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

From: Muhammad Usama Anjum <usama.anjum@collabora.com>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: usama.anjum@collabora.com, Shuah Khan <shuah@kernel.org>,
	David Hildenbrand <david@redhat.com>,
	Lorenzo Stoakes <lorenzo.stoakes@oracle.com>,
	"Liam R. Howlett" <Liam.Howlett@oracle.com>,
	Vlastimil Babka <vbabka@suse.cz>, Mike Rapoport <rppt@kernel.org>,
	Suren Baghdasaryan <surenb@google.com>,
	Michal Hocko <mhocko@suse.com>, Jason Gunthorpe <jgg@ziepe.ca>,
	John Hubbard <jhubbard@nvidia.com>, Peter Xu <peterx@redhat.com>,
	Leon Romanovsky <leon@kernel.org>, Zi Yan <ziy@nvidia.com>,
	Baolin Wang <baolin.wang@linux.alibaba.com>,
	Nico Pache <npache@redhat.com>,
	Ryan Roberts <ryan.roberts@arm.com>, Dev Jain <dev.jain@arm.com>,
	Barry Song <baohua@kernel.org>,
	Paul Walmsley <paul.walmsley@sifive.com>,
	Palmer Dabbelt <palmer@dabbelt.com>,
	Albert Ou <aou@eecs.berkeley.edu>,
	Alexandre Ghiti <alex@ghiti.fr>,
	linux-kselftest@vger.kernel.org, linux-kernel@vger.kernel.org,
	linux-mm@kvack.org, linux-riscv@lists.infradead.org,
	kevin.brodsky@arm.com, kernel@collabora.com
Subject: Re: [PATCH v3 0/8] selftests/mm: Add compiler flags and fix found warnings
Date: Mon, 25 Aug 2025 12:14:52 +0500	[thread overview]
Message-ID: <a3928ec4-8c2f-4f04-bab4-9ef5c87c57de@collabora.com> (raw)
In-Reply-To: <20250822174259.bf4ed76a0da7d0d6f80ba2c1@linux-foundation.org>

On 8/23/25 5:42 AM, Andrew Morton wrote:
> On Fri, 22 Aug 2025 13:20:57 +0500 Muhammad Usama Anjum <usama.anjum@collabora.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

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