Re: [PATCH v2 1/5] mm/memory-failure: keep the folio, not the poisoned subpage, locked across split

[Kiryl Shutsemau <kas@kernel.org>]

On Tue, Jul 14, 2026 at 01:23:40PM +0100, Kiryl Shutsemau wrote:
> diff --git a/mm/memory-failure.c b/mm/memory-failure.c
> index 51508a55c405..68d42cbed458 100644
> --- a/mm/memory-failure.c
> +++ b/mm/memory-failure.c
> @@ -1657,11 +1657,18 @@ static int identify_page_state(unsigned long pfn, struct page *p,
>  static int try_to_split_thp_page(struct page *page, unsigned int new_order,
>  		bool release)
>  {
> +	struct folio *folio = page_folio(page);
>  	int ret;
>  
> -	lock_page(page);
> -	ret = split_huge_page_to_order(page, new_order);
> -	unlock_page(page);
> +	/*
> +	 * Lock and split at the head, not the poisoned subpage: __folio_split()
> +	 * keeps the anchor folio locked and needs it to stay in the page cache
> +	 * to pin the inode. A tail beyond EOF would be dropped yet returned
> +	 * locked, losing that pin. The caller re-locks @page afterwards.
> +	 */
> +	folio_lock(folio);
> +	ret = split_folio_to_order(folio, new_order);
> +	folio_unlock(folio);
>  
>  	if (ret && release)
>  		put_page(page);

Ughh.. This patch is broken, sorry.

Please ignore the patchset. Will follow up.

-- 
  Kiryl Shutsemau / Kirill A. Shutemov