Re: [PATCH v2 05/10] memory-failure: Remove raw_hwp_list_head()

[Usama Arif <usama.arif@linux.dev>]

On Thu,  9 Jul 2026 19:47:33 +0100 "Matthew Wilcox (Oracle)" <willy@infradead.org> wrote:

> There's no need to hide the llist_head; we can just declare it
> directly in struct folio and do away with raw_hwp_list_head().
> 
> Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
> ---
>  include/linux/mm_types.h |  4 ++--
>  mm/memory-failure.c      | 19 +++++--------------
>  2 files changed, 7 insertions(+), 16 deletions(-)
> 
> diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h
> index b18c2b2e7d2c..d46f81f94848 100644
> --- a/include/linux/mm_types.h
> +++ b/include/linux/mm_types.h
> @@ -387,7 +387,7 @@ typedef unsigned short mm_id_t;
>   * @_hugetlb_subpool: Do not use directly, use accessor in hugetlb.h.
>   * @_hugetlb_cgroup: Do not use directly, use accessor in hugetlb_cgroup.h.
>   * @_hugetlb_cgroup_rsvd: Do not use directly, use accessor in hugetlb_cgroup.h.
> - * @_hugetlb_hwpoison: Do not use directly, call raw_hwp_list_head().
> + * @_hugetlb_hwpoison: Raw error pages, see struct raw_hwp_page.

s/_hugetlb_hwpoison/hugetlb_hwpoison/ in the doc above, apart
from that, LGTM.

Also good to add No functional change intended in the commit message.

Acked-by: Usama Arif <usama.arif@linux.dev>

>   * @_deferred_list: Folios to be split under memory pressure.
>   * @_unused_slab_obj_exts: Placeholder to match obj_exts in struct slab.
>   *
> @@ -499,7 +499,7 @@ struct folio {
>  			void *_hugetlb_subpool;
>  			void *_hugetlb_cgroup;
>  			void *_hugetlb_cgroup_rsvd;
> -			void *_hugetlb_hwpoison;
> +			struct llist_head hugetlb_hwpoison;
>  	/* private: the union with struct page is transitional */
>  		};
>  		struct page __page_3;
> diff --git a/mm/memory-failure.c b/mm/memory-failure.c
> index 51508a55c405..53063e2a1f97 100644
> --- a/mm/memory-failure.c
> +++ b/mm/memory-failure.c
> @@ -1810,21 +1810,15 @@ EXPORT_SYMBOL_GPL(mf_dax_kill_procs);
>  
>  /*
>   * Struct raw_hwp_page represents information about "raw error page",
> - * constructing singly linked list from ->_hugetlb_hwpoison field of folio.
> + * constructing singly linked list from folio->hugetlb_hwpoison field.
>   */
>  struct raw_hwp_page {
>  	struct llist_node node;
>  	struct page *page;
>  };
>  
> -static inline struct llist_head *raw_hwp_list_head(struct folio *folio)
> -{
> -	return (struct llist_head *)&folio->_hugetlb_hwpoison;
> -}
> -
>  bool is_raw_hwpoison_page_in_hugepage(struct page *page)
>  {
> -	struct llist_head *raw_hwp_head;
>  	struct raw_hwp_page *p;
>  	struct folio *folio = page_folio(page);
>  	bool ret = false;
> @@ -1844,8 +1838,7 @@ bool is_raw_hwpoison_page_in_hugepage(struct page *page)
>  
>  	mutex_lock(&mf_mutex);
>  
> -	raw_hwp_head = raw_hwp_list_head(folio);
> -	llist_for_each_entry(p, raw_hwp_head->first, node) {
> +	llist_for_each_entry(p, folio->hugetlb_hwpoison.first, node) {
>  		if (page == p->page) {
>  			ret = true;
>  			break;
> @@ -1863,7 +1856,7 @@ static unsigned long __folio_free_raw_hwp(struct folio *folio, bool move_flag)
>  	struct raw_hwp_page *p, *next;
>  	unsigned long count = 0;
>  
> -	head = llist_del_all(raw_hwp_list_head(folio));
> +	head = llist_del_all(&folio->hugetlb_hwpoison);
>  	llist_for_each_entry_safe(p, next, head, node) {
>  		if (move_flag)
>  			SetPageHWPoison(p->page);
> @@ -1887,7 +1880,6 @@ static unsigned long __folio_free_raw_hwp(struct folio *folio, bool move_flag)
>   */
>  static int hugetlb_update_hwpoison(struct folio *folio, struct page *page)
>  {
> -	struct llist_head *head;
>  	struct raw_hwp_page *raw_hwp;
>  	struct raw_hwp_page *p;
>  	int ret = folio_test_set_hwpoison(folio) ? MF_HUGETLB_FOLIO_PRE_POISONED : 0;
> @@ -1899,8 +1891,7 @@ static int hugetlb_update_hwpoison(struct folio *folio, struct page *page)
>  	 */
>  	if (folio_test_hugetlb_raw_hwp_unreliable(folio))
>  		return MF_HUGETLB_FOLIO_PRE_POISONED;
> -	head = raw_hwp_list_head(folio);
> -	llist_for_each_entry(p, head->first, node) {
> +	llist_for_each_entry(p, folio->hugetlb_hwpoison.first, node) {
>  		if (p->page == page)
>  			return MF_HUGETLB_PAGE_PRE_POISONED;
>  	}
> @@ -1908,7 +1899,7 @@ static int hugetlb_update_hwpoison(struct folio *folio, struct page *page)
>  	raw_hwp = kmalloc_obj(struct raw_hwp_page, GFP_ATOMIC);
>  	if (raw_hwp) {
>  		raw_hwp->page = page;
> -		llist_add(&raw_hwp->node, head);
> +		llist_add(&raw_hwp->node, &folio->hugetlb_hwpoison);
>  	} else {
>  		/*
>  		 * Failed to save raw error info.  We no longer trace all
> -- 
> 2.47.3
> 
>