+ mm-page_alloc-fix-move_freepages_block-range-error.patch added to mm-unstable branch

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

The patch titled
     Subject: mm: page_alloc: fix move_freepages_block() range error
has been added to the -mm mm-unstable branch.  Its filename is
     mm-page_alloc-fix-move_freepages_block-range-error.patch

This patch will shortly appear at
     https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-page_alloc-fix-move_freepages_block-range-error.patch

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

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------------------------------------------------------
From: Johannes Weiner <hannes@cmpxchg.org>
Subject: mm: page_alloc: fix move_freepages_block() range error
Date: Mon, 11 Sep 2023 15:41:45 -0400

When a block is partially outside the zone of the cursor page, the
function cuts the range to the pivot page instead of the zone start.  This
can leave large parts of the block behind, which encourages incompatible
page mixing down the line (ask for one type, get another), and thus
long-term fragmentation.

This triggers reliably on the first block in the DMA zone, whose start_pfn
is 1.  The block is stolen, but everything before the pivot page (which
was often hundreds of pages) is left on the old list.

Link: https://lkml.kernel.org/r/20230911195023.247694-5-hannes@cmpxchg.org
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: Kefeng Wang <wangkefeng.wang@huawei.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Zi Yan <ziy@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 mm/page_alloc.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/mm/page_alloc.c~mm-page_alloc-fix-move_freepages_block-range-error
+++ a/mm/page_alloc.c
@@ -1646,7 +1646,7 @@ int move_freepages_block(struct zone *zo
 
 	/* Do not cross zone boundaries */
 	if (!zone_spans_pfn(zone, start_pfn))
-		start_pfn = pfn;
+		start_pfn = zone->zone_start_pfn;
 	if (!zone_spans_pfn(zone, end_pfn))
 		return 0;
 
_

Patches currently in -mm which might be from hannes@cmpxchg.org are

mm-page_alloc-fix-cma-and-highatomic-landing-on-the-wrong-buddy-list.patch
mm-page_alloc-remove-pcppage-migratetype-caching.patch
mm-page_alloc-fix-up-block-types-when-merging-compatible-blocks.patch
mm-page_alloc-move-free-pages-when-converting-block-during-isolation.patch
mm-page_alloc-fix-move_freepages_block-range-error.patch
mm-page_alloc-fix-freelist-movement-during-block-conversion.patch
mm-page_alloc-consolidate-free-page-accounting.patch