mm/mglru: update MG-LRU proactive reclaim statistics only to memcg

Users can use /sys/kernel/debug/lru_gen to trigger proactive memory
reclaim of a specified memcg.  Currently, statistics such as pgrefill,
pgscan and pgsteal will be updated to the /proc/vmstat system memory
statistics.

This will confuse some system memory pressure monitoring tools, making it
difficult to determine whether pgscan and pgsteal are caused by
system-level pressure or by proactive memory reclaim of some specific
memory cgroup.

Therefore, make this interface behave similarly to memory.reclaim.  Update
proactive memory reclaim statistics only to its memory cgroup.

Link: https://lkml.kernel.org/r/20250717082845.34673-1-jiahao.kernel@gmail.com
Signed-off-by: Hao Jia <jiahao1@lixiang.com>
Cc: Axel Rasmussen <axelrasmussen@google.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Greg Thelen <gthelen@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Kinsey Ho <kinseyho@google.com>
Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Qi Zheng <zhengqi.arch@bytedance.com>
Cc: Shakeel Butt <shakeel.butt@linux.dev>
Cc: Yuanchu Xie <yuanchu@google.com>
Cc: Yu Zhao <yuzhao@google.com>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Muchun Song <songmuchun@bytedance.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/mm/vmscan.c b/mm/vmscan.c
index a48aec8bfd9251f78526659bf4b924335b6c689a..b9a1cfeb2ddf2e314f75049b23affdf2765217eb 100644 (file)
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -5561,6 +5561,7 @@ static int run_cmd(char cmd, int memcg_id, int nid, unsigned long seq,
        if (memcg_id != mem_cgroup_id(memcg))
                goto done;
 
+       sc->target_mem_cgroup = memcg;
        lruvec = get_lruvec(memcg, nid);
 
        if (swappiness < MIN_SWAPPINESS)
@@ -5597,6 +5598,7 @@ static ssize_t lru_gen_seq_write(struct file *file, const char __user *src,
                .may_swap = true,
                .reclaim_idx = MAX_NR_ZONES - 1,
                .gfp_mask = GFP_KERNEL,
+               .proactive = true,
        };
 
        buf = kvmalloc(len + 1, GFP_KERNEL);