From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756524Ab0ITOaq (ORCPT ); Mon, 20 Sep 2010 10:30:46 -0400 Received: from cantor.suse.de ([195.135.220.2]:46314 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755221Ab0ITOap (ORCPT ); Mon, 20 Sep 2010 10:30:45 -0400 Date: Mon, 20 Sep 2010 16:30:40 +0200 (CEST) From: Richard Guenther To: Nikanth Karthikesan Cc: Balbir Singh , KOSAKI Motohiro , linux-mm@kvack.org, Andrew Morton , Michael Matz , Matt Mackall , linux-kernel@vger.kernel.org Subject: Re: [PATCH v2] After swapout/swapin private dirty mappings are reported clean in smaps In-Reply-To: <201009192307.09309.knikanth@suse.de> Message-ID: References: <20100915134724.C9EE.A69D9226@jp.fujitsu.com> <20100915140911.GC4383@balbir.in.ibm.com> <201009192307.09309.knikanth@suse.de> User-Agent: Alpine 2.00 (LNX 1167 2008-08-23) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sun, 19 Sep 2010, Nikanth Karthikesan wrote: > 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. Looks like /proc/kpageflags is root-only, so not a solution for gdb. Richard. From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail202.messagelabs.com (mail202.messagelabs.com [216.82.254.227]) by kanga.kvack.org (Postfix) with ESMTP id 74A496B0047 for ; Mon, 20 Sep 2010 10:30:55 -0400 (EDT) Date: Mon, 20 Sep 2010 16:30:40 +0200 (CEST) From: Richard Guenther Subject: Re: [PATCH v2] After swapout/swapin private dirty mappings are reported clean in smaps In-Reply-To: <201009192307.09309.knikanth@suse.de> Message-ID: References: <20100915134724.C9EE.A69D9226@jp.fujitsu.com> <20100915140911.GC4383@balbir.in.ibm.com> <201009192307.09309.knikanth@suse.de> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-linux-mm@kvack.org To: Nikanth Karthikesan Cc: Balbir Singh , KOSAKI Motohiro , linux-mm@kvack.org, Andrew Morton , Michael Matz , Matt Mackall , linux-kernel@vger.kernel.org List-ID: On Sun, 19 Sep 2010, Nikanth Karthikesan wrote: > 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. Looks like /proc/kpageflags is root-only, so not a solution for gdb. Richard. -- 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