linux-kernel - [PATCH 5.18 760/879] mm, compaction: fast_find_migrateblock() should return pfn in the target zone

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Message-Id: <20220607165024.924465598@linuxfoundation.org>
Date:   Tue,  7 Jun 2022 19:04:38 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Rei Yamamoto <yamamoto.rei@...fujitsu.com>,
        Miaohe Lin <linmiaohe@...wei.com>,
        Mel Gorman <mgorman@...hsingularity.net>,
        Oscar Salvador <osalvador@...e.de>,
        Don Dutile <ddutile@...hat.com>,
        Wonhyuk Yang <vvghjk1234@...il.com>,
        Andrew Morton <akpm@...ux-foundation.org>
Subject: [PATCH 5.18 760/879] mm, compaction: fast_find_migrateblock() should return pfn in the target zone

From: Rei Yamamoto <yamamoto.rei@...fujitsu.com>

commit bbe832b9db2e1ad21522f8f0bf02775fff8a0e0e upstream.

At present, pages not in the target zone are added to cc->migratepages
list in isolate_migratepages_block().  As a result, pages may migrate
between nodes unintentionally.

This would be a serious problem for older kernels without commit
a984226f457f849e ("mm: memcontrol: remove the pgdata parameter of
mem_cgroup_page_lruvec"), because it can corrupt the lru list by
handling pages in list without holding proper lru_lock.

Avoid returning a pfn outside the target zone in the case that it is
not aligned with a pageblock boundary.  Otherwise
isolate_migratepages_block() will handle pages not in the target zone.

Link: https://lkml.kernel.org/r/20220511044300.4069-1-yamamoto.rei@jp.fujitsu.com
Fixes: 70b44595eafe ("mm, compaction: use free lists to quickly locate a migration source")
Signed-off-by: Rei Yamamoto <yamamoto.rei@...fujitsu.com>
Reviewed-by: Miaohe Lin <linmiaohe@...wei.com>
Acked-by: Mel Gorman <mgorman@...hsingularity.net>
Reviewed-by: Oscar Salvador <osalvador@...e.de>
Cc: Don Dutile <ddutile@...hat.com>
Cc: Wonhyuk Yang <vvghjk1234@...il.com>
Cc: Rei Yamamoto <yamamoto.rei@...fujitsu.com>
Cc: <stable@...r.kernel.org>
Signed-off-by: Andrew Morton <akpm@...ux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 mm/compaction.c |    2 ++
 1 file changed, 2 insertions(+)

--- a/mm/compaction.c
+++ b/mm/compaction.c
@@ -1858,6 +1858,8 @@ static unsigned long fast_find_migratebl
 
 				update_fast_start_pfn(cc, free_pfn);
 				pfn = pageblock_start_pfn(free_pfn);
+				if (pfn < cc->zone->zone_start_pfn)
+					pfn = cc->zone->zone_start_pfn;
 				cc->fast_search_fail = 0;
 				found_block = true;
 				set_pageblock_skip(freepage);