From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Thu, 7 Jun 2007 12:48:24 -0700 From: Andrew Morton Subject: Re: [RFC][PATCH] /proc/pid/maps doesn't match "ipcs -m" shmid Message-Id: <20070607124824.27e909fd.akpm@linux-foundation.org> In-Reply-To: <1181235997.9995.23.camel@dyn9047017100.beaverton.ibm.com> References: <787b0d920706062027s5a8fd35q752f8da5d446afc@mail.gmail.com> <20070606204432.b670a7b1.akpm@linux-foundation.org> <787b0d920706062153u7ad64179p1c4f3f663c3882f@mail.gmail.com> <1181233393.9995.14.camel@dyn9047017100.beaverton.ibm.com> <787b0d920706070943h6ac65b85nee5b01600905be08@mail.gmail.com> <1181235997.9995.23.camel@dyn9047017100.beaverton.ibm.com> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org Return-Path: To: Badari Pulavarty Cc: Albert Cahalan , lkml , linux-mm , ebiederm@xmission.com, torvalds@linux-foundation.org List-ID: On Thu, 07 Jun 2007 10:06:37 -0700 Badari Pulavarty wrote: > On Thu, 2007-06-07 at 12:43 -0400, Albert Cahalan wrote: > > On 6/7/07, Badari Pulavarty wrote: > > > > > BTW, I agree with Eric that its would be nice to use shmid as part > > > of name instead of forcing to be as inode number. It should be > > > possible for pmap to workout shmid from "key" or name. Isn't it ? > > > > It is not at all nice. > > > > 1. it's incompatible ABI breakage > > 2. where will you put the key then, in the inode? :-) > > Nope. Currently "key" is part of the name (but its not unique). > > > > > Changing to "SYSVID%d" is no good either. Look, people > > are ***parsing*** this stuff in /proc. The /proc filesystem > > is not some random sandbox to be playing in. > > > > Before you go messing with it, note that the device number > > also matters. (it's per-boot dynamic, but that's OK) > > That's how one knows that /SYSV00000000 is not just > > a regular file; sadly these didn't get a non-/ prefix. > > (and no you can't fix that now; it's way too late) > > > > Next time you feel like breaking an ABI, mind putting > > "LET'S BREAK AN ABI!" in the subject of your email? > > I am not breaking ABI. Its already broken in the current > mainline. I am trying to fix it by putting back the ino# > as shmid. Eric had a suggestion that, instead of depending > on the inode# to be shmid, we could embed shmid into name > (instead of "key" which is currently not unique). > > > BTW, I suspect this kind of thing also breaks: > > a. fuser, lsof, and other resource usage display tools > > b. various obscure emulators (similar to valgrind) > > If you strongly feel that "old" behaviour needs to be retained, yup, we should put it back. The change was, afaik, accidental. > here is the patch I originally suggested. Confused. Will this one-liner fix all the userspace breakage to which Albert refers? > Thanks, > Badari > > "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. > > Signed-off-by: Badari Pulavarty > > Index: linux-2.6.22-rc4/ipc/shm.c > =================================================================== > --- linux-2.6.22-rc4.orig/ipc/shm.c 2007-06-04 17:57:25.000000000 -0700 > +++ linux-2.6.22-rc4/ipc/shm.c 2007-06-06 08:23:57.000000000 -0700 > @@ -397,6 +397,7 @@ static int newseg (struct ipc_namespace > shp->shm_nattch = 0; > shp->id = shm_buildid(ns, id, shp->shm_perm.seq); > shp->shm_file = file; > + file->f_dentry->d_inode->i_ino = shp->id; > > ns->shm_tot += numpages; > shm_unlock(shp); > > -- 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