+ mm-swap-no-need-to-truncate-the-scan-border.patch added to mm-new branch

+ mm-swap-no-need-to-truncate-the-scan-border.patch added to mm-new branch

[Andrew Morton]

The patch titled
     Subject: mm, swap: no need to truncate the scan border
has been added to the -mm mm-new branch.  Its filename is
     mm-swap-no-need-to-truncate-the-scan-border.patch

This patch will shortly appear at
     https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-swap-no-need-to-truncate-the-scan-border.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

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------------------------------------------------------
From: Kairui Song <kasong@tencent.com>
Subject: mm, swap: no need to truncate the scan border
Date: Wed, 18 Feb 2026 04:06:35 +0800

swap_map had a static flexible size, so the last cluster won't be fully
covered, hence the allocator needs to check the scan border to avoid OOB. 
But the swap table has a fixed-sized swap table for each cluster, and the
slots beyond the device size are marked as bad slots.  The allocator can
simply scan all slots as usual, and any bad slots will be skipped.

Link: https://lkml.kernel.org/r/20260218-swap-table-p3-v3-10-f4e34be021a7@tencent.com
Signed-off-by: Kairui Song <kasong@tencent.com>
Acked-by: Chris Li <chrisl@kernel.org>
Cc: Baoquan He <bhe@redhat.com>
Cc: Barry Song <baohua@kernel.org>
Cc: David Hildenbrand <david@kernel.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Kairui Song <ryncsn@gmail.com>
Cc: Kemeng Shi <shikemeng@huaweicloud.com>
Cc: kernel test robot <lkp@intel.com>
Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: Nhat Pham <nphamcs@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 mm/swap.h     |    2 +-
 mm/swapfile.c |    2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

--- a/mm/swapfile.c~mm-swap-no-need-to-truncate-the-scan-border
+++ a/mm/swapfile.c
@@ -945,8 +945,8 @@ static unsigned int alloc_swap_scan_clus
 {
 	unsigned int next = SWAP_ENTRY_INVALID, found = SWAP_ENTRY_INVALID;
 	unsigned long start = ALIGN_DOWN(offset, SWAPFILE_CLUSTER);
-	unsigned long end = min(start + SWAPFILE_CLUSTER, si->max);
 	unsigned int order = likely(folio) ? folio_order(folio) : 0;
+	unsigned long end = start + SWAPFILE_CLUSTER;
 	unsigned int nr_pages = 1 << order;
 	bool need_reclaim, ret, usable;
 
--- a/mm/swap.h~mm-swap-no-need-to-truncate-the-scan-border
+++ a/mm/swap.h
@@ -85,7 +85,7 @@ static inline struct swap_cluster_info *
 		struct swap_info_struct *si, pgoff_t offset)
 {
 	VM_WARN_ON_ONCE(percpu_ref_is_zero(&si->users)); /* race with swapoff */
-	VM_WARN_ON_ONCE(offset >= si->max);
+	VM_WARN_ON_ONCE(offset >= roundup(si->max, SWAPFILE_CLUSTER));
 	return &si->cluster_info[offset / SWAPFILE_CLUSTER];
 }
 
_

Patches currently in -mm which might be from kasong@tencent.com are

mm-swap-speed-up-hibernation-allocation-and-writeout.patch
mm-swap-protect-si-swap_file-properly-and-use-as-a-mount-indicator.patch
mm-swap-clean-up-swapon-process-and-locking.patch
mm-swap-remove-redundant-arguments-and-locking-for-enabling-a-device.patch
mm-swap-consolidate-bad-slots-setup-and-make-it-more-robust.patch
mm-workingset-leave-highest-bits-empty-for-anon-shadow.patch
mm-swap-implement-helpers-for-reserving-data-in-the-swap-table.patch
mm-swap-mark-bad-slots-in-swap-table-directly.patch
mm-swap-simplify-swap-table-sanity-range-check.patch
mm-swap-use-the-swap-table-to-track-the-swap-count.patch
mm-swap-no-need-to-truncate-the-scan-border.patch
mm-swap-simplify-checking-if-a-folio-is-swapped.patch
mm-swap-no-need-to-clear-the-shadow-explicitly.patch