From: Zi Yan <ziy@nvidia.com>
To: wang lian <lianux.mm@gmail.com>
Cc: akpm@linux-foundation.org, broonie@kernel.org, david@redhat.com,
lorenzo.stoakes@oracle.com, sj@kernel.org, linux-mm@kvack.org,
linux-kernel@vger.kernel.org, brauner@kernel.org,
gkwang@linx-info.com, jannh@google.com, Liam.Howlett@oracle.com,
ludovico.zy.wu@gmail.com, p1ucky0923@gmail.com,
richard.weiyang@gmail.com, ryncsn@gmail.com, shuah@kernel.org,
vbabka@suse.cz, zijing.zhang@proton.me
Subject: Re: [PATCH 1/2] selftests/mm: reuse FORCE_READ to replace "asm volatile("" : "+r" (XXX));"
Date: Fri, 18 Jul 2025 11:11:23 -0400 [thread overview]
Message-ID: <2173758C-0BFE-4AFE-BF46-A32F69F1CBCA@nvidia.com> (raw)
In-Reply-To: <20250717131857.59909-2-lianux.mm@gmail.com>
On 17 Jul 2025, at 9:18, wang lian wrote:
> Several mm selftests use the `asm volatile("" : "+r" (variable));`
> construct to force a read of a variable, preventing the compiler from
> optimizing away the memory access. This idiom is cryptic and duplicated
> across multiple test files.
>
> Following a suggestion from David[1], this patch refactors this
> common pattern into a FORCE_READ() macro
>
> [1] https://lore.kernel.org/lkml/4a3e0759-caa1-4cfa-bc3f-402593f1eee3@redhat.com/
>
> Signed-off-by: wang lian <lianux.mm@gmail.com>
> Reviewed-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
> ---
> tools/testing/selftests/mm/cow.c | 30 +++++++++----------
> tools/testing/selftests/mm/guard-regions.c | 7 -----
> tools/testing/selftests/mm/hugetlb-madvise.c | 5 +---
> tools/testing/selftests/mm/migration.c | 13 ++++----
> tools/testing/selftests/mm/pagemap_ioctl.c | 4 +--
> .../selftests/mm/split_huge_page_test.c | 4 +--
> tools/testing/selftests/mm/vm_util.h | 7 +++++
> 7 files changed, 31 insertions(+), 39 deletions(-)
Reviewed-by: Zi Yan <ziy@nvidia.com>
Best Regards,
Yan, Zi
next prev parent reply other threads:[~2025-07-18 15:11 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-07-17 13:18 [PATCH v2 RESEND 0/2] selftests/mm: reuse FORCE_READ to replace "asm volatile("" : "+r" (XXX));" and some cleanup wang lian
2025-07-17 13:18 ` [PATCH 1/2] selftests/mm: reuse FORCE_READ to replace "asm volatile("" : "+r" (XXX));" wang lian
2025-07-17 14:49 ` David Hildenbrand
2025-07-21 11:49 ` wang lian
2025-07-18 0:08 ` Wei Yang
2025-07-21 11:51 ` wang lian
2025-07-18 15:11 ` Zi Yan [this message]
2025-08-05 14:26 ` Zi Yan
2025-08-07 12:16 ` David Laight
2025-08-07 12:21 ` Zi Yan
2025-07-17 13:18 ` [PATCH 2/2] selftests/mm: guard-regions: Use SKIP() instead of ksft_exit_skip() wang lian
2025-07-17 14:17 ` Mark Brown
2025-07-18 0:13 ` Wei Yang
2025-07-18 15:11 ` Zi Yan
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