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Date: Mon, 29 Jan 2024 17:47:32 -0500
From: Steven Rostedt <rostedt@goodmis.org>
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: kernel test robot <oliver.sang@intel.com>, oe-lkp@lists.linux.dev,
 lkp@intel.com, linux-kernel@vger.kernel.org, Masami Hiramatsu
 <mhiramat@kernel.org>, Mark Rutland <mark.rutland@arm.com>, Mathieu
 Desnoyers <mathieu.desnoyers@efficios.com>, Christian Brauner
 <brauner@kernel.org>, Al Viro <viro@zeniv.linux.org.uk>, Ajay Kaher
 <ajay.kaher@broadcom.com>, linux-trace-kernel@vger.kernel.org
Subject: Re: [linus:master] [eventfs] 852e46e239:
 BUG:unable_to_handle_page_fault_for_address
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On Mon, 29 Jan 2024 14:35:37 -0800
Linus Torvalds <torvalds@linux-foundation.org> wrote:

> And I hope there aren't any other stupid things I missed like that.

Well the preliminary tests pass with this added to your patch:

diff --git a/fs/tracefs/event_inode.c b/fs/tracefs/event_inode.c
index cd6de3244442..ad11063bdd53 100644
--- a/fs/tracefs/event_inode.c
+++ b/fs/tracefs/event_inode.c
@@ -230,7 +230,6 @@ static struct eventfs_inode *eventfs_find_events(struct dentry *dentry)
 {
 	struct eventfs_inode *ei;
 
-	mutex_lock(&eventfs_mutex);
 	do {
 		// The parent is stable because we do not do renames
 		dentry = dentry->d_parent;
@@ -247,7 +246,6 @@ static struct eventfs_inode *eventfs_find_events(struct dentry *dentry)
 		}
 		// Walk upwards until you find the events inode
 	} while (!ei->is_events);
-	mutex_unlock(&eventfs_mutex);
 
 	update_top_events_attr(ei, dentry->d_sb);
 
@@ -324,7 +322,7 @@ static struct dentry *lookup_file(struct dentry *dentry,
 	ti->flags = TRACEFS_EVENT_INODE;
 	ti->private = NULL;			// Directories have 'ei', files not
 
-	d_instantiate(dentry, inode);
+	d_add(dentry, inode);
 	fsnotify_create(dentry->d_parent->d_inode, dentry);
 	return eventfs_end_creating(dentry);
 };
@@ -365,7 +363,7 @@ static struct dentry *lookup_dir_entry(struct dentry *dentry,
         ei->dentry = dentry;	// Remove me!
 
 	inc_nlink(inode);
-	d_instantiate(dentry, inode);
+	d_add(dentry, inode);
 	inc_nlink(dentry->d_parent->d_inode);
 	fsnotify_mkdir(dentry->d_parent->d_inode, dentry);
 	return eventfs_end_creating(dentry);

-- Steve