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

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Message-ID: <aKVbqi6wd3Spz-TM@gondor.apana.org.au>
Date: Wed, 20 Aug 2025 13:22:50 +0800
From: Herbert Xu <herbert@...dor.apana.org.au>
To: Chris Li <chrisl@...nel.org>
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 10:20:45PM -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.

Cheers,
-- 
Email: Herbert Xu <herbert@...dor.apana.org.au>
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt