Re: [linus:master] [eventfs] 852e46e239: BUG:unable_to_handle_page_fault_for_address

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
Date: Wed, 31 Jan 2024 11:13:58 -0500	[thread overview]
Message-ID: <20240131111358.5506645a@gandalf.local.home> (raw)
In-Reply-To: <20240131105847.3e9afcb8@gandalf.local.home>

On Wed, 31 Jan 2024 10:58:47 -0500
Steven Rostedt <rostedt@goodmis.org> wrote:

> @@ -788,6 +717,7 @@ static void init_once(void *foo)
>  {
>  	struct tracefs_inode *ti = (struct tracefs_inode *) foo;
>  
> +	memset(ti, 0, sizeof(*ti));
>  	inode_init_once(&ti->vfs_inode);
>  }
>  

Note, that inode_init_once() also does a memset on the entire inode, so the
initial memset is redundant on the inode portion. But I didn't think it was
really worth the time to complicate the code by optimizing it. I guess if I
changed the structure to:

 struct tracefs_inode {
+	struct inode            vfs_inode;
	unsigned long           flags;
	void                    *private;
-	struct inode            vfs_inode;
 };

I could have it do:

	memset_after(ti, 0, vfs_inode);

But this can be done as a separate clean up and doesn't need to be done now.

-- Steve