Re: [PATCH v2] audit: Avoid excessive dput/dget in audit_context setup and reset paths

From: Waiman Long

Date: Tue Feb 03 2026 - 15:34:28 EST

On 2/3/26 3:05 PM, Al Viro wrote:
On Tue, Feb 03, 2026 at 02:44:33PM -0500, Waiman Long wrote:

diff --git a/kernel/audit.h b/kernel/audit.h
index 7c401729e21b..03f3539b10e7 100644
--- a/kernel/audit.h
+++ b/kernel/audit.h
@@ -133,6 +133,13 @@ struct audit_context {
int name_count; /* total records in names_list */
struct list_head names_list; /* struct audit_names->list anchor */
char *filterkey; /* key for rule that triggered record */
+ /*
+ * pwd_reset is set if audit_free_names() has been called from
+ * audit_reset_context() to reset pwd, but pwd is still holding dentry
+ * and mount references to be used in later audit action without
+ * the need to reacqure the references again.
That's a delicate way to say "we have mounts stuck busy inexplicably for userland"...

Generally a chdir(2) away from something immediately followed by umount(2)
is _not_ expected to leave you with -EBUSY when nobody else has been doing
anything with the mount in question.

That is actually a concern that I have at the back of my mind. I can modify the patch to cache only the dentry and do get/put the mount every time which is much cheaper as it is a percpu counter.  In that way, a chdir(2) followed by a umount(2) shouldn't cause a -EBUSY. Right?

Cheers,
Longman