From: Kevin Brodsky <kevin.brodsky@arm.com>
To: "David Hildenbrand (Red Hat)" <david@kernel.org>,
linux-mm@kvack.org, linux-kselftest@vger.kernel.org
Cc: linux-kernel@vger.kernel.org,
Andrew Morton <akpm@linux-foundation.org>,
Lorenzo Stoakes <lorenzo.stoakes@oracle.com>,
Mark Brown <broonie@kernel.org>,
Ryan Roberts <ryan.roberts@arm.com>,
Shuah Khan <shuah@kernel.org>, Usama Anjum <Usama.Anjum@arm.com>
Subject: Re: [PATCH v2 6/8] selftests/mm: fix faulting-in code in pagemap_ioctl test
Date: Mon, 19 Jan 2026 14:30:45 +0100 [thread overview]
Message-ID: <a78f2fdf-ef4d-4570-b592-b2943b6ac06d@arm.com> (raw)
In-Reply-To: <cd9e1fca-81ef-4eaa-aea1-aac6dd00623d@kernel.org>
On 19/01/2026 12:09, David Hildenbrand (Red Hat) wrote:
> On 1/7/26 17:48, Kevin Brodsky wrote:
>> One of the pagemap_ioctl tests attempts to fault in pages by
>> memcpy()'ing them to an unused buffer. This probably worked
>> originally, but since commit 46036188ea1f ("selftests/mm: build with
>> -O2") the compiler is free to optimise away that unused buffer and
>> the memcpy() with it. As a result there might not be any resident
>> page in the mapping and the test may fail.
>
> Yes, I assume so. Using FORCE_READ() etc is the way to go.
>
>
> Should we add
>
> Fixes: 46036188ea1f ("selftests/mm: build with -O2")
Yes that seems reasonable, the test was arguably broken to start with
but it is this commit that revealed it ;)
- Kevin
next prev parent reply other threads:[~2026-01-19 13:30 UTC|newest]
Thread overview: 36+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-01-07 16:48 [PATCH v2 0/8] Various mm kselftests improvements/fixes Kevin Brodsky
2026-01-07 16:48 ` [PATCH v2 1/8] selftests/mm: default KDIR to build directory Kevin Brodsky
2026-01-07 16:48 ` [PATCH v2 2/8] selftests/mm: remove flaky header check Kevin Brodsky
2026-01-07 16:48 ` [PATCH v2 3/8] selftests/mm: pass down full CC and CFLAGS to check_config.sh Kevin Brodsky
2026-01-07 16:59 ` Mark Brown
2026-01-07 16:48 ` [PATCH v2 4/8] selftests/mm: fix usage of FORCE_READ() in cow tests Kevin Brodsky
2026-01-08 0:56 ` SeongJae Park
2026-01-08 2:04 ` wang lian
2026-01-08 2:07 ` [PATCH v2 7/8] selftests/mm: fix exit code in pagemap_ioctl wang lian
2026-01-19 10:50 ` [PATCH v2 4/8] selftests/mm: fix usage of FORCE_READ() in cow tests David Hildenbrand (Red Hat)
2026-01-19 13:24 ` Kevin Brodsky
2026-01-22 5:40 ` Dev Jain
2026-01-07 16:48 ` [PATCH v2 5/8] selftests/mm: introduce helper to read every page in range Kevin Brodsky
2026-01-09 1:30 ` SeongJae Park
2026-01-12 9:37 ` Kevin Brodsky
2026-01-13 0:55 ` SeongJae Park
2026-01-19 10:55 ` David Hildenbrand (Red Hat)
2026-01-19 13:29 ` Kevin Brodsky
2026-01-22 6:05 ` Dev Jain
2026-01-07 16:48 ` [PATCH v2 6/8] selftests/mm: fix faulting-in code in pagemap_ioctl test Kevin Brodsky
2026-01-19 11:09 ` David Hildenbrand (Red Hat)
2026-01-19 13:30 ` Kevin Brodsky [this message]
2026-01-22 6:16 ` Dev Jain
2026-01-07 16:48 ` [PATCH v2 7/8] selftests/mm: fix exit code in pagemap_ioctl Kevin Brodsky
2026-01-08 1:06 ` SeongJae Park
2026-01-08 2:12 ` wang lian
2026-01-22 6:22 ` Dev Jain
2026-01-07 16:48 ` [PATCH v2 8/8] selftests/mm: report SKIP in pfnmap if a check fails Kevin Brodsky
2026-01-12 9:34 ` Ryan Roberts
2026-01-12 10:03 ` Kevin Brodsky
2026-01-12 10:25 ` Ryan Roberts
2026-01-19 11:16 ` David Hildenbrand (Red Hat)
2026-01-19 14:26 ` Ryan Roberts
2026-01-19 14:32 ` David Hildenbrand (Red Hat)
2026-01-20 16:27 ` Ryan Roberts
2026-01-21 13:45 ` Kevin Brodsky
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