Re: [PATCH v3 2/2] mm/memory-failure.c: make non-LRU movable pages unhandlable

[David Hildenbrand <david@redhat.com>]

On 18.03.22 08:39, Miaohe Lin wrote:
> We can not really handle non-LRU movable pages in memory failure. Typically
> they are balloon, zsmalloc, etc. Assuming we run into a base (4K) non-LRU
> movable page, we could reach as far as identify_page_state(), it should not
> fall into any category except me_unknown. For the non-LRU compound movable
> pages, they could be taken for transhuge pages but it's unexpected to split
> non-LRU  movable pages using split_huge_page_to_list in memory_failure. So
> we could just simply make non-LRU  movable pages unhandlable to avoid these
> possible nasty cases.
> 
> Suggested-by: Yang Shi <shy828301@gmail.com>
> Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
> Reviewed-by: Yang Shi <shy828301@gmail.com>
> Acked-by: Naoya Horiguchi <naoya.horiguchi@nec.com>
> ---
>  mm/memory-failure.c | 20 +++++++++++++-------
>  1 file changed, 13 insertions(+), 7 deletions(-)
> 
> diff --git a/mm/memory-failure.c b/mm/memory-failure.c
> index ecf45961f3b6..bf14bea2ed93 100644
> --- a/mm/memory-failure.c
> +++ b/mm/memory-failure.c
> @@ -1176,12 +1176,18 @@ void ClearPageHWPoisonTakenOff(struct page *page)
>   * does not return true for hugetlb or device memory pages, so it's assumed
>   * to be called only in the context where we never have such pages.
>   */
> -static inline bool HWPoisonHandlable(struct page *page)
> +static inline bool HWPoisonHandlable(struct page *page, unsigned long flags)
>  {
> -	return PageLRU(page) || __PageMovable(page) || is_free_buddy_page(page);
> +	bool movable = false;
> +
> +	/* Soft offline could mirgate non-LRU movable pages */

s/mirgate/migrate/

> +	if ((flags & MF_SOFT_OFFLINE) && __PageMovable(page))
> +		movable = true;

simply "return true" and drop "bool movable".

> +
> +	return movable || PageLRU(page) || is_free_buddy_page(page);

-- 
Thanks,

David / dhildenb