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Date: Wed, 18 Mar 2026 13:51:04 -0700
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From: Shakeel Butt <shakeel.butt@linux.dev>
To: Johannes Weiner <hannes@cmpxchg.org>
Cc: Andrew Morton <akpm@linux-foundation.org>, 
	David Hildenbrand <david@kernel.org>, Yosry Ahmed <yosry.ahmed@linux.dev>, Zi Yan <ziy@nvidia.com>, 
	"Liam R. Howlett" <Liam.Howlett@oracle.com>, Usama Arif <usama.arif@linux.dev>, 
	Kiryl Shutsemau <kas@kernel.org>, Dave Chinner <david@fromorbit.com>, 
	Roman Gushchin <roman.gushchin@linux.dev>, linux-mm@kvack.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v3 5/7] mm: list_lru: introduce caller locking for
 additions and deletions
Message-ID: <absO1Bg_exH4llmH@linux.dev>
References: <20260318200352.1039011-1-hannes@cmpxchg.org>
 <20260318200352.1039011-6-hannes@cmpxchg.org>
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On Wed, Mar 18, 2026 at 03:53:23PM -0400, Johannes Weiner wrote:
> Locking is currently internal to the list_lru API. However, a caller
> might want to keep auxiliary state synchronized with the LRU state.
> 
> For example, the THP shrinker uses the lock of its custom LRU to keep
> PG_partially_mapped and vmstats consistent.
> 
> To allow the THP shrinker to switch to list_lru, provide normal and
> irqsafe locking primitives as well as caller-locked variants of the
> addition and deletion functions.
> 
> Reviewed-by: David Hildenbrand (Arm) <david@kernel.org>
> Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>

One nit below, other than that:

Acked-by: Shakeel Butt <shakeel.butt@linux.dev>

>  
> -static inline void lock_list_lru(struct list_lru_one *l, bool irq)
> +static inline void lock_list_lru(struct list_lru_one *l, bool irq,
> +				 unsigned long *irq_flags)
>  {
> -	if (irq)
> +	if (irq_flags)
> +		spin_lock_irqsave(&l->lock, *irq_flags);
> +	else if (irq)

If we move __list_lru_walk_one to use irq_flags then we can remove the irq
param. It is reclaim code path and I don't think additional cost of irqsave
would matter here.