do not end up in the core file. > Well, may be /proc/pid/pagemap + /proc/kpageflags is enough for this! One can get the pageflags using these interfaces. See Documentation/vm/pagemap.txt for the explanation on how to do it. There is also a sample program that prints page flags using this interface in Documentation/vm/page-types.c. It is bad that /proc/pid/pagemap is never mentioned in Documentation/filesystems/proc.txt. I will send a patch to rectify this. Thanks Nikanth -- 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