Re: [PATCH, RFC, v2] shmat: introduce flag SHM_MAP_HINT

[Andi Kleen <andi@firstfloor.org>]

On Tue, Oct 07, 2008 at 09:57:50AM +0300, Kirill A. Shutemov wrote:
> It allows interpret attach address as a hint, not as exact address.

Please expand the description a bit. Rationale. etc.

> @@ -55,6 +55,7 @@ struct shmid_ds {
>  #define	SHM_RND		020000	/* round attach address to SHMLBA boundary */
>  #define	SHM_REMAP	040000	/* take-over region on attach */
>  #define	SHM_EXEC	0100000	/* execution access */
> +#define	SHM_MAP_HINT	0200000	/* interpret attach address as a hint */

search hint

> @@ -892,7 +892,7 @@ long do_shmat(int shmid, char __user *shmaddr, int shmflg, ulong *raddr)
>  	sfd->vm_ops = NULL;
>  
>  	down_write(&current->mm->mmap_sem);
> -	if (addr && !(shmflg & SHM_REMAP)) {
> +	if (addr && !(shmflg & (SHM_REMAP|SHM_MAP_HINT))) {

I think you were right earlier that it can be just deleted, so why don't
you just do that?

-Andi

-- 
ak@linux.intel.com