* + mm-mglru-report-evictable-sizes-per-type.patch added to mm-new branch
@ 2026-11-14 22:10 Andrew Morton
0 siblings, 0 replies; 3+ messages in thread
From: Andrew Morton @ 2026-11-14 22:10 UTC (permalink / raw)
To: mm-commits, kasong, akpm
[-- Warning: decoded text below may be mangled, UTF-8 assumed --]
[-- Attachment #1: Type: text/plain, Size: 10964 bytes --]
The patch titled
Subject: mm/mglru: report evictable sizes per type
has been added to the -mm mm-new branch. Its filename is
mm-mglru-report-evictable-sizes-per-type.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-mglru-report-evictable-sizes-per-type.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
Before you just go and hit "reply", please:
a) Consider who else should be cc'ed
b) Prefer to cc a suitable mailing list as well
c) Ideally: find the original patch on the mailing list and do a
reply-to-all to that, adding suitable additional cc's
*** Remember to use Documentation/process/submit-checklist.rst when testing your code ***
The -mm tree is included into linux-next via various
branches at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
and is updated there most days
------------------------------------------------------
From: Kairui Song <kasong@tencent.com>
Subject: mm/mglru: report evictable sizes per type
Date: Sun, 15 Nov 2026 04:07:48 +0800
Patch series "mm: mglru: fix swappiness behavior", v9.
Classic LRU respects swappiness, while MGLRU only weakly honors it when
selecting the scan type. The fallback logic can easily override the bias
established by get_type_to_scan(). As a result, swappiness has a much
smaller overall impact when changing from 1 to 200, as shown by the data
presented later in this cover letter.
In this patchset, patches 1-8 from Kairui introduce a model that uses
refaults to determine nr_to_scan[] for both file and anon in MGLRU. For
each reclaim operation, we calculate how many file and anon folios to
scan, similar to CLRU, rather than relying on get_type_to_scan() and
fallback mechanisms to decide what to reclaim, which have proven rather
unreliable in honoring swappiness. This model also allows scanning and
reclaiming from the two youngest generations, including the youngest
generation itself. This can help resolve OOM situations[1] and reduce the
need for aging.
As Kairui mentioned, the OOM reproducer was demonstrated previously [2],
and that series was merged in v7 [3]. The problem was largely alleviated
as described, but not completely fixed. Under higher memory pressure, the
system could still hit OOM. Before this series, Kairui could still
reproduce OOM after hundreds of iterations. With the fixing patch in this
series applied, the problem no longer occurs.
Patch 9 from Barry fixes a cold/hot inversion exacerbated by patches 1–8
(which also exists in mainline) and improves reclaim efficiency.
Patches 10-15 from Gaofei and Barry optimize aging based on folio
distribution imbalance and improve reclaim behavior at extreme swappiness
values such as 1 and 200.
Patch 16 from Bo Zhang addresses the GFP_NOIO issue in MGLRU.
After the patchset, the results track CLRU across the full swappiness
range (see table below), with more file scanning at low swappiness and
more anon scanning at high swappiness.
pgsteal_file
swappiness CLRU MGLRU MGLRU+patches
1 6,620,680 745,968 6,197,601
36 807,807 508,974 564,256
71 553,144 417,700 420,008
106 402,880 402,474 363,635
141 240,293 337,797 312,624
176 187,682 330,045 238,722
200 0 343,949 0
pgsteal_anon
swappiness CLRU MGLRU MGLRU+patches
1 4,436,199 2,671,934 5,011,932
36 2,858,117 3,032,747 3,039,483
71 3,042,392 2,827,735 3,132,431
106 3,292,622 3,184,314 3,238,658
141 3,612,869 2,999,000 3,306,901
176 3,827,154 3,134,127 3,714,411
200 13,825,283 3,269,753 14,481,445
pgscan_file
swappiness CLRU MGLRU MGLRU+patches
1 11,853,625 877,311 13,108,154
36 1,016,826 582,783 657,973
71 662,823 474,772 457,686
106 496,374 451,285 390,056
141 277,109 382,604 329,819
176 206,261 372,059 246,141
200 0 393,608 0
pgscan_anon
swappiness CLRU MGLRU MGLRU+patches
1 20,804,386 5,847,747 6,936,021
36 17,830,330 6,740,075 5,975,744
71 18,357,293 6,126,194 6,797,243
106 19,938,920 6,431,355 7,602,990
141 19,609,579 5,997,762 8,540,965
176 21,612,749 6,071,032 10,532,510
200 44,776,474 6,544,125 30,296,434
refault_file
swappiness CLRU MGLRU MGLRU+patches
1 6,523,070 667,302 6,118,731
36 722,110 431,585 486,604
71 477,062 340,241 342,746
106 327,610 324,747 286,465
141 161,827 265,959 233,860
176 115,551 258,515 171,174
200 0 268,049 0
refault_anon
swappiness CLRU MGLRU MGLRU+patches
1 867,728 552,829 1,368,563
36 419,635 657,745 636,567
71 536,299 611,345 689,528
106 580,742 693,689 707,227
141 706,151 639,850 753,779
176 706,499 685,086 934,553
200 4,693,850 733,273 5,491,234
With a normal swappiness setting (without extreme bias), I see almost no
noticeable performance difference between the two versions.
For example, with `swappiness=60`, the average results
over 5 rounds are:
metric W/o patch W/ patch
real 1m49.273s 1m48.836s
user 25m33.186s 25m33.368s
sys 3m41.851s 3m38.388s
This patch (of 16):
Change lruvec_evictable_size() to return the number of evictable anonymous
and file pages separately instead of a single total, so that callers can
weigh the two types independently.
Update lruvec_is_sizable() and get_nr_to_scan() accordingly; the summed
totals are unchanged, so there is no functional change.
Link: https://lore.kernel.org/20261114200803.23129-1-baohua@kernel.org
Link: https://lore.kernel.org/20261114200803.23129-2-baohua@kernel.org
Link: https://github.com/ryncsn/emm-test-project/tree/master/file-anon-mix-pressure [1]
Link: https://lore.kernel.org/all/20260318-mglru-reclaim-v1-0-2c46f9eb0508@tencent.com/ [2]
Link: https://lore.kernel.org/linux-mm/20260428-mglru-reclaim-v7-0-02fabb92dc43@tencent.com/ [3]
Signed-off-by: Kairui Song <kasong@tencent.com>
Signed-off-by: Barry Song (Xiaomi) <baohua@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Kunwu Chan <kunwu.chan@gmail.com>
Reviewed-by: Baolin Wang <baolin.wang@linux.alibaba.com>
Cc: Axel Rasmussen <axelrasmussen@google.com>
Cc: Baoquan He <baoquan.he@linux.dev>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: <hui.zhu@linux.dev>
Cc: Liam R. Howlett <liam@infradead.org>
Cc: wang lian <lianux.mm@gmail.com>
Cc: <liuxiang.277@bytedance.com>
Cc: <lyugaofei@xiaomi.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Qi Zheng <qi.zheng@linux.dev>
Cc: Ridong Chen <ridong.chen@linux.dev>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Kairui Song <ryncsn@gmail.com>
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: Bo Zhang <zhangbo56@xiaomi.com>
Cc: Hui Zhu <zhuhui@kylinos.cn>
Cc: Siddharth Chintamaneni <sidchintamaneni@gmail.com>
Cc: Kunwu Chan <chentao@kylinos.cn>
Cc: Bo Zhang <zhangbo0325@gmail.com>
mm/vmscan.c | 22 +++++++++++++---------
1 file changed, 13 insertions(+), 9 deletions(-)
--- a/mm/vmscan.c~mm-mglru-report-evictable-sizes-per-type
+++ a/mm/vmscan.c
@@ -4193,28 +4193,31 @@ static void set_initial_priority(struct
sc->priority = clamp(priority, DEF_PRIORITY / 2, DEF_PRIORITY);
}
-static unsigned long lruvec_evictable_size(struct lruvec *lruvec, int swappiness)
+static void lruvec_evictable_size(struct lruvec *lruvec, int swappiness,
+ unsigned long nr[])
{
int type;
- unsigned long seq, total = 0;
+ unsigned long seq;
struct lru_gen_folio *lrugen = &lruvec->lrugen;
DEFINE_MAX_SEQ(lruvec);
DEFINE_MIN_SEQ(lruvec);
+ nr[LRU_GEN_ANON] = 0;
+ nr[LRU_GEN_FILE] = 0;
+
for_each_evictable_type(type, swappiness) {
for (seq = min_seq[type]; seq <= max_seq; seq++)
- total += lruvec_gen_size(lrugen, type, seq);
+ nr[type] += lruvec_gen_size(lrugen, type, seq);
}
-
- return total;
}
static bool lruvec_is_sizable(struct lruvec *lruvec, struct scan_control *sc)
{
- unsigned long total;
+ unsigned long total, sizes[ANON_AND_FILE];
int swappiness = get_swappiness(lruvec, sc);
- total = lruvec_evictable_size(lruvec, swappiness);
+ lruvec_evictable_size(lruvec, swappiness, sizes);
+ total = sizes[LRU_GEN_ANON] + sizes[LRU_GEN_FILE];
/* whether the size is big enough to be helpful */
return total >> sc->priority;
@@ -5028,7 +5031,7 @@ static bool should_run_aging(struct lruv
static long get_nr_to_scan(struct lruvec *lruvec, struct scan_control *sc,
struct mem_cgroup *memcg, int swappiness)
{
- unsigned long nr_to_scan, evictable;
+ unsigned long nr_to_scan, evictable, sizes[ANON_AND_FILE];
struct pglist_data *pgdat = lruvec_pgdat(lruvec);
/*
@@ -5044,7 +5047,8 @@ static long get_nr_to_scan(struct lruvec
return 0;
}
- evictable = lruvec_evictable_size(lruvec, swappiness);
+ lruvec_evictable_size(lruvec, swappiness, sizes);
+ evictable = sizes[LRU_GEN_ANON] + sizes[LRU_GEN_FILE];
nr_to_scan = apply_proportional_protection(memcg, sc, evictable);
nr_to_scan >>= sc->priority;
_
Patches currently in -mm which might be from kasong@tencent.com are
mm-mglru-report-evictable-sizes-per-type.patch
mm-mglru-extract-lruvec_populated_min_seq-helper.patch
mm-mglru-reclaim-from-the-oldest-populated-gen.patch
mm-mglru-lift-the-forced-protection-of-reclaimer.patch
mm-mglru-skip-zones-above-reclaim_idx-instead-of-rotating-them.patch
mm-mglru-return-for-unavailable-anon-reclaim-earlier.patch
mm-mglru-balance-anon-and-file-scan-budget-by-refault-rate.patch
mm-mglru-lift-youngest-gen-protection-for-higher-priority.patch
^ permalink raw reply [flat|nested] 3+ messages in thread* + mm-mglru-report-evictable-sizes-per-type.patch added to mm-new branch
@ 2026-11-13 19:50 Andrew Morton
0 siblings, 0 replies; 3+ messages in thread
From: Andrew Morton @ 2026-11-13 19:50 UTC (permalink / raw)
To: mm-commits, kasong, akpm
[-- Warning: decoded text below may be mangled, UTF-8 assumed --]
[-- Attachment #1: Type: text/plain, Size: 10963 bytes --]
The patch titled
Subject: mm/mglru: report evictable sizes per type
has been added to the -mm mm-new branch. Its filename is
mm-mglru-report-evictable-sizes-per-type.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-mglru-report-evictable-sizes-per-type.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
Before you just go and hit "reply", please:
a) Consider who else should be cc'ed
b) Prefer to cc a suitable mailing list as well
c) Ideally: find the original patch on the mailing list and do a
reply-to-all to that, adding suitable additional cc's
*** Remember to use Documentation/process/submit-checklist.rst when testing your code ***
The -mm tree is included into linux-next via various
branches at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
and is updated there most days
------------------------------------------------------
From: Kairui Song <kasong@tencent.com>
Subject: mm/mglru: report evictable sizes per type
Date: Sat, 14 Nov 2026 02:55:26 +0800
Patch series "mm: mglru: fix swappiness behavior", v8.
Classic LRU respects swappiness, while MGLRU only weakly honors it when
selecting the scan type. The fallback logic can easily override the bias
established by get_type_to_scan(). As a result, swappiness has a much
smaller overall impact when changing from 1 to 200, as shown by the data
presented later in this cover letter.
In this patchset, patches 1-8 from Kairui introduce a model that uses
refaults to determine nr_to_scan[] for both file and anon in MGLRU. For
each reclaim operation, we calculate how many file and anon folios to
scan, similar to CLRU, rather than relying on get_type_to_scan() and
fallback mechanisms to decide what to reclaim, which have proven rather
unreliable in honoring swappiness. This model also allows scanning and
reclaiming from the two youngest generations, including the youngest
generation itself. This can help resolve OOM situations[1] and reduce the
need for aging.
As Kairui mentioned, the OOM reproducer was demonstrated previously [2],
and that series was merged in v7 [3]. The problem was largely alleviated
as described, but not completely fixed. Under higher memory pressure, the
system could still hit OOM. Before this series, Kairui could still
reproduce OOM after hundreds of iterations. With the fixing patch in this
series applied, the problem no longer occurs.
Patch 9 from Barry fixes a cold/hot inversion exacerbated by patches
1–8 (which also exists in mainline) and improves reclaim efficiency.
Patches 10-15 from Gaofei and Barry optimize aging based on folio
distribution imbalance and improve reclaim behavior at extreme
swappiness values such as 1 and 200.
Patch 16 from Bo Zhang addresses the GFP_NOIO issue in MGLRU.
After the patchset, the results track CLRU across the full swappiness
range (see table below), with more file scanning at low swappiness
and more anon scanning at high swappiness.
pgsteal_file
swappiness CLRU MGLRU MGLRU+patches
1 6,620,680 745,968 6,190,575
36 807,807 508,974 525,304
71 553,144 417,700 405,545
106 402,880 402,474 348,365
141 240,293 337,797 305,170
176 187,682 330,045 231,038
200 0 343,949 256
pgsteal_anon
swappiness CLRU MGLRU MGLRU+patches
1 4,436,199 2,671,934 5,103,813
36 2,858,117 3,032,747 3,134,511
71 3,042,392 2,827,735 3,170,171
106 3,292,622 3,184,314 3,225,293
141 3,612,869 2,999,000 3,590,478
176 3,827,154 3,134,127 3,873,163
200 13,825,283 3,269,753 14,399,074
pgscan_file
swappiness CLRU MGLRU MGLRU+patches
1 11,853,625 877,311 12,715,103
36 1,016,826 582,783 612,867
71 662,823 474,772 443,149
106 496,374 451,285 364,203
141 277,109 382,604 327,444
176 206,261 372,059 236,838
200 0 393,608 256
pgscan_anon
swappiness CLRU MGLRU MGLRU+patches
1 20,804,386 5,847,747 7,142,640
36 17,830,330 6,740,075 6,297,912
71 18,357,293 6,126,194 7,046,149
106 19,938,920 6,431,355 7,876,121
141 19,609,579 5,997,762 9,672,762
176 21,612,749 6,071,032 11,195,357
200 44,776,474 6,544,125 30,225,030
refault_file
swappiness CLRU MGLRU MGLRU+patches
1 6,523,070 667,302 6,103,539
36 722,110 431,585 448,161
71 477,062 340,241 331,108
106 327,610 324,747 272,266
141 161,827 265,959 228,015
176 115,551 258,515 172,882
200 0 268,049 212
refault_anon
swappiness CLRU MGLRU MGLRU+patches
1 867,728 552,829 1,415,594
36 419,635 657,745 668,238
71 536,299 611,345 672,096
106 580,742 693,689 728,319
141 706,151 639,850 817,954
176 706,499 685,086 949,643
200 4,693,850 733,273 5,475,622
With a normal swappiness setting (without extreme bias), I see almost no
noticeable performance difference between the two versions.
For example, with `swappiness=60`, the average results
over 5 rounds are:
metric W/o patch W/ patch
real 1m49.273s 1m49.051s
user 25m33.186s 25m31.778s
sys 3m41.851s 3m40.721s
This patch (of 16):
Change lruvec_evictable_size() to return the number of evictable anonymous
and file pages separately instead of a single total, so that callers can
weigh the two types independently.
Update lruvec_is_sizable() and get_nr_to_scan() accordingly; the
summed totals are unchanged, so there is no functional change.
Link: https://lore.kernel.org/20261113185541.70203-1-baohua@kernel.org
Link: https://lore.kernel.org/20261113185541.70203-2-baohua@kernel.org
Link: https://github.com/ryncsn/emm-test-project/tree/master/file-anon-mix-pressure [1]
Link: https://lore.kernel.org/all/20260318-mglru-reclaim-v1-0-2c46f9eb0508@tencent.com/ [2]
Link: https://lore.kernel.org/linux-mm/20260428-mglru-reclaim-v7-0-02fabb92dc43@tencent.com/ [3]
Signed-off-by: Kairui Song <kasong@tencent.com>
Signed-off-by: Barry Song (Xiaomi) <baohua@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Kunwu Chan <kunwu.chan@gmail.com>
Reviewed-by: Baolin Wang <baolin.wang@linux.alibaba.com>
Cc: Axel Rasmussen <axelrasmussen@google.com>
Cc: Baoquan He <baoquan.he@linux.dev>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: <hui.zhu@linux.dev>
Cc: Liam R. Howlett <liam@infradead.org>
Cc: wang lian <lianux.mm@gmail.com>
Cc: <liuxiang.277@bytedance.com>
Cc: <lyugaofei@xiaomi.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Qi Zheng <qi.zheng@linux.dev>
Cc: Ridong Chen <ridong.chen@linux.dev>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Kairui Song <ryncsn@gmail.com>
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: Bo Zhang <zhangbo56@xiaomi.com>
Cc: Hui Zhu <zhuhui@kylinos.cn>
Cc: Siddharth Chintamaneni <sidchintamaneni@gmail.com>
Cc: Kunwu Chan <chentao@kylinos.cn>
Cc: Bo Zhang <zhangbo0325@gmail.com>
---
mm/vmscan.c | 22 +++++++++++++---------
1 file changed, 13 insertions(+), 9 deletions(-)
--- a/mm/vmscan.c~mm-mglru-report-evictable-sizes-per-type
+++ a/mm/vmscan.c
@@ -4193,28 +4193,31 @@ static void set_initial_priority(struct
sc->priority = clamp(priority, DEF_PRIORITY / 2, DEF_PRIORITY);
}
-static unsigned long lruvec_evictable_size(struct lruvec *lruvec, int swappiness)
+static void lruvec_evictable_size(struct lruvec *lruvec, int swappiness,
+ unsigned long nr[])
{
int type;
- unsigned long seq, total = 0;
+ unsigned long seq;
struct lru_gen_folio *lrugen = &lruvec->lrugen;
DEFINE_MAX_SEQ(lruvec);
DEFINE_MIN_SEQ(lruvec);
+ nr[LRU_GEN_ANON] = 0;
+ nr[LRU_GEN_FILE] = 0;
+
for_each_evictable_type(type, swappiness) {
for (seq = min_seq[type]; seq <= max_seq; seq++)
- total += lruvec_gen_size(lrugen, type, seq);
+ nr[type] += lruvec_gen_size(lrugen, type, seq);
}
-
- return total;
}
static bool lruvec_is_sizable(struct lruvec *lruvec, struct scan_control *sc)
{
- unsigned long total;
+ unsigned long total, sizes[ANON_AND_FILE];
int swappiness = get_swappiness(lruvec, sc);
- total = lruvec_evictable_size(lruvec, swappiness);
+ lruvec_evictable_size(lruvec, swappiness, sizes);
+ total = sizes[LRU_GEN_ANON] + sizes[LRU_GEN_FILE];
/* whether the size is big enough to be helpful */
return total >> sc->priority;
@@ -5028,7 +5031,7 @@ static bool should_run_aging(struct lruv
static long get_nr_to_scan(struct lruvec *lruvec, struct scan_control *sc,
struct mem_cgroup *memcg, int swappiness)
{
- unsigned long nr_to_scan, evictable;
+ unsigned long nr_to_scan, evictable, sizes[ANON_AND_FILE];
struct pglist_data *pgdat = lruvec_pgdat(lruvec);
/*
@@ -5044,7 +5047,8 @@ static long get_nr_to_scan(struct lruvec
return 0;
}
- evictable = lruvec_evictable_size(lruvec, swappiness);
+ lruvec_evictable_size(lruvec, swappiness, sizes);
+ evictable = sizes[LRU_GEN_ANON] + sizes[LRU_GEN_FILE];
nr_to_scan = apply_proportional_protection(memcg, sc, evictable);
nr_to_scan >>= sc->priority;
_
Patches currently in -mm which might be from kasong@tencent.com are
mm-mglru-report-evictable-sizes-per-type.patch
mm-mglru-extract-lruvec_populated_min_seq-helper.patch
mm-mglru-reclaim-from-the-oldest-populated-gen.patch
mm-mglru-lift-the-forced-protection-of-reclaimer.patch
mm-mglru-skip-zones-above-reclaim_idx-instead-of-rotating-them.patch
mm-mglru-return-for-unavailable-anon-reclaim-earlier.patch
mm-mglru-balance-anon-and-file-scan-budget-by-refault-rate.patch
mm-mglru-lift-youngest-gen-protection-for-higher-priority.patch
^ permalink raw reply [flat|nested] 3+ messages in thread* + mm-mglru-report-evictable-sizes-per-type.patch added to mm-new branch
@ 2026-11-12 1:17 Andrew Morton
0 siblings, 0 replies; 3+ messages in thread
From: Andrew Morton @ 2026-11-12 1:17 UTC (permalink / raw)
To: mm-commits, zhuhui, zhangbo56, yuanchu, weixugc, wangzicheng,
surenb, sidchintamaneni, shakeel.butt, ryncsn, rppt, ridong.chen,
qi.zheng, mhocko, lyugaofei, liuxiang.277, lianux.mm, liam,
kunwu.chan, hui.zhu, hannes, chentao, baoquan.he, baolin.wang,
baohua, axelrasmussen, kasong, akpm
[-- Warning: decoded text below may be mangled, UTF-8 assumed --]
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The patch titled
Subject: mm/mglru: report evictable sizes per type
has been added to the -mm mm-new branch. Its filename is
mm-mglru-report-evictable-sizes-per-type.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-mglru-report-evictable-sizes-per-type.patch
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git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
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------------------------------------------------------
From: Kairui Song <kasong@tencent.com>
Subject: mm/mglru: report evictable sizes per type
Date: Thu, 12 Nov 2026 07:25:48 +0800
Patch series "mm: mglru: fix swappiness behavior", v7.
Classic LRU respects swappiness, while MGLRU only weakly
honors it when selecting the scan type. The fallback logic
can easily override the bias established by
get_type_to_scan(). As a result, swappiness has a much
smaller overall impact when changing from 1 to 200, as
shown by the data presented later in this cover letter.
In this patchset, patches 1-8 from Kairui introduce a model that uses
refaults to determine nr_to_scan[] for both file and anon in MGLRU.
For each reclaim operation, we calculate how many file and anon
folios to scan, similar to CLRU, rather than relying on
get_type_to_scan() and fallback mechanisms to decide what to
reclaim, which have proven rather unreliable in honoring swappiness.
This model also allows scanning and reclaiming from the two youngest
generations, including the youngest generation itself. This can help
resolve OOM situations[1] and reduce the need for aging.
As Kairui mentioned, the OOM reproducer was demonstrated
previously [2], and that series was merged in v7 [3].
The problem was largely alleviated as described, but not
completely fixed. Under higher memory pressure, the system
could still hit OOM. Before this series, Kairui could still
reproduce OOM after hundreds of iterations. With the fixing
patch in this series applied, the problem no longer occurs.
Patch 9 from Barry fixes a cold/hot inversion exacerbated by patches
1–8 (which also exists in mainline) and improves reclaim efficiency.
Patches 10-15 from Gaofei and Barry optimize aging based on folio
distribution imbalance and improve reclaim behavior at extreme
swappiness values such as 1 and 200.
Patch 16 from Bo Zhang addresses the GFP_NOIO issue in MGLRU.
After the patchset, the results track CLRU across the full swappiness
range (see table below), with more file scanning at low swappiness
and more anon scanning at high swappiness.
pgsteal_file
swappiness CLRU MGLRU MGLRU+patches
1 6,620,680 745,968 6,249,276
36 807,807 508,974 569,354
71 553,144 417,700 419,718
106 402,880 402,474 329,145
141 240,293 337,797 296,131
176 187,682 330,045 260,850
200 0 343,949 128
pgsteal_anon
swappiness CLRU MGLRU MGLRU+patches
1 4,436,199 2,671,934 4,960,289
36 2,858,117 3,032,747 3,066,513
71 3,042,392 2,827,735 3,258,388
106 3,292,622 3,184,314 3,217,699
141 3,612,869 2,999,000 3,417,135
176 3,827,154 3,134,127 3,720,778
200 13,825,283 3,269,753 14,551,425
pgscan_file
swappiness CLRU MGLRU MGLRU+patches
1 11,853,625 877,311 13,703,243
36 1,016,826 582,783 680,534
71 662,823 474,772 467,822
106 496,374 451,285 356,494
141 277,109 382,604 307,866
176 206,261 372,059 268,584
200 0 393,608 128
pgscan_anon
swappiness CLRU MGLRU MGLRU+patches
1 20,804,386 5,847,747 6,766,764
36 17,830,330 6,740,075 5,870,434
71 18,357,293 6,126,194 7,333,437
106 19,938,920 6,431,355 7,702,863
141 19,609,579 5,997,762 8,915,973
176 21,612,749 6,071,032 10,590,224
200 44,776,474 6,544,125 30,318,894
refault_file
swappiness CLRU MGLRU MGLRU+patches
1 6,523,070 667,302 6,171,580
36 722,110 431,585 492,267
71 477,062 340,241 342,626
106 327,610 324,747 262,786
141 161,827 265,959 224,831
176 115,551 258,515 184,601
200 0 268,049 88
refault_anon
swappiness CLRU MGLRU MGLRU+patches
1 867,728 552,829 1,382,052
36 419,635 657,745 675,629
71 536,299 611,345 706,445
106 580,742 693,689 718,644
141 706,151 639,850 785,236
176 706,499 685,086 906,427
200 4,693,850 733,273 5,489,076
With a normal swappiness setting (without extreme bias), I
see almost no noticeable performance difference between
the two versions.
For example, with `swappiness=60`, the average results
over 5 rounds are:
metric W/o patch W/ patch
real 1m49.273s 1m48.876s
user 25m33.186s 25m31.449s
sys 3m41.851s 3m39.935s
This patch (of 16):
Change lruvec_evictable_size() to return the number of evictable
anonymous and file pages separately instead of a single total, so
that callers can weigh the two types independently.
Update lruvec_is_sizable() and get_nr_to_scan() accordingly; the
summed totals are unchanged, so there is no functional change.
Link: https://lore.kernel.org/20261111232603.9934-1-baohua@kernel.org
Link: https://lore.kernel.org/20261111232603.9934-2-baohua@kernel.org
Link: https://github.com/ryncsn/emm-test-project/tree/master/file-anon-mix-pressure [1]
Link: https://lore.kernel.org/all/20260318-mglru-reclaim-v1-0-2c46f9eb0508@tencent.com/ [2]
Link: https://lore.kernel.org/linux-mm/20260428-mglru-reclaim-v7-0-02fabb92dc43@tencent.com/ [3]
Signed-off-by: Kairui Song <kasong@tencent.com>
Signed-off-by: Barry Song (Xiaomi) <baohua@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Kunwu Chan <kunwu.chan@gmail.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: Liam R. Howlett <liam@infradead.org>
Cc: wang lian <lianux.mm@gmail.com>
Cc: <liuxiang.277@bytedance.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: Kairui Song <ryncsn@gmail.com>
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: Bo Zhang <zhangbo56@xiaomi.com>
Cc: Hui Zhu <zhuhui@kylinos.cn>
Cc: Siddharth Chintamaneni <sidchintamaneni@gmail.com>
Cc: Kunwu Chan <chentao@kylinos.cn>
---
mm/vmscan.c | 22 +++++++++++++---------
1 file changed, 13 insertions(+), 9 deletions(-)
--- a/mm/vmscan.c~mm-mglru-report-evictable-sizes-per-type
+++ a/mm/vmscan.c
@@ -4193,28 +4193,31 @@ static void set_initial_priority(struct
sc->priority = clamp(priority, DEF_PRIORITY / 2, DEF_PRIORITY);
}
-static unsigned long lruvec_evictable_size(struct lruvec *lruvec, int swappiness)
+static void lruvec_evictable_size(struct lruvec *lruvec, int swappiness,
+ unsigned long nr[])
{
int type;
- unsigned long seq, total = 0;
+ unsigned long seq;
struct lru_gen_folio *lrugen = &lruvec->lrugen;
DEFINE_MAX_SEQ(lruvec);
DEFINE_MIN_SEQ(lruvec);
+ nr[LRU_GEN_ANON] = 0;
+ nr[LRU_GEN_FILE] = 0;
+
for_each_evictable_type(type, swappiness) {
for (seq = min_seq[type]; seq <= max_seq; seq++)
- total += lruvec_gen_size(lrugen, type, seq);
+ nr[type] += lruvec_gen_size(lrugen, type, seq);
}
-
- return total;
}
static bool lruvec_is_sizable(struct lruvec *lruvec, struct scan_control *sc)
{
- unsigned long total;
+ unsigned long total, sizes[ANON_AND_FILE];
int swappiness = get_swappiness(lruvec, sc);
- total = lruvec_evictable_size(lruvec, swappiness);
+ lruvec_evictable_size(lruvec, swappiness, sizes);
+ total = sizes[LRU_GEN_ANON] + sizes[LRU_GEN_FILE];
/* whether the size is big enough to be helpful */
return total >> sc->priority;
@@ -5028,7 +5031,7 @@ static bool should_run_aging(struct lruv
static long get_nr_to_scan(struct lruvec *lruvec, struct scan_control *sc,
struct mem_cgroup *memcg, int swappiness)
{
- unsigned long nr_to_scan, evictable;
+ unsigned long nr_to_scan, evictable, sizes[ANON_AND_FILE];
struct pglist_data *pgdat = lruvec_pgdat(lruvec);
/*
@@ -5044,7 +5047,8 @@ static long get_nr_to_scan(struct lruvec
return 0;
}
- evictable = lruvec_evictable_size(lruvec, swappiness);
+ lruvec_evictable_size(lruvec, swappiness, sizes);
+ evictable = sizes[LRU_GEN_ANON] + sizes[LRU_GEN_FILE];
nr_to_scan = apply_proportional_protection(memcg, sc, evictable);
nr_to_scan >>= sc->priority;
_
Patches currently in -mm which might be from kasong@tencent.com are
mm-mglru-report-evictable-sizes-per-type.patch
mm-mglru-extract-lruvec_populated_min_seq-helper.patch
mm-mglru-reclaim-from-the-oldest-populated-gen.patch
mm-mglru-lift-the-forced-protection-of-reclaimer.patch
mm-mglru-skip-zones-above-reclaim_idx-instead-of-rotating-them.patch
mm-mglru-return-for-unavailable-anon-reclaim-earlier.patch
mm-mglru-balance-anon-and-file-scan-budget-by-refault-rate.patch
mm-mglru-lift-youngest-gen-protection-for-higher-priority.patch
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