mm/vmscan: when the swappiness is set to 0, memory swapping should be prohibited during the global reclaim process

Commit Message

ying chen Feb. 27, 2025, 7:51 a.m. UTC

From 512ea4430805983e949526cce2179d0c37f54450 Mon Sep 17 00:00:00 2001
From: yc1082463 <[e-mail]>
Date: Thu, 27 Feb 2025 15:28:28 +0800
Subject: [PATCH] mm/vmscan: when the swappiness is set to 0, memory swapping
 should be prohibited during the global reclaim process.

When we use zram as swap disks, global reclaim may cause the memory in some
cgroups with memory.swappiness set to 0 to be swapped into zram. This memory
won't be swapped back immediately after the free memory increases. Instead,
it will continue to occupy the zram space, which may result in no available
zram space for the cgroups with swapping enabled. Therefore, I think that
when the vm.swappiness is set to 0, global reclaim should also refrain
from memory swapping, just like these cgroups.

Signed-off-by: yc1082463 <[e-mail]>
---
 mm/vmscan.c | 9 +--------
 1 file changed, 1 insertion(+), 8 deletions(-)

        }
--
2.34.1

Patch

diff --git a/mm/vmscan.c b/mm/vmscan.c
index c767d71c43d7..bdbb0fc03412 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -2426,14 +2426,7 @@  static void get_scan_count(struct lruvec *lruvec,
struct scan_control *sc,
                goto out;
        }

-       /*
-        * Global reclaim will swap to prevent OOM even with no
-        * swappiness, but memcg users want to use this knob to
-        * disable swapping for individual groups completely when
-        * using the memory controller's swap limit feature would be
-        * too expensive.
-        */
-       if (cgroup_reclaim(sc) && !swappiness) {
+       if (!swappiness) {
                scan_balance = SCAN_FILE;
                goto out;