linux-kernel - Re: [PATCH] pid: reorder fields in pid

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Message-ID: <20260123-hoftheater-traufe-d81dc3c6c0c7@brauner>
Date: Fri, 23 Jan 2026 11:26:26 +0100
From: Christian Brauner <brauner@...nel.org>
To: Mateusz Guzik <mjguzik@...il.com>
Cc: Christian Brauner <brauner@...nel.org>,
	viro@...iv.linux.org.uk,
	jack@...e.cz,
	linux-kernel@...r.kernel.org,
	linux-fsdevel@...r.kernel.org
Subject: Re: [PATCH] pid: reorder fields in pid_namespace to reduce false sharing

On Tue, 20 Jan 2026 21:48:20 +0100, Mateusz Guzik wrote:
> alloc_pid() loads pid_cachep, level and pid_max prior to taking the
> lock.
> 
> It dirties idr and pid_allocated with the lock.
> 
> Some of these fields share the cacheline as is, split them up.
> 
> [...]

Applied to the kernel-7.0.misc branch of the vfs/vfs.git tree.
Patches in the kernel-7.0.misc branch should appear in linux-next soon.

Please report any outstanding bugs that were missed during review in a
new review to the original patch series allowing us to drop it.

It's encouraged to provide Acked-bys and Reviewed-bys even though the
patch has now been applied. If possible patch trailers will be updated.

Note that commit hashes shown below are subject to change due to rebase,
trailer updates or similar. If in doubt, please check the listed branch.

tree:   https://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs.git
branch: kernel-7.0.misc

[1/1] pid: reorder fields in pid_namespace to reduce false sharing
      https://git.kernel.org/vfs/vfs/c/e7d0463629d1