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From: Badari Pulavarty <pbadari@us.ibm.com>
To: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: "Serge E. Hallyn" <serge@hallyn.com>,
	Albert Cahalan <acahalan@gmail.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	linux-kernel@vger.kernel.org, linux-mm@kvack.org,
	torvalds@linux-foundation.org
Subject: Re: [RFC][PATCH] /proc/pid/maps doesn't match "ipcs -m" shmid
Date: Fri, 08 Jun 2007 09:07:54 -0700	[thread overview]
Message-ID: <46697EDA.9000209@us.ibm.com> (raw)
In-Reply-To: m1ir9zrtwe.fsf@ebiederm.dsl.xmission.com



Eric W. Biederman wrote:

>
>At this point given that we actually have a small user space dependency
>and the fact that after I have reviewed the code it looks harmless to
>change the inode number of those inodes, in both cases they are just
>anonymous inodes generated with new_inode, and anything that we wrap
>is likely to be equally so.
>
>So it looks to me like we need to do three things:
>- Fix the inode number
>
Okay. its already done.

>
>- Fix the name on the hugetlbfs dentry to hold the key
>
I don't see need for doing this for hugetlbfs inodes. Currently, they 
don't base their
name on "key" + basing on the "key" is kind of useless anyway (its not 
unique).

>
>- Add a big fat comment that user space programs depend on this
>  behavior of both the dentry name and the inode number.
>
I don't think, the user-space can depend on the dentry-name. It can only 
depend
on inode# to match shmid. (since key is not unique esp. for key=0x00000000).

BTW, I agree that shmid is not unique even without namespaces as its 
based on
seq# and we wrap seq#.

Thanks,
Badari





WARNING: multiple messages have this Message-ID (diff)
From: Badari Pulavarty <pbadari@us.ibm.com>
To: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: "Serge E. Hallyn" <serge@hallyn.com>,
	Albert Cahalan <acahalan@gmail.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	linux-kernel@vger.kernel.org, linux-mm@kvack.org,
	torvalds@linux-foundation.org
Subject: Re: [RFC][PATCH] /proc/pid/maps doesn't match "ipcs -m" shmid
Date: Fri, 08 Jun 2007 09:07:54 -0700	[thread overview]
Message-ID: <46697EDA.9000209@us.ibm.com> (raw)
In-Reply-To: m1ir9zrtwe.fsf@ebiederm.dsl.xmission.com


Eric W. Biederman wrote:

>
>At this point given that we actually have a small user space dependency
>and the fact that after I have reviewed the code it looks harmless to
>change the inode number of those inodes, in both cases they are just
>anonymous inodes generated with new_inode, and anything that we wrap
>is likely to be equally so.
>
>So it looks to me like we need to do three things:
>- Fix the inode number
>
Okay. its already done.

>
>- Fix the name on the hugetlbfs dentry to hold the key
>
I don't see need for doing this for hugetlbfs inodes. Currently, they 
don't base their
name on "key" + basing on the "key" is kind of useless anyway (its not 
unique).

>
>- Add a big fat comment that user space programs depend on this
>  behavior of both the dentry name and the inode number.
>
I don't think, the user-space can depend on the dentry-name. It can only 
depend
on inode# to match shmid. (since key is not unique esp. for key=0x00000000).

BTW, I agree that shmid is not unique even without namespaces as its 
based on
seq# and we wrap seq#.

Thanks,
Badari




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  parent reply	other threads:[~2007-06-08 16:08 UTC|newest]

Thread overview: 68+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2007-06-07  3:27 [RFC][PATCH] /proc/pid/maps doesn't match "ipcs -m" shmid Albert Cahalan
2007-06-07  3:27 ` Albert Cahalan
2007-06-07  3:44 ` Andrew Morton
2007-06-07  3:44   ` Andrew Morton
2007-06-07  4:53   ` Albert Cahalan
2007-06-07  4:53     ` Albert Cahalan
2007-06-07 16:20     ` Serge E. Hallyn
2007-06-07 16:20       ` Serge E. Hallyn
2007-06-08  3:45       ` Eric W. Biederman
2007-06-08  3:45         ` Eric W. Biederman
2007-06-08  4:41         ` Albert Cahalan
2007-06-08  4:41           ` Albert Cahalan
2007-06-08  5:55           ` Eric W. Biederman
2007-06-08  5:55             ` Eric W. Biederman
2007-06-08  6:51             ` Albert Cahalan
2007-06-08  6:51               ` Albert Cahalan
2007-06-08 22:31               ` [PATCH] Restore shmid as inode# to fix /proc/pid/maps ABI breakage Badari Pulavarty
2007-06-08 22:31                 ` Badari Pulavarty
2007-06-08 16:07         ` Badari Pulavarty [this message]
2007-06-08 16:07           ` [RFC][PATCH] /proc/pid/maps doesn't match "ipcs -m" shmid Badari Pulavarty
2007-06-08 23:43           ` [PATCH] shm: Fix the filename of hugetlb sysv shared memory Eric W. Biederman
2007-06-08 23:43             ` Eric W. Biederman
2007-06-08 23:55             ` Andrew Morton
2007-06-08 23:55               ` Andrew Morton
2007-06-09  4:32               ` Badari Pulavarty
2007-06-09  4:32                 ` Badari Pulavarty
2007-06-09  8:01                 ` Eric W. Biederman
2007-06-09  8:01                   ` Eric W. Biederman
2007-06-11 18:11             ` Andrew Morton
2007-06-11 18:11               ` Andrew Morton
2007-06-11 19:55               ` Badari Pulavarty
2007-06-11 19:55                 ` Badari Pulavarty
2007-06-11 19:00             ` Adam Litke
2007-06-11 19:00               ` Adam Litke
2007-06-11 20:53               ` Ken Chen
2007-06-11 20:53                 ` Ken Chen
2007-06-07 16:23     ` [RFC][PATCH] /proc/pid/maps doesn't match "ipcs -m" shmid Badari Pulavarty
2007-06-07 16:23       ` Badari Pulavarty
2007-06-07 16:43       ` Albert Cahalan
2007-06-07 16:43         ` Albert Cahalan
2007-06-07 17:06         ` Badari Pulavarty
2007-06-07 17:06           ` Badari Pulavarty
2007-06-07 19:48           ` Andrew Morton
2007-06-07 19:48             ` Andrew Morton
2007-06-07 19:59             ` Badari Pulavarty
2007-06-07 19:59               ` Badari Pulavarty
2007-06-07 20:37               ` Serge E. Hallyn
2007-06-07 20:37                 ` Serge E. Hallyn
2007-06-07 20:51                 ` Serge E. Hallyn
2007-06-07 20:51                   ` Serge E. Hallyn
2007-06-07 21:16                 ` Badari Pulavarty
2007-06-07 21:16                   ` Badari Pulavarty
2007-06-07 22:08                   ` Serge E. Hallyn
2007-06-07 22:08                     ` Serge E. Hallyn
2007-06-07 22:21                     ` Badari Pulavarty
2007-06-07 22:21                       ` Badari Pulavarty
2007-06-07 22:22                     ` Serge E. Hallyn
2007-06-07 22:22                       ` Serge E. Hallyn
2007-06-07 23:57                       ` Badari Pulavarty
2007-06-07 23:57                         ` Badari Pulavarty
  -- strict thread matches above, loose matches on Subject: below --
2007-06-06 16:07 Badari Pulavarty
2007-06-06 16:07 ` Badari Pulavarty
2007-06-06 17:02 ` Eric W. Biederman
2007-06-06 17:02   ` Eric W. Biederman
2007-06-06 17:37   ` Badari Pulavarty
2007-06-06 17:37     ` Badari Pulavarty
2007-06-06 18:24     ` Eric W. Biederman
2007-06-06 18:24       ` Eric W. Biederman

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