Re: [PATCH] HWPOISON: Implement hwpoison-on-free for soft offlining

[Andi Kleen]

 On 10/12/2010 2:26 PM, Wu Fengguang wrote:
> > +#if defined(CONFIG_MEMORY_FAILURE)&&  BITS_PER_LONG == 64
> We have the simpler CONFIG_HWPOISON_ON_FREE :)

Leftover from when I didn't have that. Fixed.

> > +PAGEFLAG(HWPoisonOnFree, hwpoison_on_free)
> > +TESTSCFLAG(HWPoisonOnFree, hwpoison_on_free)
> > +#define __PG_HWPOISON_ON_FREE (1UL<<  PG_hwpoison_on_free)
> > +#else
> > +PAGEFLAG_FALSE(HWPoisonOnFree)
> Could define SETPAGEFLAG_NOOP(HWPoisonOnFree) too, for eliminating an
> #ifdef in the .c file.

Ok.

> >   	}
> > +
> > +	if (PageHWPoisonOnFree(page)) {
> > +		pr_info("soft_offline: %#lx: Delaying poision of unknown page %lx to free\n",
> > +			pfn, page->flags);
> > +		return -EIO; /* or 0? */
> -EIO looks safer because HWPoisonOnFree does not guarantee success.
Ok.

> > diff --git a/mm/page_alloc.c b/mm/page_alloc.c
> > index a8cfa9c..519c24c 100644
> > --- a/mm/page_alloc.c
> > +++ b/mm/page_alloc.c
> > @@ -564,6 +564,8 @@ static inline int free_pages_check(struct page *page)
> >   		(page->mapping != NULL)  |
> >   		(atomic_read(&page->_count) != 0) |
> >   		(page->flags&  PAGE_FLAGS_CHECK_AT_FREE))) {
> > +		if (PageHWPoisonOnFree(page))
> > +			hwpoison_page_on_free(page);
> hwpoison_page_on_free() seems to be undefined when
> CONFIG_HWPOISON_ON_FREE is not defined.

Yes, but I rely on the compiler never generating the call in this case 
because
the test is zero.

It would fail on a unoptimized build, but the kernel doesn't support 
that anyways.

Thanks for the review.

-Andi

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/