linux-kernel - Re: [PATCH AUTOSEL 6.14 26/39] fs/buffer: split locking for pagecache lookups

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: <aBFzPSBJAgOuCMnr@bombadil.infradead.org>
Date: Tue, 29 Apr 2025 17:47:57 -0700
From: Luis Chamberlain <mcgrof@...nel.org>
To: Sasha Levin <sashal@...nel.org>
Cc: linux-kernel@...r.kernel.org, stable@...r.kernel.org,
	Davidlohr Bueso <dave@...olabs.net>, Jan Kara <jack@...e.cz>,
	kdevops@...ts.linux.dev, Christian Brauner <brauner@...nel.org>,
	viro@...iv.linux.org.uk, linux-fsdevel@...r.kernel.org
Subject: Re: [PATCH AUTOSEL 6.14 26/39] fs/buffer: split locking for
 pagecache lookups

On Tue, Apr 29, 2025 at 07:49:53PM -0400, Sasha Levin wrote:
> From: Davidlohr Bueso <dave@...olabs.net>
> 
> [ Upstream commit 7ffe3de53a885dbb5836541c2178bd07d1bad7df ]
> 
> Callers of __find_get_block() may or may not allow for blocking
> semantics, and is currently assumed that it will not. Layout
> two paths based on this. The the private_lock scheme will
> continued to be used for atomic contexts. Otherwise take the
> folio lock instead, which protects the buffers, such as
> vs migration and try_to_free_buffers().
> 
> Per the "hack idea", the latter can alleviate contention on
> the private_lock for bdev mappings. For reasons of determinism
> and avoid making bugs hard to reproduce, the trylocking is not
> attempted.
> 
> No change in semantics. All lookup users still take the spinlock.

This is pushing it. I would not expect this to go to stable. At all.

BTW you had mentioned the code for auto-sel would be published a while
ago, is it available anywhere?

  Luis