linux-kernel - Re: [PATCH v3 2/3] selftests/mm/charge_reserved

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <53e302a7-1c78-4b76-87e8-1cc10c76535d@kernel.org>
Date: Mon, 22 Dec 2025 11:01:17 +0100
From: "David Hildenbrand (Red Hat)" <david@...nel.org>
To: Li Wang <liwang@...hat.com>, akpm@...ux-foundation.org,
 linux-kselftest@...r.kernel.org, linux-kernel@...r.kernel.org,
 linux-mm@...ck.org
Cc: Mark Brown <broonie@...nel.org>, Shuah Khan <shuah@...nel.org>,
 Waiman Long <longman@...hat.com>
Subject: Re: [PATCH v3 2/3] selftests/mm/charge_reserved_hugetlb: drop mount
 size for hugetlbfs

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@...nel.org>

-- 
Cheers

David