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

[Nhat Pham]

On Wed, Aug 20, 2025 at 3:47 PM SeongJae Park <sj@xxxxxxxxxx> wrote:
>
> On Wed, 20 Aug 2025 11:15:47 -0700 Nhat Pham <nphamcs@xxxxxxxxx> 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

Yeah, this should include the reference below. My bad. So it should be:

In the past, Chengming tried to reduce the compression buffer size
(see [1]), but

Andrew, would it be OK if you fix it for me when you put this patch in
your tree :) Or I can also send a new version if that's better. Thank
you!

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

Thanks for taking a look, SJ!

>
> > [2]: https://lore.kernel.org/lkml/0000000000000b05cd060d6b5511@xxxxxxxxxx/
> > [3]: https://lore.kernel.org/linux-mm/aKUmyl5gUFCdXGn-@xxxxxxxxxxxxxxxxxxx/
> >
> > Co-developed-by: Chengming Zhou <chengming.zhou@xxxxxxxxx>
> > Signed-off-by: Chengming Zhou <chengming.zhou@xxxxxxxxx>
> > Signed-off-by: Nhat Pham <nphamcs@xxxxxxxxx>
>
> Acked-by: SeongJae Park <sj@xxxxxxxxxx>