Re: [PATCH] Expose SHM_HUGETLB in shmctl(id, IPC_STAT, ...)

[Arun Sharma <arun.sharma@google.com>]

Andrew Morton wrote:

>> +	shp->shm_flags = (shmflg & (S_IRWXUGO | SHM_HUGETLB));
> [...]
> I dunno.  The manpage says:
> 
>        The highlighted fields in the member shm_perm can be set:
> 
>            struct ipc_perm {
>        ...
>                ushort mode;  /* lower 9 bits of access modes */
>        ...
>            };
> 
> So if an application used to do:
> 
> 	if (perm.mode == 0666)
> 
> it will now break, because we've gone and set bit 9 on hugetlb segments.

The man page on my system says:

               unsigned short mode;  /* Permissions + SHM_DEST and
                                         SHM_LOCKED flags */

I looked for a precendent before sending the patch and thought that 
SHM_LOCKED was a good one.

	-Arun