From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail144.messagelabs.com (mail144.messagelabs.com [216.82.254.51]) by kanga.kvack.org (Postfix) with ESMTP id 3A5126B0047 for ; Mon, 20 Sep 2010 01:21:36 -0400 (EDT) From: Nikanth Karthikesan Subject: Re: [PATCH v2] After swapout/swapin private dirty mappings are reported clean in smaps Date: Mon, 20 Sep 2010 10:54:01 +0530 References: <20100915134724.C9EE.A69D9226@jp.fujitsu.com> <201009192307.09309.knikanth@suse.de> In-Reply-To: <201009192307.09309.knikanth@suse.de> MIME-Version: 1.0 Content-Type: Text/Plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Message-Id: <201009201054.02143.knikanth@suse.de> 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 Sunday 19 September 2010 23:07:09 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. Or even simpler, /proc/pid/numa_maps already exports the number of anonymous pages in a mapping, if you have CONFIG_NUMA=y! Again not documented in Documentation/filesystems/proc.txt 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