Re: [PATCH] selftests/mm: use volatile keyword to not optimize mmap read variable

[Zi Yan <ziy@nvidia.com>]

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On 6 Jun 2024, at 6:58, Pankaj Raghav (Samsung) wrote:

> From: Pankaj Raghav <p.raghav@samsung.com>
>
> create_pagecache_thp_and_fd() in split_huge_page_test.c used the
> variable dummy to perform mmap read.
>
> However, this test was skipped even on XFS which has large folio
> support. The issue was compiler (gcc 13.2.0) was optimizing out the
> dummy variable, therefore, not creating huge page in the page cache.
>
> Add volatile keyword to force compiler not to optimize out the loop
> where we read from the mmaped addr.
>
> Signed-off-by: Pankaj Raghav <p.raghav@samsung.com>
> ---
>  tools/testing/selftests/mm/split_huge_page_test.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>

Acked-by: Zi Yan <ziy@nvidia.com>

Best Regards,
Yan, Zi

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