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

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