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 7de11524a9369a31f4076047b164e725b430eee4..a4bc894483b1bda51ae536e743c9fa9d2363ecf1 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);