linux-kernel - Re: [PATCH] selftests/mm: run_vmtests.sh: fix half_ufd_size

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Message-ID: <Z7XqLQmmkDjWNM_5@x1.local>
Date: Wed, 19 Feb 2025 09:26:53 -0500
From: Peter Xu <peterx@...hat.com>
To: Rafael Aquini <aquini@...hat.com>
Cc: linux-kselftest@...r.kernel.org, linux-mm@...ck.org,
	linux-kernel@...r.kernel.org, David Hildenbrand <david@...hat.com>,
	Shuah Khan <shuah@...nel.org>
Subject: Re: [PATCH] selftests/mm: run_vmtests.sh: fix half_ufd_size_MB
 calculation

On Tue, Feb 18, 2025 at 02:22:51PM -0500, Rafael Aquini wrote:
> From: Rafael Aquini <raquini@...hat.com>
> 
> We noticed that uffd-stress test was always failing to run when invoked
> for the hugetlb profiles on x86_64 systems with a processor count of 64
> or bigger:
>   ...
>   # ------------------------------------
>   # running ./uffd-stress hugetlb 128 32
>   # ------------------------------------
>   # ERROR: invalid MiB (errno=9, @uffd-stress.c:459)
>   ...
>   # [FAIL]
>   not ok 3 uffd-stress hugetlb 128 32 # exit=1
>   ...
> 
> The problem boils down to how run_vmtests.sh (mis)calculates the size
> of the region it feeds to uffd-stress. The latter expects to see an
> amount of MiB while the former is just giving out the number of free
> hugepages halved down. This measurement discrepancy ends up violating
> uffd-stress' assertion on number of hugetlb pages allocated per CPU,
> causing it to bail out with the error above.
> 
> This commit fixes that issue by adjusting run_vmtests.sh's half_ufd_size_MB
> calculation so it properly renders the region size in MiB, as expected,
> while maintaining all of its original constraints in place.
> 
> Fixes: 2e47a445d7b3 ("selftests/mm: run_vmtests.sh: fix hugetlb mem size calculation")
> Signed-off-by: Rafael Aquini <raquini@...hat.com>

Oops.. thanks!

Reviewed-by: Peter Xu <peterx@...hat.com>

-- 
Peter Xu