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Date: Fri, 2 Feb 2024 00:15:26 +0000
In-Reply-To: <20240201-b4-zswap-invalidate-entry-v1-3-56ed496b6e55@bytedance.com>
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Message-ID: <Zbw0HjFkvMG4PT9l@google.com>
Subject: Re: [PATCH 3/6] mm/zswap: stop lru list shrinking when encounter warm region
From: Yosry Ahmed <yosryahmed@google.com>
To: Chengming Zhou <zhouchengming@bytedance.com>
Cc: Nhat Pham <nphamcs@gmail.com>, Johannes Weiner <hannes@cmpxchg.org>, 
	Andrew Morton <akpm@linux-foundation.org>, linux-kernel@vger.kernel.org, 
	linux-mm@kvack.org
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On Thu, Feb 01, 2024 at 03:49:03PM +0000, Chengming Zhou wrote:
> When the shrinker encounter an existing folio in swap cache, it means
> we are shrinking into the warmer region. We should terminate shrinking
> if we're in the dynamic shrinker context.
> 
> This patch add LRU_STOP to support this, to avoid overshrinking.
> 
> Signed-off-by: Chengming Zhou <zhouchengming@bytedance.com>

LGTM with one comment below.

Reviewed-by: Yosry Ahmed <yosryahmed@google.com>

> ---
>  include/linux/list_lru.h | 1 +
>  mm/list_lru.c            | 3 +++
>  mm/zswap.c               | 4 +++-
>  3 files changed, 7 insertions(+), 1 deletion(-)
> 
> diff --git a/include/linux/list_lru.h b/include/linux/list_lru.h
> index f2882a820690..5633e970144b 100644
> --- a/include/linux/list_lru.h
> +++ b/include/linux/list_lru.h
> @@ -24,6 +24,7 @@ enum lru_status {
>  	LRU_SKIP,		/* item cannot be locked, skip */
>  	LRU_RETRY,		/* item not freeable. May drop the lock
>  				   internally, but has to return locked. */
> +	LRU_STOP,		/* stop lru list walking */

nit: Should we add "May drop the lock internally, but has to return
locked" like LRU_RETRY and LRU_REMOVED_RETRY?

>  };
>  
>  struct list_lru_one {
[..]