On 12/21/25 7:26 AM, Li Wang wrote:
charge_reserved_hugetlb.sh mounts a hugetlbfs instance at /mnt/huge with a fixed size of 256M. On systems with large base hugepages (e.g. 512MB), this is smaller than a single hugepage, so the hugetlbfs mount ends up with zero capacity (often visible as size=0 in mount output).As a result, write_to_hugetlbfs fails with ENOMEM and the test can hang waiting for progress. --- Error log --- # uname -r 6.12.0-xxx.el10.aarch64+64k #./charge_reserved_hugetlb.sh -cgroup-v2 # ----------------------------------------- ... # nr hugepages = 10 # writing cgroup limit: 5368709120 # writing reseravation limit: 5368709120 ... # write_to_hugetlbfs: Error mapping the file: Cannot allocate memory # Waiting for hugetlb memory reservation to reach size 2684354560. # 0 # Waiting for hugetlb memory reservation to reach size 2684354560. # 0 ... # mount |grep /mnt/huge none on /mnt/huge type hugetlbfs (rw,relatime,seclabel,pagesize=512M,size=0) # grep -i huge /proc/meminfo ... HugePages_Total: 10 HugePages_Free: 10 HugePages_Rsvd: 0 HugePages_Surp: 0 Hugepagesize: 524288 kB Hugetlb: 5242880 kB Drop the mount args with 'size=256M', so the filesystem capacity is sufficient regardless of HugeTLB page size. Fixes: 29750f71a9 ("hugetlb_cgroup: add hugetlb_cgroup reservation tests") Signed-off-by: Li Wang <[email protected]> Cc: David Hildenbrand <[email protected]> Cc: Mark Brown <[email protected]> Cc: Shuah Khan <[email protected]> Cc: Waiman Long <[email protected]> --- tools/testing/selftests/mm/charge_reserved_hugetlb.sh | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/tools/testing/selftests/mm/charge_reserved_hugetlb.sh b/tools/testing/selftests/mm/charge_reserved_hugetlb.sh index e1fe16bcbbe8..fa6713892d82 100755 --- a/tools/testing/selftests/mm/charge_reserved_hugetlb.sh +++ b/tools/testing/selftests/mm/charge_reserved_hugetlb.sh @@ -290,7 +290,7 @@ function run_test() { setup_cgroup "hugetlb_cgroup_test" "$cgroup_limit" "$reservation_limit"mkdir -p /mnt/huge- mount -t hugetlbfs -o pagesize=${MB}M,size=256M none /mnt/huge + mount -t hugetlbfs -o pagesize=${MB}M none /mnt/hugewrite_hugetlbfs_and_get_usage "hugetlb_cgroup_test" "$size" "$populate" \"$write" "/mnt/huge/test" "$method" "$private" "$expect_failure" \ @@ -344,7 +344,7 @@ function run_multiple_cgroup_test() { setup_cgroup "hugetlb_cgroup_test2" "$cgroup_limit2" "$reservation_limit2"mkdir -p /mnt/huge- mount -t hugetlbfs -o pagesize=${MB}M,size=256M none /mnt/huge + mount -t hugetlbfs -o pagesize=${MB}M none /mnt/hugewrite_hugetlbfs_and_get_usage "hugetlb_cgroup_test1" "$size1" \"$populate1" "$write1" "/mnt/huge/test1" "$method" "$private" \
Acked-by: Waiman Long <[email protected]>
