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 674999999cd067abc1481bd4c25ec3d66aeb30cc..4025e614e59e4e82d1e36765f0fb2fc1c4220baa 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);