Re: [PATCH v3 23/30] mm: do not open-code lruvec lock

[Baoquan He <bhe@redhat.com>]

On 01/14/26 at 07:32pm, Qi Zheng wrote:
> From: Qi Zheng <zhengqi.arch@bytedance.com>
> 
> Now we have lruvec_unlock(), lruvec_unlock_irq() and
> lruvec_unlock_irqrestore(), but not the paired lruvec_lock(),
                                  ~~ typo, 'no'?
> lruvec_lock_irq() and lruvec_lock_irqsave().
> 
> There is currently no use case for lruvec_lock_irqsave(), so only
> introduce lruvec_lock() and lruvec_lock_irq(), and change all open-code

  I didn't see lruvec_lock() is introduced in this patch, do I miss
  anthing?

> places to use these helper function. This looks cleaner and prepares for
> reparenting LRU pages, preventing user from missing RCU lock calls due to
> open-code lruvec lock.
> 
> Signed-off-by: Qi Zheng <zhengqi.arch@bytedance.com>
> ---
>  include/linux/memcontrol.h |  5 +++++
>  mm/vmscan.c                | 38 +++++++++++++++++++-------------------
>  2 files changed, 24 insertions(+), 19 deletions(-)
> 
> diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
> index f1556759d0d3f..4b6f20dc694ba 100644
> --- a/include/linux/memcontrol.h
> +++ b/include/linux/memcontrol.h
> @@ -1499,6 +1499,11 @@ static inline struct lruvec *parent_lruvec(struct lruvec *lruvec)
>  	return mem_cgroup_lruvec(memcg, lruvec_pgdat(lruvec));
>  }
>  
> +static inline void lruvec_lock_irq(struct lruvec *lruvec)
> +{
> +	spin_lock_irq(&lruvec->lru_lock);
> +}
> +
>  static inline void lruvec_unlock(struct lruvec *lruvec)
>  {
>  	spin_unlock(&lruvec->lru_lock);
> diff --git a/mm/vmscan.c b/mm/vmscan.c
> index f206d4dac9e77..c48ff6e05e004 100644
> --- a/mm/vmscan.c
> +++ b/mm/vmscan.c
> @@ -2020,7 +2020,7 @@ static unsigned long shrink_inactive_list(unsigned long nr_to_scan,
>  
>  	lru_add_drain();
>  
> -	spin_lock_irq(&lruvec->lru_lock);
> +	lruvec_lock_irq(lruvec);
>  
>  	nr_taken = isolate_lru_folios(nr_to_scan, lruvec, &folio_list,
>  				     &nr_scanned, sc, lru);
> @@ -2032,7 +2032,7 @@ static unsigned long shrink_inactive_list(unsigned long nr_to_scan,
>  	count_memcg_events(lruvec_memcg(lruvec), item, nr_scanned);
>  	__count_vm_events(PGSCAN_ANON + file, nr_scanned);
>  
> -	spin_unlock_irq(&lruvec->lru_lock);
> +	lruvec_unlock_irq(lruvec);
>  
>  	if (nr_taken == 0)
>  		return 0;
> @@ -2051,7 +2051,7 @@ static unsigned long shrink_inactive_list(unsigned long nr_to_scan,
>  	count_memcg_events(lruvec_memcg(lruvec), item, nr_reclaimed);
>  	count_vm_events(PGSTEAL_ANON + file, nr_reclaimed);
>  
> -	spin_lock_irq(&lruvec->lru_lock);
> +	lruvec_lock_irq(lruvec);
>  	lru_note_cost_unlock_irq(lruvec, file, stat.nr_pageout,
>  					nr_scanned - nr_reclaimed);
>  
> @@ -2130,7 +2130,7 @@ static void shrink_active_list(unsigned long nr_to_scan,
>  
>  	lru_add_drain();
>  
> -	spin_lock_irq(&lruvec->lru_lock);
> +	lruvec_lock_irq(lruvec);
>  
>  	nr_taken = isolate_lru_folios(nr_to_scan, lruvec, &l_hold,
>  				     &nr_scanned, sc, lru);
> @@ -2141,7 +2141,7 @@ static void shrink_active_list(unsigned long nr_to_scan,
>  		__count_vm_events(PGREFILL, nr_scanned);
>  	count_memcg_events(lruvec_memcg(lruvec), PGREFILL, nr_scanned);
>  
> -	spin_unlock_irq(&lruvec->lru_lock);
> +	lruvec_unlock_irq(lruvec);
>  
>  	while (!list_empty(&l_hold)) {
>  		struct folio *folio;
> @@ -2197,7 +2197,7 @@ static void shrink_active_list(unsigned long nr_to_scan,
>  	count_memcg_events(lruvec_memcg(lruvec), PGDEACTIVATE, nr_deactivate);
>  	mod_node_page_state(pgdat, NR_ISOLATED_ANON + file, -nr_taken);
>  
> -	spin_lock_irq(&lruvec->lru_lock);
> +	lruvec_lock_irq(lruvec);
>  	lru_note_cost_unlock_irq(lruvec, file, 0, nr_rotated);
>  	trace_mm_vmscan_lru_shrink_active(pgdat->node_id, nr_taken, nr_activate,
>  			nr_deactivate, nr_rotated, sc->priority, file);
> @@ -3832,9 +3832,9 @@ static void walk_mm(struct mm_struct *mm, struct lru_gen_mm_walk *walk)
>  		}
>  
>  		if (walk->batched) {
> -			spin_lock_irq(&lruvec->lru_lock);
> +			lruvec_lock_irq(lruvec);
>  			reset_batch_size(walk);
> -			spin_unlock_irq(&lruvec->lru_lock);
> +			lruvec_unlock_irq(lruvec);
>  		}
>  
>  		cond_resched();
> @@ -3993,7 +3993,7 @@ static bool inc_max_seq(struct lruvec *lruvec, unsigned long seq, int swappiness
>  	if (seq < READ_ONCE(lrugen->max_seq))
>  		return false;
>  
> -	spin_lock_irq(&lruvec->lru_lock);
> +	lruvec_lock_irq(lruvec);
>  
>  	VM_WARN_ON_ONCE(!seq_is_valid(lruvec));
>  
> @@ -4008,7 +4008,7 @@ static bool inc_max_seq(struct lruvec *lruvec, unsigned long seq, int swappiness
>  		if (inc_min_seq(lruvec, type, swappiness))
>  			continue;
>  
> -		spin_unlock_irq(&lruvec->lru_lock);
> +		lruvec_unlock_irq(lruvec);
>  		cond_resched();
>  		goto restart;
>  	}
> @@ -4043,7 +4043,7 @@ static bool inc_max_seq(struct lruvec *lruvec, unsigned long seq, int swappiness
>  	/* make sure preceding modifications appear */
>  	smp_store_release(&lrugen->max_seq, lrugen->max_seq + 1);
>  unlock:
> -	spin_unlock_irq(&lruvec->lru_lock);
> +	lruvec_unlock_irq(lruvec);
>  
>  	return success;
>  }
> @@ -4739,7 +4739,7 @@ static int evict_folios(unsigned long nr_to_scan, struct lruvec *lruvec,
>  	struct mem_cgroup *memcg = lruvec_memcg(lruvec);
>  	struct pglist_data *pgdat = lruvec_pgdat(lruvec);
>  
> -	spin_lock_irq(&lruvec->lru_lock);
> +	lruvec_lock_irq(lruvec);
>  
>  	scanned = isolate_folios(nr_to_scan, lruvec, sc, swappiness, &type, &list);
>  
> @@ -4748,7 +4748,7 @@ static int evict_folios(unsigned long nr_to_scan, struct lruvec *lruvec,
>  	if (evictable_min_seq(lrugen->min_seq, swappiness) + MIN_NR_GENS > lrugen->max_seq)
>  		scanned = 0;
>  
> -	spin_unlock_irq(&lruvec->lru_lock);
> +	lruvec_unlock_irq(lruvec);
>  
>  	if (list_empty(&list))
>  		return scanned;
> @@ -4786,9 +4786,9 @@ static int evict_folios(unsigned long nr_to_scan, struct lruvec *lruvec,
>  	walk = current->reclaim_state->mm_walk;
>  	if (walk && walk->batched) {
>  		walk->lruvec = lruvec;
> -		spin_lock_irq(&lruvec->lru_lock);
> +		lruvec_lock_irq(lruvec);
>  		reset_batch_size(walk);
> -		spin_unlock_irq(&lruvec->lru_lock);
> +		lruvec_unlock_irq(lruvec);
>  	}
>  
>  	mod_lruvec_state(lruvec, PGDEMOTE_KSWAPD + reclaimer_offset(sc),
> @@ -5226,7 +5226,7 @@ static void lru_gen_change_state(bool enabled)
>  		for_each_node(nid) {
>  			struct lruvec *lruvec = get_lruvec(memcg, nid);
>  
> -			spin_lock_irq(&lruvec->lru_lock);
> +			lruvec_lock_irq(lruvec);
>  
>  			VM_WARN_ON_ONCE(!seq_is_valid(lruvec));
>  			VM_WARN_ON_ONCE(!state_is_valid(lruvec));
> @@ -5234,12 +5234,12 @@ static void lru_gen_change_state(bool enabled)
>  			lruvec->lrugen.enabled = enabled;
>  
>  			while (!(enabled ? fill_evictable(lruvec) : drain_evictable(lruvec))) {
> -				spin_unlock_irq(&lruvec->lru_lock);
> +				lruvec_unlock_irq(lruvec);
>  				cond_resched();
> -				spin_lock_irq(&lruvec->lru_lock);
> +				lruvec_lock_irq(lruvec);
>  			}
>  
> -			spin_unlock_irq(&lruvec->lru_lock);
> +			lruvec_unlock_irq(lruvec);
>  		}
>  
>  		cond_resched();
> -- 
> 2.20.1
> 
>