linux-kernel - Re: [PATCH] selftests/mm: run_vmtests.sh: Fix hugetlb mem size calculation

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Date: Wed, 3 Apr 2024 12:04:00 +0100
From: Ryan Roberts <ryan.roberts@....com>
To: peterx@...hat.com, linux-mm@...ck.org, linux-kernel@...r.kernel.org
Cc: Andrew Morton <akpm@...ux-foundation.org>,
 Muhammad Usama Anjum <usama.anjum@...labora.com>,
 David Hildenbrand <david@...hat.com>, Nico Pache <npache@...hat.com>,
 Muchun Song <muchun.song@...ux.dev>
Subject: Re: [PATCH] selftests/mm: run_vmtests.sh: Fix hugetlb mem size
 calculation

Hi Peter,

On 21/03/2024 21:50, peterx@...hat.com wrote:
> From: Peter Xu <peterx@...hat.com>
> 
> The script calculates a mininum required size of hugetlb memories, but
> it'll stop working with <1MB huge page sizes, reporting all zeros even if
> huge pages are available.
> 
> In reality, the calculation doesn't really need to be as comlicated either.
> Make it simpler and work for KB-level hugepages too.
> 
> Cc: Muhammad Usama Anjum <usama.anjum@...labora.com>
> Cc: David Hildenbrand <david@...hat.com>
> Cc: Nico Pache <npache@...hat.com>
> Cc: Muchun Song <muchun.song@...ux.dev>
> Signed-off-by: Peter Xu <peterx@...hat.com>
> ---
>  tools/testing/selftests/mm/run_vmtests.sh | 10 +++++++---
>  1 file changed, 7 insertions(+), 3 deletions(-)
> 
> diff --git a/tools/testing/selftests/mm/run_vmtests.sh b/tools/testing/selftests/mm/run_vmtests.sh
> index c2c542fe7b17..b1b78e45d613 100755
> --- a/tools/testing/selftests/mm/run_vmtests.sh
> +++ b/tools/testing/selftests/mm/run_vmtests.sh
> @@ -152,9 +152,13 @@ done < /proc/meminfo
>  # both of these requirements into account and attempt to increase
>  # number of huge pages available.
>  nr_cpus=$(nproc)
> -hpgsize_MB=$((hpgsize_KB / 1024))
> -half_ufd_size_MB=$((((nr_cpus * hpgsize_MB + 127) / 128) * 128))

Removing this has broken the uffd-stress "hugetlb" and "hugetlb-private" tests
(further down the file), which rely on $half_ufd_size_MB. Now that this is not
defined, they are called with too few params:


# # ---------------------------------
# # running ./uffd-stress hugetlb  32
# # ---------------------------------
# # ERROR: invalid MiB (errno=0, @uffd-stress.c:454)
# #
# # Usage: ./uffd-stress <test type> <MiB> <bounces>
# #
# # Supported <test type>: anon, hugetlb, hugetlb-private, shmem, shmem-private
# #
# # Examples:
# #
# # # Run anonymous memory test on 100MiB region with 99999 bounces:
# # ./uffd-stress anon 100 99999
# #
# # # Run share memory test on 1GiB region with 99 bounces:
# # ./uffd-stress shmem 1000 99
# #
# # # Run hugetlb memory test on 256MiB region with 50 bounces:
# # ./uffd-stress hugetlb 256 50
# #
# # # Run the same hugetlb test but using private file:
# # ./uffd-stress hugetlb-private 256 50
# #
# # # 10MiB-~6GiB 999 bounces anonymous test, continue forever unless an error
triggers
# # while ./uffd-stress anon $[RANDOM % 6000 + 10] 999; do true; done
# #
# # [FAIL]
# not ok 16 uffd-stress hugetlb 32 # exit=1
# # -----------------------------------------
# # running ./uffd-stress hugetlb-private  32
# # -----------------------------------------
# # ERROR: invalid MiB (errno=0, @uffd-stress.c:454)
# #
# # Usage: ./uffd-stress <test type> <MiB> <bounces>
# #
# # Supported <test type>: anon, hugetlb, hugetlb-private, shmem, shmem-private
# #
# # Examples:
# #
# # # Run anonymous memory test on 100MiB region with 99999 bounces:
# # ./uffd-stress anon 100 99999
# #
# # # Run share memory test on 1GiB region with 99 bounces:
# # ./uffd-stress shmem 1000 99
# #
# # # Run hugetlb memory test on 256MiB region with 50 bounces:
# # ./uffd-stress hugetlb 256 50
# #
# # # Run the same hugetlb test but using private file:
# # ./uffd-stress hugetlb-private 256 50
# #
# # # 10MiB-~6GiB 999 bounces anonymous test, continue forever unless an error
triggers
# # while ./uffd-stress anon $[RANDOM % 6000 + 10] 999; do true; done
# #
# # [FAIL]
# not ok 17 uffd-stress hugetlb-private 32 # exit=1


Thanks,
Ryan

> -needmem_KB=$((half_ufd_size_MB * 2 * 1024))
> +uffd_min_KB=$((hpgsize_KB * nr_cpus * 2))
> +hugetlb_min_KB=$((256 * 1024))
> +if [[ $uffd_min_KB -gt $hugetlb_min_KB ]]; then
> +	needmem_KB=$uffd_min_KB
> +else
> +	needmem_KB=$hugetlb_min_KB
> +fi
>  
>  # set proper nr_hugepages
>  if [ -n "$freepgs" ] && [ -n "$hpgsize_KB" ]; then