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FAILED: Patch "mm: multi-gen LRU: use {ptep,pmdp}_clear_young_notify()" failed to apply to v6.1-stable tree

PATCH Sasha Levin 1 participant 1 message Nov 6, 2024

Subsystems (6)
Stable branch Memory management MM core MGLRU +2 more subsystems
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Sasha Levin

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The patch below does not apply to the v6.1-stable tree.
If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <[email protected]>.

Thanks,
Sasha

------------------ original commit in Linus's tree ------------------

From 1d4832becdc2cdb2cffe2a6050c9d9fd8ff1c58c Mon Sep 17 00:00:00 2001
From: Yu Zhao <[email protected]>
Date: Sat, 19 Oct 2024 01:29:39 +0000
Subject: [PATCH] mm: multi-gen LRU: use {ptep,pmdp}_clear_young_notify()

When the MM_WALK capability is enabled, memory that is mostly accessed by a VM appears younger than it really is, therefore this memory will be less likely to be evicted. Therefore, the presence of a running VM can significantly increase swap-outs for non-VM memory, regressing the performance for the rest of the system.

Fix this regression by always calling {ptep,pmdp}_clear_young_notify() whenever we clear the young bits on PMDs/PTEs.

[[email protected]: fix link-time error]
Link https://lkml.kernel.org/r/[email protected] open here
Fixes bd74fdaea146 ("mm: multi-gen LRU: support page table walks")
Signed-off-by Yu Zhao <[email protected]>
Signed-off-by James Houghton <[email protected]>
Reported-by David Stevens <[email protected]>
Cc Axel Rasmussen <[email protected]>
Cc David Matlack <[email protected]>
Cc David Rientjes <[email protected]>
Cc Oliver Upton <[email protected]>
Cc Paolo Bonzini <[email protected]>
Cc Sean Christopherson <[email protected]>
Cc Wei Xu <[email protected]>
Cc <[email protected]>
Cc kernel test robot <[email protected]>
Signed-off-by Andrew Morton <[email protected]>
---
 include/linux/mmzone.h |  5 ++-
 mm/rmap.c              |  9 ++---
 mm/vmscan.c            | 88 +++++++++++++++++++++++-------------------
 3 files changed, 55 insertions(+), 47 deletions(-)
include/linux/mmzone.h +3 -2
index 9342e5692dab6..5b1c984daf454 100644
@@ -555,7 +555,7 @@ struct lru_gen_memcg {
 
 void lru_gen_init_pgdat(struct pglist_data *pgdat);
 void lru_gen_init_lruvec(struct lruvec *lruvec);
-void lru_gen_look_around(struct page_vma_mapped_walk *pvmw);
+bool lru_gen_look_around(struct page_vma_mapped_walk *pvmw);
 
 void lru_gen_init_memcg(struct mem_cgroup *memcg);
 void lru_gen_exit_memcg(struct mem_cgroup *memcg);

@@ -574,8 +574,9 @@ static inline void lru_gen_init_lruvec(struct lruvec *lruvec)
 {
 }
 
-static inline void lru_gen_look_around(struct page_vma_mapped_walk *pvmw)
+static inline bool lru_gen_look_around(struct page_vma_mapped_walk *pvmw)
 {
+	return false;
 }
 
 static inline void lru_gen_init_memcg(struct mem_cgroup *memcg)
mm/rmap.c +3 -6
index a8797d1b3d496..73d5998677d40 100644
@@ -885,13 +885,10 @@ static bool folio_referenced_one(struct folio *folio,
 			return false;
 		}
 
-		if (pvmw.pte) {
-			if (lru_gen_enabled() &&
-			    pte_young(ptep_get(pvmw.pte))) {
-				lru_gen_look_around(&pvmw);
+		if (lru_gen_enabled() && pvmw.pte) {
+			if (lru_gen_look_around(&pvmw))
 				referenced++;
-			}
-
+		} else if (pvmw.pte) {
 			if (ptep_clear_flush_young_notify(vma, address,
 						pvmw.pte))
 				referenced++;
mm/vmscan.c +49 -39

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