linux-kernel - Re: [PATCH v1 11/14] futex: Implement FUTEX2

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: <f0df62e6-c7af-89a1-89ee-4ee55fff00c4@gentwo.org>
Date: Mon, 28 Oct 2024 15:32:47 -0700 (PDT)
From: "Christoph Lameter (Ampere)" <cl@...two.org>
To: Peter Zijlstra <peterz@...radead.org>
cc: tglx@...utronix.de, axboe@...nel.dk, linux-kernel@...r.kernel.org, 
    mingo@...hat.com, dvhart@...radead.org, dave@...olabs.net, 
    andrealmeid@...lia.com, Andrew Morton <akpm@...ux-foundation.org>, 
    urezki@...il.com, hch@...radead.org, lstoakes@...il.com, 
    Arnd Bergmann <arnd@...db.de>, linux-api@...r.kernel.org, 
    linux-mm@...ck.org, linux-arch@...r.kernel.org, malteskarupke@....de
Subject: Re: [PATCH v1 11/14] futex: Implement FUTEX2_NUMA

On Sat, 26 Oct 2024, Peter Zijlstra wrote:

> I'll look into the per task thing, which I'm hoping means per-process.
> We need something that is mm wide consistent.

Each thread can modify its policy and that is used f.e. to control memory
allocations for syscalls. For example a thread wants to allocate kernel
metadata on a specific node then the policy would be set to that node.
Syscall is done and then the tasks resets the policy to the default.

mm wide memory policies are set at an VMA level and are associated with
addresses.

> But since futexes play in the address space, I was really rather
> thinking we ought to use the vma policy.

If they are associated with an address then you can use the address space
policy.