The quilt patch titled
Subject: memcg-v1: no need for memcg locking for MGLRU
has been removed from the -mm tree. Its filename was
memcg-v1-no-need-for-memcg-locking-for-mglru.patch
This patch was dropped because it was merged into the mm-stable branch
of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
------------------------------------------------------
From: Shakeel Butt <shakeel.butt@xxxxxxxxx>
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.
[yuzhao@xxxxxxxxxx: remove !rcu_read_lock_held() assertion]
Link: https://lkml.kernel.org/r/ZykEtcHrQRq-KrBC@xxxxxxxxxx
Link: https://syzkaller.appspot.com/bug?extid=24f45b8beab9788e467e
Link: https://lore.kernel.org/lkml/67294349.050a0220.701a.0010.GAE@xxxxxxxxxx/
[akpm@xxxxxxxxxxxxxxxxxxxx: remove now-unused local]
[shakeel.butt@xxxxxxxxx: folio_rcu() fixup, per Yu Zhao]
Link: https://lkml.kernel.org/r/iwmabnye3nl4merealrawt3bdvfii2pwavwrddrqpraoveet7h@ezrsdhjwwej7
Link: https://lkml.kernel.org/r/20241025012304.2473312-6-shakeel.butt@xxxxxxxxx
Signed-off-by: Shakeel Butt <shakeel.butt@xxxxxxxxx>
Reviewed-by: Roman Gushchin <roman.gushchin@xxxxxxxxx>
Cc: Hugh Dickins <hughd@xxxxxxxxxx>
Cc: Johannes Weiner <hannes@xxxxxxxxxxx>
Cc: Michal Hocko <mhocko@xxxxxxxx>
Cc: Muchun Song <muchun.song@xxxxxxxxx>
Cc: Yosry Ahmed <yosryahmed@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/vmscan.c | 16 +---------------
1 file changed, 1 insertion(+), 15 deletions(-)
--- a/mm/vmscan.c~memcg-v1-no-need-for-memcg-locking-for-mglru
+++ a/mm/vmscan.c
@@ -3137,7 +3137,6 @@ static int folio_update_gen(struct folio
unsigned long new_flags, old_flags = READ_ONCE(folio->flags);
VM_WARN_ON_ONCE(gen >= MAX_NR_GENS);
- VM_WARN_ON_ONCE(!rcu_read_lock_held());
do {
/* lru_gen_del_folio() has isolated this page? */
@@ -3353,7 +3352,7 @@ static struct folio *get_pfn_folio(unsig
if (folio_nid(folio) != pgdat->node_id)
return NULL;
- if (folio_memcg_rcu(folio) != memcg)
+ if (folio_memcg(folio) != memcg)
return NULL;
/* file VMAs can contain anon pages from COW */
@@ -3649,10 +3648,8 @@ static void walk_mm(struct mm_struct *mm
.p4d_entry = walk_pud_range,
.walk_lock = PGWALK_RDLOCK,
};
-
int err;
struct lruvec *lruvec = walk->lruvec;
- struct mem_cgroup *memcg = lruvec_memcg(lruvec);
walk->next_addr = FIRST_USER_ADDRESS;
@@ -3665,10 +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);
@@ -3676,8 +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);
@@ -4099,10 +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;
@@ -4147,7 +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@xxxxxxxxx are
