linux-kernel - Re: [PATCH] mm/zswap: reduce the size of the compression buffer to a single page

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Message-Id: <20250820224659.88528-1-sj@kernel.org>
Date: Wed, 20 Aug 2025 15:46:59 -0700
From: SeongJae Park <sj@...nel.org>
To: Nhat Pham <nphamcs@...il.com>
Cc: SeongJae Park <sj@...nel.org>,
	akpm@...ux-foundation.org,
	hannes@...xchg.org,
	yosry.ahmed@...ux.dev,
	chengming.zhou@...ux.dev,
	herbert@...dor.apana.org.au,
	linux-mm@...ck.org,
	kernel-team@...a.com,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] mm/zswap: reduce the size of the compression buffer to a single page

On Wed, 20 Aug 2025 11:15:47 -0700 Nhat Pham <nphamcs@...il.com> wrote:

> Reduce the compression buffer size from 2 * PAGE_SIZE to only one page,
> as the compression output (in the success case) should not exceed the
> length of the input.
> 
> In the past, Chengming tried to reduce the compression buffer size, but
> ran into issues with the LZO algorithm (see [2]). Herbert Xu reported
> that the issue has been fixed (see [3]). Now we should have the
> guarantee that compressors' output should not exceed one page in the
> success case, and the algorithm will just report failure otherwise.
> 
> With this patch, we save one page per cpu (per compression algorithm).
> 
> [1]: https://lore.kernel.org/linux-mm/20231213-zswap-dstmem-v4-1-f228b059dd89@bytedance.com/

This is not mentioned anywhere.  Probably you added this as a reference for the
past work from Chengming?

> [2]: https://lore.kernel.org/lkml/0000000000000b05cd060d6b5511@google.com/
> [3]: https://lore.kernel.org/linux-mm/aKUmyl5gUFCdXGn-@gondor.apana.org.au/
> 
> Co-developed-by: Chengming Zhou <chengming.zhou@...ux.dev>
> Signed-off-by: Chengming Zhou <chengming.zhou@...ux.dev>
> Signed-off-by: Nhat Pham <nphamcs@...il.com>

Acked-by: SeongJae Park <sj@...nel.org>

[...]


Thanks,
SJ