+ memcg-v1-no-need-for-memcg-locking-for-mglru.patch added to mm-unstable branch

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

The patch titled
     Subject: memcg-v1: no need for memcg locking for MGLRU
has been added to the -mm mm-unstable branch.  Its filename is
     memcg-v1-no-need-for-memcg-locking-for-mglru.patch

This patch will shortly appear at
     https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/memcg-v1-no-need-for-memcg-locking-for-mglru.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: Shakeel Butt <shakeel.butt@linux.dev>
Subject: memcg-v1: no need for memcg locking for MGLRU
Date: Thu, 24 Oct 2024 18:23:02 -0700

While updating the generation of the folios, MGLRU requires that the
folio's memcg association remains stable.  With the charge migration
deprecated, there is no need for MGLRU to acquire locks to keep the folio
and memcg association stable.

Link: https://lkml.kernel.org/r/20241025012304.2473312-6-shakeel.butt@linux.dev
Signed-off-by: Shakeel Butt <shakeel.butt@linux.dev>
Reviewed-by: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Hugh Dickins <hughd@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Yosry Ahmed <yosryahmed@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 mm/vmscan.c |   11 -----------
 1 file changed, 11 deletions(-)

--- a/mm/vmscan.c~memcg-v1-no-need-for-memcg-locking-for-mglru
+++ a/mm/vmscan.c
@@ -3662,10 +3662,6 @@ static void walk_mm(struct mm_struct *mm
 		if (walk->seq != max_seq)
 			break;
 
-		/* folio_update_gen() requires stable folio_memcg() */
-		if (!mem_cgroup_trylock_pages(memcg))
-			break;
-
 		/* the caller might be holding the lock for write */
 		if (mmap_read_trylock(mm)) {
 			err = walk_page_range(mm, walk->next_addr, ULONG_MAX, &mm_walk_ops, walk);
@@ -3673,8 +3669,6 @@ static void walk_mm(struct mm_struct *mm
 			mmap_read_unlock(mm);
 		}
 
-		mem_cgroup_unlock_pages();
-
 		if (walk->batched) {
 			spin_lock_irq(&lruvec->lru_lock);
 			reset_batch_size(walk);
@@ -4096,10 +4090,6 @@ bool lru_gen_look_around(struct page_vma
 		}
 	}
 
-	/* folio_update_gen() requires stable folio_memcg() */
-	if (!mem_cgroup_trylock_pages(memcg))
-		return true;
-
 	arch_enter_lazy_mmu_mode();
 
 	pte -= (addr - start) / PAGE_SIZE;
@@ -4144,7 +4134,6 @@ bool lru_gen_look_around(struct page_vma
 	}
 
 	arch_leave_lazy_mmu_mode();
-	mem_cgroup_unlock_pages();
 
 	/* feedback from rmap walkers to page table walkers */
 	if (mm_state && suitable_to_scan(i, young))
_

Patches currently in -mm which might be from shakeel.butt@linux.dev are

mm-optimize-truncation-of-shadow-entries.patch
mm-optimize-invalidation-of-shadow-entries.patch
mm-truncate-reset-xa_has_values-flag-on-each-iteration.patch
memcg-add-tracing-for-memcg-stat-updates.patch
memcg-add-tracing-for-memcg-stat-updates-v2.patch
memcg-v1-fully-deprecate-move_charge_at_immigrate.patch
memcg-v1-remove-charge-move-code.patch
memcg-v1-no-need-for-memcg-locking-for-dirty-tracking.patch
memcg-v1-no-need-for-memcg-locking-for-writeback-tracking.patch
memcg-v1-no-need-for-memcg-locking-for-mglru.patch
memcg-v1-remove-memcg-move-locking-code.patch