Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1760908AbXFFREW (ORCPT ); Wed, 6 Jun 2007 13:04:22 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751762AbXFFREP (ORCPT ); Wed, 6 Jun 2007 13:04:15 -0400 Received: from ebiederm.dsl.xmission.com ([166.70.28.69]:58339 "EHLO ebiederm.dsl.xmission.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751124AbXFFREO (ORCPT ); Wed, 6 Jun 2007 13:04:14 -0400 From: ebiederm@xmission.com (Eric W. Biederman) To: Badari Pulavarty Cc: Andrew Morton , linux-mm , lkml Subject: Re: [RFC][PATCH] /proc/pid/maps doesn't match "ipcs -m" shmid References: <1181146045.9503.67.camel@dyn9047017100.beaverton.ibm.com> Date: Wed, 06 Jun 2007 11:02:55 -0600 In-Reply-To: <1181146045.9503.67.camel@dyn9047017100.beaverton.ibm.com> (Badari Pulavarty's message of "Wed, 06 Jun 2007 09:07:24 -0700") Message-ID: User-Agent: Gnus/5.110006 (No Gnus v0.6) Emacs/21.4 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3668 Lines: 104 Badari Pulavarty writes: > Hi Eric, > > Your recent cleanup to shm code, namely > > [PATCH] shm: make sysv ipc shared memory use stacked files > > took away one of the debugging feature for shm segments. > Originally, shmid were forced to be the inode numbers and > they show up in /proc/pid/maps for the process which mapped > this shared memory segments (vma listing). That way, its easy > to find out who all mapped this shared memory segment. Your > patchset, took away the inode# setting. So, we can't easily > match the shmem segments to /proc/pid/maps easily. (It was > really useful in tracking down a customer problem recently). > Is this done deliberately ? Anything wrong in setting this back ? > > Comments ? > > Thanks, > Badari > > Without patch: > -------------- > > # ipcs -m > > ------ Shared Memory Segments -------- > key shmid owner perms bytes nattch status > 0x00000000 884737 db2inst1 767 33554432 13 > > # grep 884737 /proc/*/maps > # > > With patch: > ----------- > > # ipcs -m > > ------ Shared Memory Segments -------- > key shmid owner perms bytes nattch status > 0x00000000 884737 db2inst1 767 33554432 13 > > # grep 884737 /proc/*/maps > /proc/11110/maps:40006724000-40008724000 rw-s 00000000 00:08 884737 > /SYSV00000000 (deleted) > /proc/11111/maps:40006724000-40008724000 rw-s 00000000 00:08 884737 > /SYSV00000000 (deleted) > /proc/11112/maps:40006724000-40008724000 rw-s 00000000 00:08 884737 > /SYSV00000000 (deleted) > /proc/11113/maps:40006724000-40008724000 rw-s 00000000 00:08 884737 > /SYSV00000000 (deleted) > /proc/11114/maps:40006724000-40008724000 rw-s 00000000 00:08 884737 > /SYSV00000000 (deleted) > /proc/11115/maps:40006724000-40008724000 rw-s 00000000 00:08 884737 > /SYSV00000000 (deleted) > /proc/11116/maps:40006724000-40008724000 rw-s 00000000 00:08 884737 > /SYSV00000000 (deleted) > /proc/11117/maps:40006724000-40008724000 rw-s 00000000 00:08 884737 > /SYSV00000000 (deleted) > /proc/11118/maps:40006724000-40008724000 rw-s 00000000 00:08 884737 > /SYSV00000000 (deleted) > /proc/11121/maps:40006724000-40008724000 rw-s 00000000 00:08 884737 > /SYSV00000000 (deleted) > /proc/11122/maps:40006724000-40008724000 rw-s 00000000 00:08 884737 > /SYSV00000000 (deleted) > /proc/11124/maps:4000389c000-4000589c000 rw-s 00000000 00:08 884737 > /SYSV00000000 (deleted) > /proc/11575/maps:40006724000-40008724000 rw-s 00000000 00:08 884737 > /SYSV00000000 (deleted) > > > > Here is the patch. > > "ino#" in /proc/pid/maps used to match "ipcs -m" output for shared > memory (shmid). It was useful in debugging, but its changed recently. > This patch sets inode number to shared memory id to match /proc/pid/maps. Theoretically it makes the stacked file concept more brittle, because it means the lower layers can't care about their inode number. We do need something to tie these things together. So I suspect what makes most sense is to simply rename the dentry SYSVID That should give you the necessary information while not doing something that is a long term maintenance problem. Do you think you can cook up a patch to that effect? Otherwise I will see if I can. In practice I'm not really against your change, but I would prefer to leave the code in a state where someone can reimplement hugetlbfs or shmfs and we simply don't care. Eric - 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/