+ arm64-mte-pass-the-swap-entry-to-mte_save_tags.patch added to mm-new branch

[Andrew Morton <akpm@linux-foundation.org>]

The patch titled
     Subject: arm64: mte: pass the swap entry to mte_save_tags()
has been added to the -mm mm-new branch.  Its filename is
     arm64-mte-pass-the-swap-entry-to-mte_save_tags.patch

This patch will shortly appear at
     https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/arm64-mte-pass-the-swap-entry-to-mte_save_tags.patch

This patch will later appear in the mm-new branch at
    git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

Note, mm-new is a provisional staging ground for work-in-progress
patches, and acceptance into mm-new is a notification for others take
notice and to finish up reviews.  Please do not hesitate to respond to
review feedback and post updated versions to replace or incrementally
fixup patches in mm-new.

The mm-new branch of mm.git is not included in linux-next

If a few days of testing in mm-new is successful, the patch will me moved
into mm.git's mm-unstable branch, which is included in linux-next

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------------------------------------------------------
From: Tal Zussman <tz2294@columbia.edu>
Subject: arm64: mte: pass the swap entry to mte_save_tags()
Date: Tue, 08 Sep 2026 11:16:37 -0400

arch_prepare_to_swap() derives a page from the folio only for
mte_save_tags() to recompute the folio's swap entry from that page.  Pass
the entry in directly with folio_swap_entry(), matching
mte_restore_tags(), and move the page_mte_tagged() check into the caller
so we only compute the entry for tagged pages.

__mte_invalidate_tags() loses its only user, so remove it and call
mte_invalidate_tags() directly in the error path.  This removes two calls
to compound_head().

No functional change.

Link: https://lore.kernel.org/20260908-folio_swap_entry-v2-7-ee6d01dfa5e1@columbia.edu
Signed-off-by: Tal Zussman <tz2294@columbia.edu>
Cc: Baolin Wang <baolin.wang@linux.alibaba.com>
Cc: Baoquan He <baoquan.he@linux.dev>
Cc: Barry Song <baohua@kernel.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Chengming Zhou <chengming.zhou@linux.dev>
Cc: Chris Li <chrisl@kernel.org>
Cc: David Hildenbrand <david@kernel.org>
Cc: Dev Jain <dev.jain@arm.com>
Cc: Harry Yoo <harry@kernel.org>
Cc: Jann Horn <jannh@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Kairui Song <kasong@tencent.com>
Cc: Kemeng Shi <shikemeng@huaweicloud.com>
Cc: Kiryl Shutsemau <kas@kernel.org>
Cc: Lance Yang <lance.yang@linux.dev>
Cc: Liam R. Howlett <liam@infradead.org>
Cc: Lorenzo Stoakes <ljs@kernel.org>
Cc: Marc Rutland <mark.rutland@arm.com>
Cc: Nhat Pham <nphamcs@gmail.com>
Cc: Rik van Riel <riel@surriel.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Vlastimil Babka <vbabka@kernel.org>
Cc: Will Deacon <will@kernel.org>
Cc: Zi Yan <ziy@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 arch/arm64/mm/mteswap.c |   30 +++++++++++++-----------------
 1 file changed, 13 insertions(+), 17 deletions(-)

--- a/arch/arm64/mm/mteswap.c~arm64-mte-pass-the-swap-entry-to-mte_save_tags
+++ a/arch/arm64/mm/mteswap.c
@@ -20,22 +20,17 @@ void mte_free_tag_storage(char *storage)
 	kfree(storage);
 }
 
-static int mte_save_tags(struct page *page)
+static int mte_save_tags(swp_entry_t entry, struct page *page)
 {
 	void *tag_storage, *ret;
 
-	if (!page_mte_tagged(page))
-		return 0;
-
 	tag_storage = mte_allocate_tag_storage();
 	if (!tag_storage)
 		return -ENOMEM;
 
 	mte_save_page_tags(page_address(page), tag_storage);
 
-	/* lookup the swap entry.val from the page */
-	ret = xa_store(&mte_pages, page_swap_entry(page).val, tag_storage,
-		       GFP_KERNEL);
+	ret = xa_store(&mte_pages, entry.val, tag_storage, GFP_KERNEL);
 	if (WARN(xa_is_err(ret), "Failed to store MTE tags")) {
 		mte_free_tag_storage(tag_storage);
 		return xa_err(ret);
@@ -68,13 +63,6 @@ void mte_invalidate_tags(int type, pgoff
 	mte_free_tag_storage(tags);
 }
 
-static inline void __mte_invalidate_tags(struct page *page)
-{
-	swp_entry_t entry = page_swap_entry(page);
-
-	mte_invalidate_tags(swp_type(entry), swp_offset(entry));
-}
-
 void mte_invalidate_tags_area(int type)
 {
 	swp_entry_t entry = swp_entry(type, 0);
@@ -102,15 +90,23 @@ int arch_prepare_to_swap(struct folio *f
 	nr = folio_nr_pages(folio);
 
 	for (i = 0; i < nr; i++) {
-		err = mte_save_tags(folio_page(folio, i));
+		struct page *page = folio_page(folio, i);
+
+		if (!page_mte_tagged(page))
+			continue;
+
+		err = mte_save_tags(folio_swap_entry(folio, i), page);
 		if (err)
 			goto out;
 	}
 	return 0;
 
 out:
-	while (i--)
-		__mte_invalidate_tags(folio_page(folio, i));
+	while (i--) {
+		swp_entry_t swap = folio_swap_entry(folio, i);
+
+		mte_invalidate_tags(swp_type(swap), swp_offset(swap));
+	}
 	return err;
 }
 
_

Patches currently in -mm which might be from tz2294@columbia.edu are

mm-page_io-convert-write-completion-handlers-to-folios.patch
mm-remove-pagereclaim.patch
mm-page_io-use-swap-entries-directly-in-zeromap-helpers.patch
mm-page_io-rename-bio_associate_blkg_from_page.patch
mm-page_io-refer-to-folios-in-swap_writeout-comments.patch
mm-swap-rename-__swap_writepage-to-__swap_writeout.patch
mm-remove-unused-mark_page_reserved.patch
mm-remove-unused-totalram_pages_inc-and-totalram_pages_dec.patch
mm-remove-pagewriteback.patch
mm-swap-add-folio_swap_entry-and-folio_page_swap_entry.patch
mm-huge_memory-add-a-comment-to-the-open-coded-swap-entry.patch
mm-rmap-use-folio_page_swap_entry-in-ttu_anon_swapbacked_folio.patch
mm-zswap-use-folio_swap_entry-in-zswap_store_page.patch
mm-swapfile-use-folio_page_swap_entry.patch
arm64-mte-make-mte_save_tags-and-mte_restore_tags-static.patch
arm64-mte-pass-the-swap-entry-to-mte_save_tags.patch
mm-swap-remove-page_swap_entry.patch