The patch titled Subject: selftests/mm: run_vmtests.sh: fix half_ufd_size_MB calculation has been added to the -mm mm-hotfixes-unstable branch. Its filename is selftests-mm-run_vmtestssh-fix-half_ufd_size_mb-calculation.patch
This patch will shortly appear at https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches...
This patch will later appear in the mm-hotfixes-unstable branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
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------------------------------------------------------ From: Rafael Aquini raquini@redhat.com Subject: selftests/mm: run_vmtests.sh: fix half_ufd_size_MB calculation Date: Tue, 18 Feb 2025 14:22:51 -0500
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.
Link: https://lkml.kernel.org/r/20250218192251.53243-1-aquini@redhat.com Fixes: 2e47a445d7b3 ("selftests/mm: run_vmtests.sh: fix hugetlb mem size calculation") Signed-off-by: Rafael Aquini raquini@redhat.com Reviewed-by: David Hildenbrand david@redhat.com Reviewed-by: Peter Xu peterx@redhat.com Cc: Shuah Khan shuah@kernel.org Cc: stable@vger.kernel.org Signed-off-by: Andrew Morton akpm@linux-foundation.org ---
tools/testing/selftests/mm/run_vmtests.sh | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-)
--- a/tools/testing/selftests/mm/run_vmtests.sh~selftests-mm-run_vmtestssh-fix-half_ufd_size_mb-calculation +++ a/tools/testing/selftests/mm/run_vmtests.sh @@ -304,7 +304,9 @@ uffd_stress_bin=./uffd-stress CATEGORY="userfaultfd" run_test ${uffd_stress_bin} anon 20 16 # Hugetlb tests require source and destination huge pages. Pass in half # the size of the free pages we have, which is used for *each*. -half_ufd_size_MB=$((freepgs / 2)) +# uffd-stress expects a region expressed in MiB, so we adjust +# half_ufd_size_MB accordingly. +half_ufd_size_MB=$(((freepgs * hpgsize_KB) / 1024 / 2)) CATEGORY="userfaultfd" run_test ${uffd_stress_bin} hugetlb "$half_ufd_size_MB" 32 CATEGORY="userfaultfd" run_test ${uffd_stress_bin} hugetlb-private "$half_ufd_size_MB" 32 CATEGORY="userfaultfd" run_test ${uffd_stress_bin} shmem 20 16 _
Patches currently in -mm which might be from raquini@redhat.com are
selftests-mm-run_vmtestssh-fix-half_ufd_size_mb-calculation.patch