linux-kernel - Re: [PATCH v4 7/7] selftests: prctl: introduce tests for disabling THPs except for madvise

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: <bac33bcc-8a01-445d-bc42-29dabbdd1d3f@redhat.com>
Date: Wed, 13 Aug 2025 18:24:11 +0200
From: David Hildenbrand <david@...hat.com>
To: Lorenzo Stoakes <lorenzo.stoakes@...cle.com>,
 Usama Arif <usamaarif642@...il.com>
Cc: Andrew Morton <akpm@...ux-foundation.org>, linux-mm@...ck.org,
 linux-fsdevel@...r.kernel.org, corbet@....net, rppt@...nel.org,
 surenb@...gle.com, mhocko@...e.com, hannes@...xchg.org, baohua@...nel.org,
 shakeel.butt@...ux.dev, riel@...riel.com, ziy@...dia.com,
 laoar.shao@...il.com, dev.jain@....com, baolin.wang@...ux.alibaba.com,
 npache@...hat.com, Liam.Howlett@...cle.com, ryan.roberts@....com,
 vbabka@...e.cz, jannh@...gle.com, Arnd Bergmann <arnd@...db.de>,
 sj@...nel.org, linux-kernel@...r.kernel.org, linux-doc@...r.kernel.org,
 kernel-team@...a.com
Subject: Re: [PATCH v4 7/7] selftests: prctl: introduce tests for disabling
 THPs except for madvise

>> +
>> +FIXTURE_SETUP(prctl_thp_disable_except_madvise)
>> +{
>> +	if (!thp_available())
>> +		SKIP(return, "Transparent Hugepages not available\n");
>> +
>> +	self->pmdsize = read_pmd_pagesize();
>> +	if (!self->pmdsize)
>> +		SKIP(return, "Unable to read PMD size\n");
>> +
>> +	if (prctl(PR_SET_THP_DISABLE, 1, PR_THP_DISABLE_EXCEPT_ADVISED, NULL, NULL))
>> +		SKIP(return, "Unable to set PR_THP_DISABLE_EXCEPT_ADVISED\n");
> 
> This should be a test fail I think, as the only ways this could fail are
> invalid flags, or failure to obtain an mmap write lock.

Running a kernel that does not support it?

We could check the errno to distinguish I guess.

-- 
Cheers,

David / dhildenb