linux-kernel - Re: [PATCH v1] mm: Consistently use current->mm in mm_get_unmapped

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: <d398bcf6-30f2-44a8-9721-1c4c763951b6@redhat.com>
Date: Mon, 6 Oct 2025 10:20:03 +0200
From: David Hildenbrand <david@...hat.com>
To: Ryan Roberts <ryan.roberts@....com>,
 Andrew Morton <akpm@...ux-foundation.org>,
 Lorenzo Stoakes <lorenzo.stoakes@...cle.com>,
 "Liam R. Howlett" <Liam.Howlett@...cle.com>, Vlastimil Babka
 <vbabka@...e.cz>, Mike Rapoport <rppt@...nel.org>,
 Suren Baghdasaryan <surenb@...gle.com>, Michal Hocko <mhocko@...e.com>
Cc: linux-mm@...ck.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v1] mm: Consistently use current->mm in
 mm_get_unmapped_area()

On 03.10.25 17:53, Ryan Roberts wrote:
> mm_get_unmapped_area() is a wrapper around arch_get_unmapped_area() /
> arch_get_unmapped_area_topdown(), both of which search current->mm for
> some free space. Neither take an mm_struct - they implicitly operate on
> current->mm.
> 
> But the wrapper takes an mm_struct and uses it to decide whether to
> search bottom up or top down. All callers pass in current->mm for this,
> so everything is working consistently. But it feels like an accident
> waiting to happen; eventually someone will call that function with a
> different mm, expecting to find free space in it, but what gets returned
> is free space in the current mm.
> 
> So let's simplify by removing the parameter and have the wrapper use
> current->mm to decide which end to start at. Now everything is
> consistent and self-documenting.
> 
> Signed-off-by: Ryan Roberts <ryan.roberts@....com>

Yeah, that looks better to me.

Acked-by: David Hildenbrand <david@...hat.com>

-- 
Cheers

David / dhildenb