linux-kernel - Re: [PATCH v16 8/9] task: rust: rework how current is accessed

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] [day] [month] [year] [list]

Message-ID: <159796e5-bc36-4735-beae-b849c157543c@nvidia.com>
Date: Thu, 8 May 2025 13:25:27 -0700
From: John Hubbard <jhubbard@...dia.com>
To: Boqun Feng <boqun.feng@...il.com>, Alice Ryhl <aliceryhl@...gle.com>
Cc: Miguel Ojeda <ojeda@...nel.org>, Matthew Wilcox <willy@...radead.org>,
 Lorenzo Stoakes <lorenzo.stoakes@...cle.com>,
 Vlastimil Babka <vbabka@...e.cz>, "Liam R. Howlett"
 <Liam.Howlett@...cle.com>, Andrew Morton <akpm@...ux-foundation.org>,
 Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
 Arnd Bergmann <arnd@...db.de>, Jann Horn <jannh@...gle.com>,
 Suren Baghdasaryan <surenb@...gle.com>, Alex Gaynor <alex.gaynor@...il.com>,
 Gary Guo <gary@...yguo.net>, Björn Roy Baron
 <bjorn3_gh@...tonmail.com>, Benno Lossin <benno.lossin@...ton.me>,
 Andreas Hindborg <a.hindborg@...nel.org>, Trevor Gross <tmgross@...ch.edu>,
 linux-kernel@...r.kernel.org, linux-mm@...ck.org,
 rust-for-linux@...r.kernel.org
Subject: Re: [PATCH v16 8/9] task: rust: rework how current is accessed

On 5/7/25 9:55 AM, Boqun Feng wrote:
> On Wed, May 07, 2025 at 09:46:23AM -0700, Boqun Feng wrote:
>> On Wed, May 07, 2025 at 09:06:01AM -0700, Boqun Feng wrote:
>> [...]
>> Hmm.. this alone won't be enough, because miscdevice also uses mm. Maybe
>> you could most of mm defined even when CONFIG_MMU=n but keep
>> MmWithUserAsync only available when CONFIG_MMU=y?
>>
> 
> Something like this, probably? But your choice ;-) Make CONFIG_RUST
> select CONFIG_MMU is fine but the question is who is going to unselect
> that at when?
> 

In case it helps for the future: you should never select CONFIG_MMU.
You can depend on CONFIG_MMU, but forcibly selecting it is wrong,
because MMU support is a much broader system config decision than
CONFIG_RUST, and must not be auto-selected.

Also, some systems do not even have an MMU, and therefore should 
not have CONFIG_MMU nor CONFIG_RUST forcibly selected.

thanks,
John