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

From: Linus Torvalds <torvalds@linux-foundation.org>
To: Steven Rostedt <rostedt@goodmis.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: Tue, 30 Jan 2024 08:51:25 -0800	[thread overview]
Message-ID: <CAHk-=whe_qeQVrz9=pVjCNVva8+OOJjmrpCj5CiHW3QStUf+6w@mail.gmail.com> (raw)
In-Reply-To: <20240130093942.56206ff1@gandalf.local.home>

On Tue, 30 Jan 2024 at 06:39, Steven Rostedt <rostedt@goodmis.org> wrote:
>
> On Tue, 30 Jan 2024 01:12:05 -0800
> >
> > I suspect the solution is to make eventfs_create_dir() do the same as
> > the events directory case does, and actually pin the directory dentry
> > and save it off.
>
> I rather not have the create do that because that happens for every event
> directory.

I wasn't thinking straight yesterday - the real fix is to just do a
"d_revalidate()". It's literally why that thing exists: check whether
a dentry is still valid.

In fact, that trivially gets rid of the 'events' subdirectory issues
too, so we can stop doing that horrendous simple_recursive_removal()
too.

Let me reboot into the trivial fix. I just needed to think about this
the right way.

None of this is anything that the VFS layer has any problems with.

               Linus