+ mm-page_alloc-avoid-false-page-outside-zone-error-info.patch added to mm-unstable branch

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

The patch titled
     Subject: mm: page_alloc: avoid false page outside zone error info
has been added to the -mm mm-unstable branch.  Its filename is
     mm-page_alloc-avoid-false-page-outside-zone-error-info.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-avoid-false-page-outside-zone-error-info.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: Miaohe Lin <linmiaohe@huawei.com>
Subject: mm: page_alloc: avoid false page outside zone error info
Date: Tue, 4 Jul 2023 19:18:23 +0800

If pfn is outside zone boundaries in the first round, ret will be set to
1.  But if pfn is changed to inside the zone boundaries in zone span
seqretry path, ret is still set to 1 leading to false page outside zone
error info.

This is from code inspection.  The race window should be really small thus
hard to trigger in real world.

Link: https://lkml.kernel.org/r/20230704111823.940331-1-linmiaohe@huawei.com
Fixes: bdc8cb984576 ("[PATCH] memory hotplug locking: zone span seqlock")
Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
Cc: Matthew Wilcox <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 mm/page_alloc.c |    4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

--- a/mm/page_alloc.c~mm-page_alloc-avoid-false-page-outside-zone-error-info
+++ a/mm/page_alloc.c
@@ -459,7 +459,7 @@ void set_pageblock_migratetype(struct pa
 #ifdef CONFIG_DEBUG_VM
 static int page_outside_zone_boundaries(struct zone *zone, struct page *page)
 {
-	int ret = 0;
+	int ret;
 	unsigned seq;
 	unsigned long pfn = page_to_pfn(page);
 	unsigned long sp, start_pfn;
@@ -470,6 +470,8 @@ static int page_outside_zone_boundaries(
 		sp = zone->spanned_pages;
 		if (!zone_spans_pfn(zone, pfn))
 			ret = 1;
+		else
+			ret = 0;
 	} while (zone_span_seqretry(zone, seq));
 
 	if (ret)
_

Patches currently in -mm which might be from linmiaohe@huawei.com are

mm-mm_initc-update-obsolete-comment-in-get_pfn_range_for_nid.patch
mm-memory-failure-fix-unexpected-return-value-in-soft_offline_page.patch
mm-memory-failure-fix-potential-page-refcnt-leak-in-memory_failure.patch
mm-memory-failure-remove-unneeded-page-state-check-in-shake_page.patch
memory-tier-use-helper-function-destroy_memory_type.patch
mm-memory-failure-remove-unneeded-inline-annotation.patch
mm-mm_initc-remove-obsolete-macro-hash_small.patch
mm-page_alloc-avoid-false-page-outside-zone-error-info.patch