linux-kernel - Re: [PATCH v2 5/6] mm: zswap: store incompressible page as-is

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Message-ID: <CAKEwX=Oqe8qz0YKi1pJaEgXAPC-7cXg7_NRfXb1_0VJp35X7AQ@mail.gmail.com>
Date: Fri, 12 Jul 2024 15:47:30 -0700
From: Nhat Pham <nphamcs@...il.com>
To: Chengming Zhou <chengming.zhou@...ux.dev>
Cc: Takero Funaki <flintglass@...il.com>, Johannes Weiner <hannes@...xchg.org>, 
	Yosry Ahmed <yosryahmed@...gle.com>, Jonathan Corbet <corbet@....net>, 
	Andrew Morton <akpm@...ux-foundation.org>, 
	Domenico Cerasuolo <cerasuolodomenico@...il.com>, linux-mm@...ck.org, linux-doc@...r.kernel.org, 
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 5/6] mm: zswap: store incompressible page as-is

On Tue, Jul 9, 2024 at 6:26 AM Chengming Zhou <chengming.zhou@...ux.dev> wrote:
>
> On 2024/7/8 21:44, Takero Funaki wrote:
> > 2024年7月8日(月) 12:56 Chengming Zhou <chengming.zhou@...ux.dev>:
> >
> >>>        comp_ret = crypto_wait_req(crypto_acomp_compress(acomp_ctx->req), &acomp_ctx->wait);
> >>>        dlen = acomp_ctx->req->dlen;
> >>> -     if (comp_ret)
> >>> +
> >>> +     /* coa_compress returns -EINVAL for errors including insufficient dlen */
> >>> +     if (comp_ret && comp_ret != -EINVAL)
> >>>                goto unlock;
> >>
> >> Seems we don't need to care about? "comp_ret" is useless anymore.
> >>
> >> Just:
> >>
> >> if (comp_ret || dlen > PAGE_SIZE - 64)
> >>          dlen = PAGE_SIZE;
> >>
> >> And remove the checkings of comp_ret at the end.
> >>
> >
> >>
> >> We actually don't need to hold mutex if we are just copying folio.
> >>
> >> Thanks.
> >>
> >
> > Thanks for reviewing.
> >
> > For comp_ret, can we consolidate all possible error codes as
> > incompressible data?
>
> Maybe we still want these debug counters? I'm not sure.

I'm a bit torn, but ATM I have no strong opinions on these two error
codes. If you do decide to consolidate these two, may I ask you to
separate it into its own patch so that we can review + discuss it
separately?