linux-kernel - Re: [PATCH v3 0/8] selftests/mm: Add compiler flags and fix found warnings

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Message-ID: <a3928ec4-8c2f-4f04-bab4-9ef5c87c57de@collabora.com>
Date: Mon, 25 Aug 2025 12:14:52 +0500
From: Muhammad Usama Anjum <usama.anjum@...labora.com>
To: Andrew Morton <akpm@...ux-foundation.org>
Cc: usama.anjum@...labora.com, Shuah Khan <shuah@...nel.org>,
 David Hildenbrand <david@...hat.com>,
 Lorenzo Stoakes <lorenzo.stoakes@...cle.com>,
 "Liam R. Howlett" <Liam.Howlett@...cle.com>, Vlastimil Babka
 <vbabka@...e.cz>, Mike Rapoport <rppt@...nel.org>,
 Suren Baghdasaryan <surenb@...gle.com>, Michal Hocko <mhocko@...e.com>,
 Jason Gunthorpe <jgg@...pe.ca>, John Hubbard <jhubbard@...dia.com>,
 Peter Xu <peterx@...hat.com>, Leon Romanovsky <leon@...nel.org>,
 Zi Yan <ziy@...dia.com>, Baolin Wang <baolin.wang@...ux.alibaba.com>,
 Nico Pache <npache@...hat.com>, Ryan Roberts <ryan.roberts@....com>,
 Dev Jain <dev.jain@....com>, Barry Song <baohua@...nel.org>,
 Paul Walmsley <paul.walmsley@...ive.com>, Palmer Dabbelt
 <palmer@...belt.com>, Albert Ou <aou@...s.berkeley.edu>,
 Alexandre Ghiti <alex@...ti.fr>, linux-kselftest@...r.kernel.org,
 linux-kernel@...r.kernel.org, linux-mm@...ck.org,
 linux-riscv@...ts.infradead.org, kevin.brodsky@....com, kernel@...labora.com
Subject: Re: [PATCH v3 0/8] selftests/mm: Add compiler flags and fix found
 warnings

On 8/23/25 5:42 AM, Andrew Morton wrote:
> On Fri, 22 Aug 2025 13:20:57 +0500 Muhammad Usama Anjum <usama.anjum@...labora.com> wrote:
> 
>> Recently, I reviewed a patch on the mm/kselftest mailing list about a
>> test which had obvious type mismatch fix in it. It was strange why that
>> wasn't caught during development and when patch was accepted. This led
>> me to discover that those extra compiler options to catch these warnings
>> aren't being used. When I added them, I found tens of warnings in just
>> mm suite.
>>
>> In this series, I'm adding these flags and fixing those warnings. In the
>> last try several months ago [1], I'd patches for individual tests. I've
>> made patches better by grouping the same type of fixes together. Hence
>> there is no changelog for individual patches.
> 
> I think it would be best to avoid adding warnings to selftests which
> aren't present in the main kernel code.  If only to avoid surprising
> people over what isn't permissible in selftests/.
> 
> In particular, there's an expectation that we can do
> 
> #else
> static inline int some_stub(type1 arg1, type2 arg2)
> {
> }
> #endif
> 
> without warning.  We do this extensively.

I'm only adding -Wunreachable-code -Wunused flags now. The above shouldn't
cause any warnings. I'll double check again in next series.

> 
> Also, please be aware that there's already a patch in mm-new which
> centralizes selftests' __maybe_unused definition.
> https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/selftests-centralise-maybe-unused-definition-in-kselftesth.patch
I'll rebase on top of it and send again.

-- 
---
Thanks,
Usama