Re: [PATCH] mm/gup: check page posion status for coredump.

[David Hildenbrand]

On 18.03.21 05:46, Matthew Wilcox wrote:
> On Wed, Mar 17, 2021 at 10:12:02AM +0100, David Hildenbrand wrote:
> > > +	if (IS_ENABLED(CONFIG_MEMORY_FAILURE) && ret == 1) {
> > > +		if (unlikely(PageHuge(page) && PageHWPoison(compound_head(page))))
> > > +			ret = 0;
> > > +		else if (unlikely(PageHWPoison(page)))
> > > +			ret = 0;
> > > +	}
> >
> > I wonder if a simple
> >
> > if (PageHWPoison(compound_head(page)))
> > 	ret = 0;
> >
> > won't suffice. But I guess the "issue" is compound pages that are not huge
> > pages or transparent huge pages.
>
> THPs don't set the HWPoison bit on the head page.
>
> https://lore.kernel.org/linux-mm/20210316140947.GA3420@xxxxxxxxxxxxxxxxxxxx/

Oh, okay -- I was missing that we actually already set the HWPoison bit 
before trying to split via TestSetPageHWPoison(). I thought for a second 
that if splitting fails, we don't set any HWPoison bit.

--
Thanks,

David / dhildenb