On Wed, Aug 27, 2025 at 7:41 PM David Hildenbrand david@redhat.com wrote:
On 27.08.25 09:52, Chunyu Hu wrote:
The nr_hugepgs variable is used to keep the original nr_hugepages at the hugepage setup step at test beginning. After userfaultfd test, a cleaup is executed, both /sys/kernel/mm/hugepages/hugepages-*/nr_hugepages and /proc/sys//vm/nr_hugepages are reset to 'original' value before userfaultfd test starts.
Issue here is the value used to restore /proc/sys/vm/nr_hugepages is nr_hugepgs which is the initial value before the vm_runtests.sh runs, not the value before userfaultfd test starts. 'va_high_addr_swith.sh' tests runs after that will possibly see no hugepages available for test, and got EINVAL when mmap(HUGETLB), making the result invalid.
And before pkey tests, nr_hugepgs is changed to be used as a temp variable to save nr_hugepages before pkey test, and restore it after pkey tests finish. The original nr_hugepages value is not tracked anymore, so no way to restore it after all tests finish.
Add a new variable nr_hugepgs_origin to save the original nr_hugepages, and and restore it to nr_hugepages after all tests finish. And change to use the nr_hugepgs variable to save the /proc/sys/vm/nr_hugeages after hugepage setup, it's also the value before userfaultfd test starts, and the correct value to be restored after userfaultfd finishes. The va_high_addr_switch.sh broken will be resolved.
Signed-off-by: Chunyu Hu chuhu@redhat.com
tools/testing/selftests/mm/run_vmtests.sh | 9 +++++++-- 1 file changed, 7 insertions(+), 2 deletions(-)
diff --git a/tools/testing/selftests/mm/run_vmtests.sh b/tools/testing/selftests/mm/run_vmtests.sh index 471e539d82b8..f1a7ad3ec6a7 100755 --- a/tools/testing/selftests/mm/run_vmtests.sh +++ b/tools/testing/selftests/mm/run_vmtests.sh @@ -172,13 +172,13 @@ fi
# set proper nr_hugepages if [ -n "$freepgs" ] && [ -n "$hpgsize_KB" ]; then
nr_hugepgs=$(cat /proc/sys/vm/nr_hugepages)
nr_hugepgs_origin=$(cat /proc/sys/vm/nr_hugepages)I'd call this "orig_nr_hugepgs".
Hi David,
Thank you for your review and valuable feedback. I will rename it with a v2 and resend the two patches. Do you have suggestions on patch 2?
But it's a shame that the naming is then out of sync with nr_size_hugepgs?
nr_size_hugepgs is for uffd-wp-mremap, the test need all sizes hugepages, it's used to save and restore the nr_hugepagees of all sizes of hugepages, it's a test case setup, not like nr_hugepgs which is a global/general setup. They are not the same kind, maybe they don't need to be aligned...
needpgs=$((needmem_KB / hpgsize_KB)) tries=2 while [ "$tries" -gt 0 ] && [ "$freepgs" -lt "$needpgs" ]; do lackpgs=$((needpgs - freepgs)) echo 3 > /proc/sys/vm/drop_caches
if ! echo $((lackpgs + nr_hugepgs)) > /proc/sys/vm/nr_hugepages; then
if ! echo $((lackpgs + nr_hugepgs_origin)) > /proc/sys/vm/nr_hugepages; then echo "Please run this test as root" exit $ksft_skip fi@@ -189,6 +189,7 @@ if [ -n "$freepgs" ] && [ -n "$hpgsize_KB" ]; then done < /proc/meminfo tries=$((tries - 1)) done
nr_hugepgs=$(cat /proc/sys/vm/nr_hugepages) if [ "$freepgs" -lt "$needpgs" ]; then printf "Not enough huge pages available (%d < %d)\n" \ "$freepgs" "$needpgs"@@ -532,6 +533,10 @@ CATEGORY="page_frag" run_test ./test_page_frag.sh aligned
CATEGORY="page_frag" run_test ./test_page_frag.sh nonaligned
+if [ "${HAVE_HUGEPAGES}" = 1 ]; then
echo "$nr_hugepgs_origin" > /proc/sys/vm/nr_hugepages+fi
FWIW, I think the tests should maybe be doing that (save+configure+restore) themselves, like we do with THP settings through.
thp_save_settings() thp_write_settings()
and friends.
This is not really something run_vmtests.sh should bother with.
A bigger rework, though ...
Totally agree, with the c interface to do that is better. then the vm_runtest.sh would be clean. It's a bigger rework outside of this topic...
-- Cheers
David / dhildenb
-- ---- Thanks, Chunyu Hu