Re: [PATCH v4 0/2] fs, audit: Avoid excessive dput/dget in audit_context setup and reset paths

[Christian Brauner]

 On Sat, Feb 28, 2026 at 01:27:55PM -0500, Waiman Long wrote:
>  v4:
>   - Add ack and review tags
>   - Simplify put_fs_pwd_pool() in patch 1 as suggested by Paul Moore
> 
>  v3:
>   - https://lore.kernel.org/lkml/20260206201918.1988344-1-longman@xxxxxxxxxx/
> 
> When the audit subsystem is enabled, it can do a lot of get_fs_pwd()
> calls to get references to fs->pwd and then releasing those references
> back with path_put() later. That may cause a lot of spinlock contention
> on a single pwd's dentry lock because of the constant changes to the
> reference count when there are many processes on the same working
> directory actively doing open/close system calls. This can cause
> noticeable performance regresssion when compared with the case where
> the audit subsystem is turned off especially on systems with a lot of
> CPUs which is becoming more common these days.
> 
> This patch series aim to avoid this type of performance regression caused
> by audit by adding a new set of fs_struct helpers to reduce unncessary
> path_get() and path_put() calls and the audit code is modified to use
> these new helpers.

Tbh, the open-coding everywhere is really not very tasteful and makes me
not want to do this at all. Ideally we'd have a better mechanism that
avoids all this new spaghetti in various codepaths.

In it's current form I don't find it palatable. I added a few cleanups
on top that make it at least somewhat ok.