Re: [PATCH] ppc64: Fix possible race with set_pte on a present PTE

Andrea Arcangeli
2004-05-25T04:53:22Z

On Mon, May 24, 2004 at 09:43:00PM -0700, David Mosberger wrote:
> >>>>> On Tue, 25 May 2004 06:20:54 +0200, Andrea Arcangeli <andrea@suse.de> said:
>
> Andrea> the only architecture that has the accessed bit in
> Andrea> _hardware_ via page faults I know is ia64, but I don't know
> Andrea> if it has a mode to set it without page faults
>
> No, it doesn't.
>
> Andrea> and how it is implementing the accessed bit in linux.
>
> If the "accessed" or "dirty" bits are zero, accessing/writing the
> page will cause a fault which will be handled in a low-level
> fault handler. The Linux version of these handlers simply turn
> on the respective bit. See daccess_bit(), iaccess_bit(), and dirty_bit()
> in arch/ia64/kernel/ivt.S.

so you mean, this is being set in the arch section before ever reaching
handle_mm_fault? in such case my fix should work fine for ia64 too.

> Note: I'm on travel and haven't seen the context of this discussion
> and don't expect to have time to think about this until I return on
> Thursday. So if you don't hear from me, it's not because I'm ignoring
> you... ;-)

take your time ;) thanks a lot for the above hints about those ivt.S
functions (though I don't speak ia64 asm very well ;)