From: Zhongkun He Date: Mon, 21 Apr 2025 09:13:30 +0000 (+0800) Subject: mm: add max swappiness arg to lru_gen for anonymous memory only X-Git-Tag: v6.16-rc1~92^2~119 X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=b40599930f001b651cc3e1863e268dd35cbbf806;p=thirdparty%2Flinux.git mm: add max swappiness arg to lru_gen for anonymous memory only The MGLRU already supports reclaiming only from anonymous memory via the /sys/kernel/debug/lru_gen interface. Now, memory.reclaim also supports the swappiness=max parameter to enable reclaiming solely from anonymous memory. To unify the semantics of proactive reclaiming from anonymous folios, the max parameter is introduced. [hezhongkun.hzk@bytedance.com: use strcmp instead of strncmp, if swappiness is not set, use the default value] Link: https://lkml.kernel.org/r/20250507071057.3184240-1-hezhongkun.hzk@bytedance.com [akpm@linux-foundation.org: tweak coding style] Link: https://lkml.kernel.org/r/65181f7745d657d664d833c26d8a94cae40538b9.1745225696.git.hezhongkun.hzk@bytedance.com Signed-off-by: Zhongkun He Acked-by: Muchun Song Cc: Johannes Weiner Cc: Michal Hocko Cc: Yosry Ahmed Cc: Yu Zhao Signed-off-by: Andrew Morton --- diff --git a/Documentation/admin-guide/mm/multigen_lru.rst b/Documentation/admin-guide/mm/multigen_lru.rst index 33e068830497e..9cb54b4ff5d9d 100644 --- a/Documentation/admin-guide/mm/multigen_lru.rst +++ b/Documentation/admin-guide/mm/multigen_lru.rst @@ -151,8 +151,9 @@ generations less than or equal to ``min_gen_nr``. ``min_gen_nr`` should be less than ``max_gen_nr-1``, since ``max_gen_nr`` and ``max_gen_nr-1`` are not fully aged (equivalent to the active list) and therefore cannot be evicted. ``swappiness`` -overrides the default value in ``/proc/sys/vm/swappiness``. -``nr_to_reclaim`` limits the number of pages to evict. +overrides the default value in ``/proc/sys/vm/swappiness`` and the valid +range is [0-200, max], with max being exclusively used for the reclamation +of anonymous memory. ``nr_to_reclaim`` limits the number of pages to evict. A typical use case is that a job scheduler runs this command before it tries to land a new job on a server. If it fails to materialize enough diff --git a/mm/vmscan.c b/mm/vmscan.c index ca786575b6c2e..d1ad528186dd8 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -5588,24 +5588,35 @@ static ssize_t lru_gen_seq_write(struct file *file, const char __user *src, while ((cur = strsep(&next, ",;\n"))) { int n; int end; - char cmd; + char cmd, swap_string[5]; unsigned int memcg_id; unsigned int nid; unsigned long seq; - unsigned int swappiness = -1; + unsigned int swappiness; unsigned long opt = -1; cur = skip_spaces(cur); if (!*cur) continue; - n = sscanf(cur, "%c %u %u %lu %n %u %n %lu %n", &cmd, &memcg_id, &nid, - &seq, &end, &swappiness, &end, &opt, &end); + n = sscanf(cur, "%c %u %u %lu %n %4s %n %lu %n", &cmd, &memcg_id, &nid, + &seq, &end, swap_string, &end, &opt, &end); if (n < 4 || cur[end]) { err = -EINVAL; break; } + if (n == 4) { + swappiness = -1; + } else if (!strcmp("max", swap_string)) { + /* set by userspace for anonymous memory only */ + swappiness = SWAPPINESS_ANON_ONLY; + } else { + err = kstrtouint(swap_string, 0, &swappiness); + if (err) + break; + } + err = run_cmd(cmd, memcg_id, nid, seq, &sc, swappiness, opt); if (err) break;