Re: [PATCH v1 3/7] mm: rename and move page_is_poisoned()

On Thu 29-04-21 14:25:15, David Hildenbrand wrote:

Commit d3378e86d182 ("mm/gup: check page posion status for coredump.")
introduced page_is_poisoned(), however, v5 [1] of the patch used
"page_is_hwpoison()" and something went wrong while upstreaming. Rename the
function and move it to page-flags.h, from where it can be used in other
-- kcore -- context.

Move the comment to the place where it belongs and simplify.

[1] https://lkml.kernel.org/r/20210322193318.377c9ce9@alex-virtual-machine

Signed-off-by: David Hildenbrand <redacted>

I do agree that being explicit about hwpoison is much better. Poisoned
page can be also an unitialized one and I believe this is the reason why
you are bringing that up.

But you've made me look at d3378e86d182 and I am wondering whether this
is really a valid patch. First of all it can leak a reference count
AFAICS. Moreover it doesn't really fix anything because the page can be
marked hwpoison right after the check is done. I do not think the race
is feasible to be closed. So shouldn't we rather revert it?

-- 
Michal Hocko
SUSE Labs