linux-kernel - Re: [PATCH v2 2/3] mm: secretmem: convert to .mmap

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Message-ID: <5c5ccea9-3ce4-40c5-94b4-796d4bc1f533@suse.cz>
Date: Mon, 12 May 2025 15:41:08 +0200
From: Vlastimil Babka <vbabka@...e.cz>
To: Lorenzo Stoakes <lorenzo.stoakes@...cle.com>,
 Andrew Morton <akpm@...ux-foundation.org>
Cc: David Hildenbrand <david@...hat.com>,
 "Liam R . Howlett" <Liam.Howlett@...cle.com>, Mike Rapoport
 <rppt@...nel.org>, Suren Baghdasaryan <surenb@...gle.com>,
 Michal Hocko <mhocko@...e.com>, Jann Horn <jannh@...gle.com>,
 Pedro Falcato <pfalcato@...e.de>, linux-fsdevel@...r.kernel.org,
 linux-kernel@...r.kernel.org, linux-mm@...ck.org,
 Alexander Viro <viro@...iv.linux.org.uk>,
 Christian Brauner <brauner@...nel.org>, Jan Kara <jack@...e.cz>,
 Matthew Wilcox <willy@...radead.org>
Subject: Re: [PATCH v2 2/3] mm: secretmem: convert to .mmap_prepare() hook

On 5/9/25 14:13, Lorenzo Stoakes wrote:
> Secretmem has a simple .mmap() hook which is easily converted to the new
> .mmap_prepare() callback.
> 
> Importantly, it's a rare instance of an driver that manipulates a VMA which
> is mergeable (that is, not a VM_SPECIAL mapping) while also adjusting VMA
> flags which may adjust mergeability, meaning the retry merge logic might
> impact whether or not the VMA is merged.
> 
> By using .mmap_prepare() there's no longer any need to retry the merge
> later as we can simply set the correct flags from the start.
> 
> This change therefore allows us to remove the retry merge logic in a
> subsequent commit.
> 
> Signed-off-by: Lorenzo Stoakes <lorenzo.stoakes@...cle.com>
> Acked-by: Mike Rapoport (Microsoft) <rppt@...nel.org>
> Reviewed-by: David Hildenbrand <david@...hat.com>

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