Re: [PATCH v3 2/3] selftests/mm/charge_reserved_hugetlb: drop mount size for hugetlbfs

["David Hildenbrand (Red Hat)" <david@kernel.org>]

On 12/21/25 13:26, 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")

Likely Andrew should add a CC of stable

Acked-by: David Hildenbrand (Red Hat) <david@kernel.org>

-- 
Cheers

David