+ mm-mglru-avoid-scan-anon-while-swapcache-is-low-for-gfp_noio-allocation.patch added to mm-new branch

[Andrew Morton <akpm@linux-foundation.org>]

The patch titled
     Subject: mm/mglru: avoid scan anon while swapcache is low for GFP_NOIO allocation
has been added to the -mm mm-new branch.  Its filename is
     mm-mglru-avoid-scan-anon-while-swapcache-is-low-for-gfp_noio-allocation.patch

This patch will shortly appear at
     https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-mglru-avoid-scan-anon-while-swapcache-is-low-for-gfp_noio-allocation.patch

This patch will later appear in the mm-new branch at
    git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

Note, mm-new is a provisional staging ground for work-in-progress
patches, and acceptance into mm-new is a notification for others take
notice and to finish up reviews.  Please do not hesitate to respond to
review feedback and post updated versions to replace or incrementally
fixup patches in mm-new.

The mm-new branch of mm.git is not included in linux-next

If a few days of testing in mm-new is successful, the patch will me moved
into mm.git's mm-unstable branch, which is included in linux-next

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------------------------------------------------------
From: Bo Zhang <zhangbo56@xiaomi.com>
Subject: mm/mglru: avoid scan anon while swapcache is low for GFP_NOIO allocation
Date: Thu, 12 Nov 2026 07:26:03 +0800

With GFP_NOIO, we cannot reclaim anon folios unless they are in
the swap cache. CLRU skips anon reclaim when the swap cache is
very low by commit 74d9aa0d8e98 ("mm: vmscan: avoid anon scanning
for GFP_NOIO with low swapcache"). Apply the same logic to MGLRU.

The new scan-budget-based mechanism makes this straightforward to
implement. Thanks also to Xiang Liu, who previously attempted to fix
this before we had the scan-budget-based model [1].

Link: https://lore.kernel.org/20261111232603.9934-17-baohua@kernel.org
Link: https://lore.kernel.org/linux-mm/179248830836.1744016.8424217811286616919.noio-mglru-rfc-v2@bytedance.com/ [1]
Signed-off-by: Bo Zhang <zhangbo56@xiaomi.com>
Signed-off-by: Barry Song (Xiaomi) <baohua@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Co-developed-by: Barry Song (Xiaomi) <baohua@kernel.org>
Reviewed-by: Kunwu Chan <chentao@kylinos.cn>
Cc: Xiang Liu <liuxiang.277@bytedance.com>
Cc: Axel Rasmussen <axelrasmussen@google.com>
Cc: Baolin Wang <baolin.wang@linux.alibaba.com>
Cc: Baoquan He <baoquan.he@linux.dev>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: <hui.zhu@linux.dev>
Cc: Kairui Song <kasong@tencent.com>
Cc: Kunwu Chan <kunwu.chan@gmail.com>
Cc: Liam R. Howlett <liam@infradead.org>
Cc: wang lian <lianux.mm@gmail.com>
Cc: <lyugaofei@xiaomi.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Qi Zheng <qi.zheng@linux.dev>
Cc: Ridong Chen <ridong.chen@linux.dev>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Shakeel Butt <shakeel.butt@linux.dev>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: wangzicheng <wangzicheng@honor.com>
Cc: Wei Xu <weixugc@google.com>
Cc: Yuanchu Xie <yuanchu@google.com>
Cc: Hui Zhu <zhuhui@kylinos.cn>
Cc: Siddharth Chintamaneni <sidchintamaneni@gmail.com>
Cc: Bo Zhang <zhangbo0325@gmail.com>
---

 mm/vmscan.c |   27 ++++++++++-----------------
 1 file changed, 10 insertions(+), 17 deletions(-)

--- a/mm/vmscan.c~mm-mglru-avoid-scan-anon-while-swapcache-is-low-for-gfp_noio-allocation
+++ a/mm/vmscan.c
@@ -272,13 +272,6 @@ static inline bool reclaimable_anon_is_l
 	if (!sc || (sc->gfp_mask & __GFP_IO))
 		return false;
 
-	/*
-	 * FIXME: MGLRU doesn't fully respect can_reclaim_anon_pages() for the
-	 * scanning type, so only apply this to the traditional LRU for now.
-	 */
-	if (lru_gen_enabled())
-		return false;
-
 	if (memcg) {
 		struct lruvec *lruvec = mem_cgroup_lruvec(memcg, pgdat);
 
@@ -4213,6 +4206,8 @@ static void lruvec_evictable_size(struct
 	int type;
 	unsigned long seq;
 	struct lru_gen_folio *lrugen = &lruvec->lrugen;
+	struct mem_cgroup *memcg = lruvec_memcg(lruvec);
+	int nid = lruvec_pgdat(lruvec)->node_id;
 	DEFINE_MAX_SEQ(lruvec);
 	DEFINE_MIN_SEQ(lruvec);
 
@@ -4220,6 +4215,8 @@ static void lruvec_evictable_size(struct
 	nr[LRU_GEN_FILE] = 0;
 
 	for_each_evictable_type(type, swappiness) {
+		if (type == LRU_GEN_ANON && !can_reclaim_anon_pages(memcg, nid, sc))
+			continue;
 		for (seq = min_seq[type]; seq <= max_seq; seq++)
 			nr[type] += lruvec_gen_size(lrugen, type, seq, sc->reclaim_idx + 1);
 	}
@@ -4900,23 +4897,19 @@ static void lru_gen_balance_scan(struct
 {
 	struct lru_gen_folio *lrugen = &lruvec->lrugen;
 	u64 refault_rate[ANON_AND_FILE], anon_factor, file_factor;
-	u64 anon_scan, file_scan, total;
+	u64 anon_scan, file_scan;
 	u64 anon_weight, file_weight;
 	int size_bias;
 
-	total = nr[LRU_GEN_ANON] + nr[LRU_GEN_FILE];
-	if (!total)
-		return;
-
-	if (swappiness <= MIN_SWAPPINESS) {
+	if (swappiness <= MIN_SWAPPINESS)
 		nr[LRU_GEN_ANON] = 0;
-		nr[LRU_GEN_FILE] = min_t(u64, total_scan, nr[LRU_GEN_FILE]);
-		return;
-	}
 
-	if (swappiness == SWAPPINESS_ANON_ONLY) {
+	if (swappiness == SWAPPINESS_ANON_ONLY)
 		nr[LRU_GEN_FILE] = 0;
+
+	if (!nr[LRU_GEN_ANON] || !nr[LRU_GEN_FILE]) {
 		nr[LRU_GEN_ANON] = min_t(u64, total_scan, nr[LRU_GEN_ANON]);
+		nr[LRU_GEN_FILE] = min_t(u64, total_scan, nr[LRU_GEN_FILE]);
 		return;
 	}
 
_

Patches currently in -mm which might be from zhangbo56@xiaomi.com are

mm-mglru-avoid-scan-anon-while-swapcache-is-low-for-gfp_noio-allocation.patch