+ mm-page_alloc-only-update-numa-min-ratios-on-sysctl-write.patch added to mm-unstable branch

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

The patch titled
     Subject: mm/page_alloc: only update NUMA min ratios on sysctl write
has been added to the -mm mm-unstable branch.  Its filename is
     mm-page_alloc-only-update-numa-min-ratios-on-sysctl-write.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-only-update-numa-min-ratios-on-sysctl-write.patch

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

Before you just go and hit "reply", please:
   a) Consider who else should be cc'ed
   b) Prefer to cc a suitable mailing list as well
   c) Ideally: find the original patch on the mailing list and do a
      reply-to-all to that, adding suitable additional cc's

*** Remember to use Documentation/process/submit-checklist.rst when testing your code ***

The -mm tree is included into linux-next via various
branches at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
and is updated there most days

------------------------------------------------------
From: Jianlin Shi <shijianlin11@foxmail.com>
Subject: mm/page_alloc: only update NUMA min ratios on sysctl write
Date: Thu, 4 Jun 2026 12:01:38 +0800

The sysctl handlers for min_unmapped_ratio and min_slab_ratio invoke
setup_min_unmapped_ratio() and setup_min_slab_ratio() unconditionally
after proc_dointvec_minmax(), even for read operations.

These setup functions first zero all per-NUMA node thresholds
(min_unmapped_pages and min_slab_pages) before recalculating them. 
Reading /proc sysctl entries therefore temporarily resets node reclaim
thresholds to zero, which may disturb the behavior of __node_reclaim() and
node_reclaim() during the recomputation.

Fix this by only calling the setup functions when the sysctl is actually
written (write == 1), matching the behavior of existing sysctl handlers
like min_free_kbytes and watermark_scale_factor.

This only affects systems with CONFIG_NUMA.

Link: https://lore.kernel.org/tencent_5891052AF9A4C2D490A62F478D446F74AB09@qq.com
Signed-off-by: Jianlin Shi <shijianlin11@foxmail.com>
Cc: Brendan Jackman <jackmanb@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Vlastimil Babka <vbabka@kernel.org>
Cc: Zi Yan <ziy@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 mm/page_alloc.c |    6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

--- a/mm/page_alloc.c~mm-page_alloc-only-update-numa-min-ratios-on-sysctl-write
+++ a/mm/page_alloc.c
@@ -6653,7 +6653,8 @@ static int sysctl_min_unmapped_ratio_sys
 	if (rc)
 		return rc;
 
-	setup_min_unmapped_ratio();
+	if (write)
+		setup_min_unmapped_ratio();
 
 	return 0;
 }
@@ -6680,7 +6681,8 @@ static int sysctl_min_slab_ratio_sysctl_
 	if (rc)
 		return rc;
 
-	setup_min_slab_ratio();
+	if (write)
+		setup_min_slab_ratio();
 
 	return 0;
 }
_

Patches currently in -mm which might be from shijianlin11@foxmail.com are

mm-page_alloc-only-update-numa-min-ratios-on-sysctl-write.patch