+ mm-mglru-clean-up-workingset.patch added to mm-unstable branch

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

The patch titled
     Subject: mm/mglru: clean up workingset
has been added to the -mm mm-unstable branch.  Its filename is
     mm-mglru-clean-up-workingset.patch

This patch will shortly appear at
     https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-mglru-clean-up-workingset.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: Yu Zhao <yuzhao@google.com>
Subject: mm/mglru: clean up workingset
Date: Sun, 1 Dec 2024 20:28:18 -0700

Patch series "mm/mglru: performance optimizations".

This series improves performance for some previously discussed test cases.
Most of the code changes gathered here has been floating on the mailing
list [1][2].  They are now properly organized and have gone through
various benchmarks on both client and server devices, including Android,
FIO, memcached, multiple VMs and MongoDB.

[1] https://lore.kernel.org/CAOUHufahuWcKf5f1Sg3emnqX+cODuR=2TQo7T4Gr-QYLujn4RA@mail.gmail.com/
[2] https://lore.kernel.org/CAOUHufawNerxqLm7L9Yywp3HJFiYVrYO26ePUb1jH-qxNGWzyA@mail.gmail.com/


This patch (of 6):

Move VM_BUG_ON_FOLIO() to cover both the default and MGLRU paths.  Also
use a pair of rcu_read_lock() and rcu_read_unlock() within each path, to
improve readability.

This change should not have any side effects.

Link: https://lkml.kernel.org/r/20241202032823.2741019-1-yuzhao@google.com
Link: https://lkml.kernel.org/r/20241202032823.2741019-2-yuzhao@google.com
Signed-off-by: Yu Zhao <yuzhao@google.com>
Tested-by: Kalesh Singh <kaleshsingh@google.com>
Cc: Bharata B Rao <bharata@amd.com>
Cc: David Stevens <stevensd@chromium.org>
Cc: Kairui Song <kasong@tencent.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 mm/workingset.c |   23 +++++++++++------------
 1 file changed, 11 insertions(+), 12 deletions(-)

--- a/mm/workingset.c~mm-mglru-clean-up-workingset
+++ a/mm/workingset.c
@@ -428,17 +428,17 @@ bool workingset_test_recent(void *shadow
 	struct pglist_data *pgdat;
 	unsigned long eviction;
 
-	rcu_read_lock();
-
 	if (lru_gen_enabled()) {
-		bool recent = lru_gen_test_recent(shadow, file,
-				&eviction_lruvec, &eviction, workingset);
+		bool recent;
 
+		rcu_read_lock();
+		recent = lru_gen_test_recent(shadow, file, &eviction_lruvec,
+					     &eviction, workingset);
 		rcu_read_unlock();
 		return recent;
 	}
 
-
+	rcu_read_lock();
 	unpack_shadow(shadow, &memcgid, &pgdat, &eviction, workingset);
 	eviction <<= bucket_order;
 
@@ -459,14 +459,12 @@ bool workingset_test_recent(void *shadow
 	 * configurations instead.
 	 */
 	eviction_memcg = mem_cgroup_from_id(memcgid);
-	if (!mem_cgroup_disabled() &&
-	    (!eviction_memcg || !mem_cgroup_tryget(eviction_memcg))) {
-		rcu_read_unlock();
-		return false;
-	}
-
+	if (!mem_cgroup_tryget(eviction_memcg))
+		eviction_memcg = NULL;
 	rcu_read_unlock();
 
+	if (!mem_cgroup_disabled() && !eviction_memcg)
+		return false;
 	/*
 	 * Flush stats (and potentially sleep) outside the RCU read section.
 	 *
@@ -544,6 +542,8 @@ void workingset_refault(struct folio *fo
 	bool workingset;
 	long nr;
 
+	VM_BUG_ON_FOLIO(!folio_test_locked(folio), folio);
+
 	if (lru_gen_enabled()) {
 		lru_gen_refault(folio, shadow);
 		return;
@@ -558,7 +558,6 @@ void workingset_refault(struct folio *fo
 	 * is actually experiencing the refault event. Make sure the folio is
 	 * locked to guarantee folio_memcg() stability throughout.
 	 */
-	VM_BUG_ON_FOLIO(!folio_test_locked(folio), folio);
 	nr = folio_nr_pages(folio);
 	memcg = folio_memcg(folio);
 	pgdat = folio_pgdat(folio);
_

Patches currently in -mm which might be from yuzhao@google.com are

mm-mglru-clean-up-workingset.patch
mm-mglru-optimize-deactivation.patch
mm-mglru-rework-aging-feedback.patch
mm-mglru-rework-type-selection.patch
mm-mglru-rework-refault-detection.patch
mm-mglru-rework-workingset-protection.patch