+ mm-vmstat-avoid-taking-zone-lock-in-proc-buddyinfo-reads.patch added to mm-new branch

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

The patch titled
     Subject: mm/vmstat: avoid taking zone lock in /proc/buddyinfo reads
has been added to the -mm mm-new branch.  Its filename is
     mm-vmstat-avoid-taking-zone-lock-in-proc-buddyinfo-reads.patch

This patch will shortly appear at
     https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-vmstat-avoid-taking-zone-lock-in-proc-buddyinfo-reads.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

If a few days of testing in mm-new is successful, the patch will me moved
into mm.git's mm-unstable branch, which is included in linux-next

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------------------------------------------------------
From: Imran Khan <imran.f.khan@oracle.com>
Subject: mm/vmstat: avoid taking zone lock in /proc/buddyinfo reads
Date: Thu, 4 Jun 2026 21:42:45 +0800

frag_show_print() just reads zone->free_area[order].nr_free, so it can
safely do this without needing the zone->lock.

Pass nolock=true from frag_show(), so that walk_zones_in_node() can skip
the zone->lock acquisition.

Link: https://lore.kernel.org/20260604134245.1580287-1-imran.f.khan@oracle.com
Signed-off-by: Imran Khan <imran.f.khan@oracle.com>
Reviewed-by: Joshua Hahn <joshua.hahnjy@gmail.com>
Acked-by: Vlastimil Babka (SUSE) <vbabka@kernel.org>
Reviewed-by: Lorenzo Stoakes <ljs@kernel.org>
Acked-by: David Hildenbrand (Arm) <david@kernel.org>
Cc: Liam R. Howlett <liam@infradead.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

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

--- a/mm/vmstat.c~mm-vmstat-avoid-taking-zone-lock-in-proc-buddyinfo-reads
+++ a/mm/vmstat.c
@@ -1568,7 +1568,7 @@ static void frag_show_print(struct seq_f
 static int frag_show(struct seq_file *m, void *arg)
 {
 	pg_data_t *pgdat = (pg_data_t *)arg;
-	walk_zones_in_node(m, pgdat, true, false, frag_show_print);
+	walk_zones_in_node(m, pgdat, true, true, frag_show_print);
 	return 0;
 }
 
_

Patches currently in -mm which might be from imran.f.khan@oracle.com are

mm-vmstat-avoid-taking-zone-lock-in-proc-buddyinfo-reads.patch