FAILED: patch "[PATCH] mm: multi-gen LRU: use {ptep,pmdp}_clear_young_notify()" failed to apply to 6.6-stable tree

The patch below does not apply to the 6.6-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]>.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.6.y
git checkout FETCH_HEAD
git cherry-pick -x 1d4832becdc2cdb2cffe2a6050c9d9fd8ff1c58c
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<[email protected]>' --in-reply-to '2024110509-doable-blemish-19d2@gregkh' --subject-prefix 'PATCH 6.6.y' HEAD^..

Possible dependencies:

thanks,

greg k-h

------------------ 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.

index 9342e5692dab..5b1c984daf45 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)

index a8797d1b3d49..73d5998677d4 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++;