Re: [PATCH 1/2] mm/memory-failure.c: PageHuge is handled at the beginning of memory_failure

David Hildenbrand
2019-11-19T12:24:03Z

On 18.11.19 09:20, Wei Yang wrote:
> PageHuge is handled by memory_failure_hugetlb(), so this case could be
> removed.
>
> Signed-off-by: Wei Yang <richardw.yang@linux.intel.com>
> ---
> mm/memory-failure.c | 5 +----
> 1 file changed, 1 insertion(+), 4 deletions(-)
>
> diff --git a/mm/memory-failure.c b/mm/memory-failure.c
> index 3151c87dff73..392ac277b17d 100644
> --- a/mm/memory-failure.c
> +++ b/mm/memory-failure.c
> @@ -1359,10 +1359,7 @@ int memory_failure(unsigned long pfn, int flags)
> * page_remove_rmap() in try_to_unmap_one(). So to determine page status
> * correctly, we save a copy of the page flags at this time.
> */
> - if (PageHuge(p))
> - page_flags = hpage->flags;
> - else
> - page_flags = p->flags;
> + page_flags = p->flags;
>
> /*
> * unpoison always clear PG_hwpoison inside page lock
>

I somewhat miss a proper explanation why this is safe to do. We access
page flags here, so why is it safe to refer to the ones of the sub-page?

--

Thanks,

David / dhildenb