The patch titled
Subject: mm: page_alloc: defrag_mode kswapd/kcompactd watermarks fix
has been added to the -mm mm-unstable branch. Its filename is
mm-page_alloc-defrag_mode-kswapd-kcompactd-watermarks-fix.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-page_alloc-defrag_mode-kswapd-kcompactd-watermarks-fix.patch
This patch will later appear in the mm-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
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------------------------------------------------------
From: Johannes Weiner <hannes@xxxxxxxxxxx>
Subject: mm: page_alloc: defrag_mode kswapd/kcompactd watermarks fix
Date: Fri, 14 Mar 2025 11:38:41 -0400
Fix squawks from rebasing that affect the behavior of !defrag_mode.
FWIW, it seems to actually have slightly helped the vanilla kernel in
the benchmark. But the point was to not change the default behavior:
VANILLA WMARKFIX-VANILLA
Hugealloc Time mean 52739.45 ( +0.00%) 62758.21 ( +19.00%)
Hugealloc Time stddev 56541.26 ( +0.00%) 76253.41 ( +34.86%)
Kbuild Real time 197.47 ( +0.00%) 197.25 ( -0.11%)
Kbuild User time 1240.49 ( +0.00%) 1241.33 ( +0.07%)
Kbuild System time 70.08 ( +0.00%) 71.00 ( +1.28%)
THP fault alloc 46727.07 ( +0.00%) 41492.73 ( -11.20%)
THP fault fallback 21910.60 ( +0.00%) 27146.53 ( +23.90%)
Direct compact fail 195.80 ( +0.00%) 260.93 ( +33.10%)
Direct compact success 7.93 ( +0.00%) 6.67 ( -14.18%)
Direct compact success rate % 3.51 ( +0.00%) 2.76 ( -16.78%)
Compact daemon scanned migrate 3369601.27 ( +0.00%) 3827734.27 ( +13.60%)
Compact daemon scanned free 5075474.47 ( +0.00%) 5910839.73 ( +16.46%)
Compact direct scanned migrate 161787.27 ( +0.00%) 168271.13 ( +4.01%)
Compact direct scanned free 163467.53 ( +0.00%) 222558.33 ( +36.15%)
Compact total migrate scanned 3531388.53 ( +0.00%) 3996005.40 ( +13.16%)
Compact total free scanned 5238942.00 ( +0.00%) 6133398.07 ( +17.07%)
Alloc stall 2371.07 ( +0.00%) 2478.00 ( +4.51%)
Pages kswapd scanned 2160926.73 ( +0.00%) 1726204.67 ( -20.12%)
Pages kswapd reclaimed 533191.07 ( +0.00%) 537963.73 ( +0.90%)
Pages direct scanned 400450.33 ( +0.00%) 450004.87 ( +12.37%)
Pages direct reclaimed 94441.73 ( +0.00%) 99193.07 ( +5.03%)
Pages total scanned 2561377.07 ( +0.00%) 2176209.53 ( -15.04%)
Pages total reclaimed 627632.80 ( +0.00%) 637156.80 ( +1.52%)
Swap out 47959.53 ( +0.00%) 45186.20 ( -5.78%)
Swap in 7276.00 ( +0.00%) 7109.40 ( -2.29%)
File refaults 138043.00 ( +0.00%) 145238.73 ( +5.21%)
Link: https://lkml.kernel.org/r/20250314210558.GD1316033@xxxxxxxxxxx
Signed-off-by: Johannes Weiner <hannes@xxxxxxxxxxx>
Cc: Mel Gorman <mgorman@xxxxxxxxxxxxxxxxxxx>
Cc: Vlastimil Babka <vbabka@xxxxxxx>
Cc: Zi Yan <ziy@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/compaction.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)
--- a/mm/compaction.c~mm-page_alloc-defrag_mode-kswapd-kcompactd-watermarks-fix
+++ a/mm/compaction.c
@@ -3075,6 +3075,8 @@ static bool kcompactd_node_suitable(pg_d
struct zone *zone;
enum zone_type highest_zoneidx = pgdat->kcompactd_highest_zoneidx;
enum compact_result ret;
+ unsigned int alloc_flags = defrag_mode ?
+ ALLOC_WMARK_HIGH : ALLOC_WMARK_MIN;
for (zoneid = 0; zoneid <= highest_zoneidx; zoneid++) {
zone = &pgdat->node_zones[zoneid];
@@ -3084,7 +3086,7 @@ static bool kcompactd_node_suitable(pg_d
ret = compaction_suit_allocation_order(zone,
pgdat->kcompactd_max_order,
- highest_zoneidx, ALLOC_WMARK_MIN,
+ highest_zoneidx, alloc_flags,
false, true);
if (ret == COMPACT_CONTINUE)
return true;
@@ -3108,7 +3110,7 @@ static void kcompactd_do_work(pg_data_t
.mode = MIGRATE_SYNC_LIGHT,
.ignore_skip_hint = false,
.gfp_mask = GFP_KERNEL,
- .alloc_flags = ALLOC_WMARK_HIGH,
+ .alloc_flags = defrag_mode ? ALLOC_WMARK_HIGH : ALLOC_WMARK_MIN,
};
enum compact_result ret;
_
Patches currently in -mm which might be from hannes@xxxxxxxxxxx are
mm-memcontrol-unshare-v2-only-charge-api-bits-again.patch
mm-memcontrol-move-stray-ratelimit-bits-to-v1.patch
mm-memcontrol-move-memsw-charge-callbacks-to-v1.patch
mm-page_alloc-dont-steal-single-pages-from-biggest-buddy.patch
mm-page_alloc-remove-remnants-of-unlocked-migratetype-updates.patch
mm-page_alloc-group-fallback-functions-together.patch
mm-swap_cgroup-remove-double-initialization-of-locals.patch
mm-compaction-push-watermark-into-compaction_suitable-callers.patch
mm-page_alloc-trace-type-pollution-from-compaction-capturing.patch
mm-page_alloc-defrag_mode.patch
mm-page_alloc-defrag_mode-kswapd-kcompactd-assistance.patch
mm-page_alloc-defrag_mode-kswapd-kcompactd-watermarks.patch
mm-page_alloc-defrag_mode-kswapd-kcompactd-watermarks-fix.patch
