[PATCH v3 2/2] mm: memcg: reset oom_group in css_reset

[Jiayuan Chen]

From: Jiayuan Chen <jiayuan.chen@xxxxxxxxxx>

memory.oom.group defaults to disabled, but css_reset did not clear
memcg->oom_group when a disabled memory css is kept alive by another
controller dependency.

Reset it with the other memory controller policies so a hidden memcg
cannot keep applying stale group OOM kill policy.

Cc: Jiayuan Chen <jiayuan.chen@xxxxxxxxx>
Signed-off-by: Jiayuan Chen <jiayuan.chen@xxxxxxxxxx>
---
It is found when Sashiko reviewed my previous patch.
https://sashiko.dev/#/patchset/20260702024827.353185-1-jiayuan.chen%40linux.dev
---
 mm/memcontrol.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index c20ef3c1d6fe..c7de62c8f86f 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -4362,6 +4362,7 @@ static void mem_cgroup_css_reset(struct cgroup_subsys_state *css)
 
 	page_counter_set_max(&memcg->memory, PAGE_COUNTER_MAX);
 	page_counter_set_max(&memcg->swap, PAGE_COUNTER_MAX);
+	WRITE_ONCE(memcg->oom_group, false);
 #ifdef CONFIG_ZSWAP
 	WRITE_ONCE(memcg->zswap_max, PAGE_COUNTER_MAX);
 	WRITE_ONCE(memcg->zswap_writeback, true);
-- 
2.43.0