linux-kernel - Re: [PATCH v3 2/4] mm: abstract initial stack setup to mm subsystem

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Message-ID: <d1fbd13b-b2a4-4725-9676-7c7081230fb2@suse.cz>
Date: Tue, 29 Apr 2025 09:04:47 +0200
From: Vlastimil Babka <vbabka@...e.cz>
To: Lorenzo Stoakes <lorenzo.stoakes@...cle.com>,
 Andrew Morton <akpm@...ux-foundation.org>
Cc: "Liam R . Howlett" <Liam.Howlett@...cle.com>, Jann Horn
 <jannh@...gle.com>, Pedro Falcato <pfalcato@...e.de>,
 David Hildenbrand <david@...hat.com>, Kees Cook <kees@...nel.org>,
 Alexander Viro <viro@...iv.linux.org.uk>,
 Christian Brauner <brauner@...nel.org>, Jan Kara <jack@...e.cz>,
 Suren Baghdasaryan <surenb@...gle.com>, linux-mm@...ck.org,
 linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3 2/4] mm: abstract initial stack setup to mm subsystem

On 4/28/25 17:28, Lorenzo Stoakes wrote:
> There are peculiarities within the kernel where what is very clearly mm
> code is performed elsewhere arbitrarily.
> 
> This violates separation of concerns and makes it harder to refactor code
> to make changes to how fundamental initialisation and operation of mm logic
> is performed.
> 
> One such case is the creation of the VMA containing the initial stack upon
> execve()'ing a new process. This is currently performed in __bprm_mm_init()
> in fs/exec.c.
> 
> Abstract this operation to create_init_stack_vma(). This allows us to limit
> use of vma allocation and free code to fork and mm only.
> 
> We previously did the same for the step at which we relocate the initial
> stack VMA downwards via relocate_vma_down(), now we move the initial VMA
> establishment too.
> 
> Take the opportunity to also move insert_vm_struct() to mm/vma.c as it's no
> longer needed anywhere outside of mm.
> 
> Signed-off-by: Lorenzo Stoakes <lorenzo.stoakes@...cle.com>
> Acked-by: David Hildenbrand <david@...hat.com>
> Reviewed-by: Suren Baghdasaryan <surenb@...gle.com>

Reviewed-by: Vlastimil Babka <vbabka@...e.cz>