+ mm-vmstat-annotate-data-race-for-zone-free_areanr_free-fix.patch added to -mm tree

+ mm-vmstat-annotate-data-race-for-zone-free_areanr_free-fix.patch added to -mm tree

[akpm]

The patch titled
     Subject: mm-vmstat-annotate-data-race-for-zone-free_areanr_free-fix
has been added to the -mm tree.  Its filename is
     mm-vmstat-annotate-data-race-for-zone-free_areanr_free-fix.patch

This patch should soon appear at
    https://ozlabs.org/~akpm/mmots/broken-out/mm-vmstat-annotate-data-race-for-zone-free_areanr_free-fix.patch
and later at
    https://ozlabs.org/~akpm/mmotm/broken-out/mm-vmstat-annotate-data-race-for-zone-free_areanr_free-fix.patch

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------------------------------------------------------
From: Liu Shixin <liushixin2@huawei.com>
Subject: mm-vmstat-annotate-data-race-for-zone-free_areanr_free-fix

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Link: https://lkml.kernel.org/r/20210918084655.2696522-1-liushixin2@huawei.com
Signed-off-by: Liu Shixin <liushixin2@huawei.com>
Cc: "Paul E . McKenney" <paulmck@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 mm/vmstat.c |   11 ++++++++++-
 1 file changed, 10 insertions(+), 1 deletion(-)

--- a/mm/vmstat.c~mm-vmstat-annotate-data-race-for-zone-free_areanr_free-fix
+++ a/mm/vmstat.c
@@ -1070,7 +1070,12 @@ static void fill_contig_page_info(struct
 	for (order = 0; order < MAX_ORDER; order++) {
 		unsigned long blocks;
 
-		/* Count number of free blocks */
+		/*
+		 * Count number of free blocks.
+		 *
+		 * Access to nr_free is lockless as nr_free is used only for
+		 * diagnostic purposes. Use data_race to avoid KCSAN warning.
+		 */
 		blocks = data_race(zone->free_area[order].nr_free);
 		info->free_blocks_total += blocks;
 
@@ -1445,6 +1450,10 @@ static void frag_show_print(struct seq_f
 
 	seq_printf(m, "Node %d, zone %8s ", pgdat->node_id, zone->name);
 	for (order = 0; order < MAX_ORDER; ++order)
+		/*
+		 * Access to nr_free is lockless as nr_free is used only for
+		 * printing purposes. Use data_race to avoid KCSAN warning.
+		 */
 		seq_printf(m, "%6lu ", data_race(zone->free_area[order].nr_free));
 	seq_putc(m, '\n');
 }
_

Patches currently in -mm which might be from liushixin2@huawei.com are

mm-vmstat-annotate-data-race-for-zone-free_areanr_free.patch
mm-vmstat-annotate-data-race-for-zone-free_areanr_free-fix.patch