linux-kernel - Re: [PATCH] mm: zswap: Use SG list decompression APIs from zsmalloc

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Message-ID: <CAKEwX=Mr_TRMBkDaX_qqDAWrK0H5oPQejhp9JApw7Mw_2PLYCA@mail.gmail.com>
Date: Tue, 3 Feb 2026 15:18:25 -0800
From: Nhat Pham <nphamcs@...il.com>
To: Sergey Senozhatsky <senozhatsky@...omium.org>
Cc: Yosry Ahmed <yosry.ahmed@...ux.dev>, Herbert Xu <herbert@...dor.apana.org.au>, 
	Andrew Morton <akpm@...ux-foundation.org>, Johannes Weiner <hannes@...xchg.org>, 
	Chengming Zhou <chengming.zhou@...ux.dev>, linux-mm@...ck.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] mm: zswap: Use SG list decompression APIs from zsmalloc

On Tue, Jan 20, 2026 at 7:49 PM Sergey Senozhatsky
<senozhatsky@...omium.org> wrote:
>
> On (26/01/21 01:36), Yosry Ahmed wrote:
> > Use the new zs_obj_read_sg_*() APIs in zswap_decompress(), instead of
> > zs_obj_read_*() APIs returning a linear address. The SG list is passed
> > directly to the crypto API, simplifying the logic and dropping the
> > workaround that copies highmem addresses to a buffer. The crypto API
> > should internally linearize the SG list if needed.
> >
> > This avoids the memcpy() in zsmalloc for objects spanning multiple
> > pages, although an equivalent operation will be done internally by
> > acomp/scomp. However, in the future compression algorithms could support
> > handling discontiguous SG lists, completely eliminating the copying for
> > spanning objects.
>

Ah for some reasons, I did not see this one - I reviewed on the other
thread. My apologies.

Anyway, just to re-iterate:

Acked-by: Nhat Pham <nphamcs@...il.com>