Re: [PATCH] [6/16] HWPOISON: Add various poison checks in mm/memory.c

Nick Piggin
2009-06-09T10:39:29Z

On Wed, Jun 03, 2009 at 08:46:38PM +0200, Andi Kleen wrote:
>
> Bail out early when hardware poisoned pages are found in page fault handling.
> Since they are poisoned they should not be mapped freshly into processes,
> because that would cause another (potentially deadly) machine check
>
> This is generally handled in the same way as OOM, just a different
> error code is returned to the architecture code.
>
> Signed-off-by: Andi Kleen <ak@linux.intel.com>
>
> ---
> mm/memory.c | 3 +++
> 1 file changed, 3 insertions(+)
>
> Index: linux/mm/memory.c
> ===================================================================
> --- linux.orig/mm/memory.c 2009-06-03 19:36:23.000000000 +0200
> +++ linux/mm/memory.c 2009-06-03 19:36:23.000000000 +0200
> @@ -2797,6 +2797,9 @@
> if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE)))
> return ret;
>
> + if (unlikely(PageHWPoison(vmf.page)))
> + return VM_FAULT_HWPOISON;

Again, it would be nice if you just worry about this in your MCE
handler and don't sprinkle things like this in fastpaths.

> +
> /*
> * For consistency in subsequent calls, make the faulted page always
> * locked.