linux-kernel - Re: [PATCH v4] mm/zswap: store <PAGE_SIZE compression failed page as-is

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Message-ID: <CAF8kJuOJsZ2RbvFedfKADVqa0TUrkO-ceqrtaMXgiHAS0V19hw@mail.gmail.com>
Date: Thu, 21 Aug 2025 13:42:11 -0700
From: Chris Li <chrisl@...nel.org>
To: Herbert Xu <herbert@...dor.apana.org.au>
Cc: Barry Song <21cnbao@...il.com>, SeongJae Park <sj@...nel.org>, 
	Andrew Morton <akpm@...ux-foundation.org>, Chengming Zhou <chengming.zhou@...ux.dev>, 
	Johannes Weiner <hannes@...xchg.org>, Nhat Pham <nphamcs@...il.com>, 
	Yosry Ahmed <yosry.ahmed@...ux.dev>, kernel-team@...a.com, linux-kernel@...r.kernel.org, 
	linux-mm@...ck.org, Takero Funaki <flintglass@...il.com>, 
	David Hildenbrand <david@...hat.com>, Baoquan He <bhe@...hat.com>, Kairui Song <kasong@...cent.com>
Subject: Re: [PATCH v4] mm/zswap: store <PAGE_SIZE compression failed page as-is

On Tue, Aug 19, 2025 at 10:23 PM Herbert Xu <herbert@...dor.apana.org.au> wrote:
>
> On Tue, Aug 19, 2025 at 10:20:45PM -0700, Chris Li wrote:
> >
> > In that case it is fair game for the caller to check for the error
> > other than -ENOSPC. If the return value is -EINPROGRESS during
> > synchronous crypto compression, it is a bug. We are not encouraged to
> > use WARN_ON, then having an error count to check that something truly
> > unlikely but possible to happen is better than folding it into
> > incompressible and pretend the error never happened. At least we can
> > know such an error case happened.
>
> Sure warning on -EINPROGRESS is fine.  But every other non-zero
> return value should be treated as incompressible.

Ack.

Thanks for the feedback.

Chris