linux-kernel - Re: [PATCH v2 3/3] selftests/mm/charge_reserved_hugetlb: fix hugetlbfs mount size for large hugepages

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: <30a75bb5-7edd-42b1-9a94-8ffe017bdb0b@kernel.org>
Date: Sun, 21 Dec 2025 10:49:18 +0100
From: "David Hildenbrand (Red Hat)" <david@...nel.org>
To: Li Wang <liwang@...hat.com>
Cc: akpm@...ux-foundation.org, linux-kselftest@...r.kernel.org,
 linux-kernel@...r.kernel.org, linux-mm@...ck.org,
 Mark Brown <broonie@...nel.org>, Shuah Khan <shuah@...nel.org>,
 Waiman Long <longman@...hat.com>
Subject: Re: [PATCH v2 3/3] selftests/mm/charge_reserved_hugetlb: fix
 hugetlbfs mount size for large hugepages

On 12/21/25 10:44, Li Wang wrote:
> David Hildenbrand (Red Hat) <david@...nel.org> wrote:
>> On 12/21/25 09:58, 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 effectively 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.
>>
>> I'm curious, what's the history of using "256MB" in the first place (or
>> specifying any size?).
> 
> Seems the script initializes it with "256MB" from:
> 
> commit 29750f71a9b4cfae57cdddfbd8ca287eddca5503
> Author: Mina Almasry <almasrymina@...gle.com>
> Date:   Wed Apr 1 21:11:38 2020 -0700
> 
>      hugetlb_cgroup: add hugetlb_cgroup reservation tests

What would happen if we don't specify a size at all?

-- 
Cheers

David