Re: [RFC][PATCH] /proc/pid/maps doesn't match "ipcs -m" shmid

From: Albert Cahalan
Date: Fri Jun 08 2007 - 00:41:54 EST


On 6/7/07, Eric W. Biederman <ebiederm@xxxxxxxxxxxx> wrote:

So it looks to me like we need to do three things:
- Fix the inode number
- Fix the name on the hugetlbfs dentry to hold the key
- Add a big fat comment that user space programs depend on this
behavior of both the dentry name and the inode number.

Assuming that this proposed fix goes in:

Since the inode number is the shmid, and this is a number
that the kernel randomly chooses AFAIK, there should be
no need to have different shm segments sharing the same
inode number.

The situation with the key is a bit more disturbing, though
we already hit that anyway when IPC_PRIVATE is used.
(why anybody would NOT use IPC_PRIVATE is a mystery)
So having the key in the name doesn't make things worse.

I have some concern about the device minor number.
This should be the same for all shm mappings; I do not
know if the behavior changed.
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