From: Muhammad Usama Anjum <usama.anjum@arm.com>
To: Kevin Brodsky <kevin.brodsky@arm.com>,
linux-mm@kvack.org, linux-kselftest@vger.kernel.org
Cc: usama.anjum@arm.com, linux-kernel@vger.kernel.org,
Andrew Morton <akpm@linux-foundation.org>,
David Hildenbrand <david@kernel.org>, Dev Jain <dev.jain@arm.com>,
Lorenzo Stoakes <lorenzo.stoakes@oracle.com>,
Mark Brown <broonie@kernel.org>,
Ryan Roberts <ryan.roberts@arm.com>,
Shuah Khan <shuah@kernel.org>
Subject: Re: [PATCH v3 7/9] selftests/mm: fix faulting-in code in pagemap_ioctl test
Date: Thu, 22 Jan 2026 17:43:09 +0000 [thread overview]
Message-ID: <189f12fb-a558-41aa-9194-19053c6b350b@arm.com> (raw)
In-Reply-To: <20260122170224.4056513-8-kevin.brodsky@arm.com>
On 22/01/2026 5:02 pm, 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.
>
> We don't need to copy all that memory anyway. Just fault in every
> page.
>
> While at it also make sure to compute the number of pages once using
> simple integer arithmetic instead of ceilf() and implicit
> conversions.
>
> Fixes: 46036188ea1f ("selftests/mm: build with -O2")
> Cc: Usama Anjum <Usama.Anjum@arm.com>
> Acked-by: David Hildenbrand (Red Hat) <david@kernel.org>
> Reviewed-by: Dev Jain <dev.jain@arm.com>
> Signed-off-by: Kevin Brodsky <kevin.brodsky@arm.com>
> ---
Reviewed-by: Muhammad Usama Anjum <usama.anjum@arm.com>
next prev parent reply other threads:[~2026-01-22 17:43 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-01-22 17:02 [PATCH v3 0/9] Various mm kselftests improvements/fixes Kevin Brodsky
2026-01-22 17:02 ` [PATCH v3 1/9] selftests/mm: default KDIR to build directory Kevin Brodsky
2026-01-22 17:02 ` [PATCH v3 2/9] selftests/mm: remove flaky header check Kevin Brodsky
2026-01-22 17:02 ` [PATCH v3 3/9] selftests/mm: pass down full CC and CFLAGS to check_config.sh Kevin Brodsky
2026-01-22 17:02 ` [PATCH v3 4/9] selftests/mm: fix usage of FORCE_READ() in cow tests Kevin Brodsky
2026-01-22 17:02 ` [PATCH v3 5/9] selftests/mm: check that FORCE_READ() succeeded Kevin Brodsky
2026-01-22 17:36 ` Usama Anjum
2026-01-23 8:20 ` Kevin Brodsky
2026-01-22 22:18 ` David Hildenbrand (Red Hat)
2026-01-23 8:17 ` Kevin Brodsky
2026-01-22 17:02 ` [PATCH v3 6/9] selftests/mm: introduce helper to read every page Kevin Brodsky
2026-01-22 17:39 ` Muhammad Usama Anjum
2026-01-22 22:20 ` David Hildenbrand (Red Hat)
2026-01-23 8:25 ` Kevin Brodsky
2026-01-22 17:02 ` [PATCH v3 7/9] selftests/mm: fix faulting-in code in pagemap_ioctl test Kevin Brodsky
2026-01-22 17:43 ` Muhammad Usama Anjum [this message]
2026-01-22 17:02 ` [PATCH v3 8/9] selftests/mm: fix exit code in pagemap_ioctl Kevin Brodsky
2026-01-22 17:02 ` [PATCH v3 9/9] selftests/mm: report SKIP in pfnmap if a check fails Kevin Brodsky
2026-01-22 22:23 ` David Hildenbrand (Red Hat)
2026-01-22 18:25 ` [PATCH v3 0/9] Various mm kselftests improvements/fixes Andrew Morton
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