linux-ext4 - Re: [Bug report]: fstests g/388 crash on ext4, BUG: kernel NULL pointer dereference, address: 0000000000000000

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Message-ID: <20240715142403.GA70013@mit.edu>
Date: Mon, 15 Jul 2024 10:24:03 -0400
From: "Theodore Ts'o" <tytso@....edu>
To: Daniel Gomez <da.gomez@...sung.com>
Cc: Zorro Lang <zlang@...hat.com>,
        "linux-ext4@...r.kernel.org" <linux-ext4@...r.kernel.org>,
        "fstests@...r.kernel.org" <fstests@...r.kernel.org>,
        "Darrick J. Wong" <djwong@...nel.org>
Subject: Re: [Bug report]: fstests g/388 crash on ext4, BUG: kernel NULL
 pointer dereference, address: 0000000000000000

On Mon, Jul 15, 2024 at 08:01:54AM +0000, Daniel Gomez wrote:
> 
> My guess is that '-o acl,user_xattr' [1] options are now included in
> the scratch device and they were not before. This is what patch 4
> fixes. f2fs, tmpfs, reiserfs, gfs2 and ext* will be affected as well
> with their respective default mount options.

At least for ext4, acl and user_xattr are enabled by default:

% kvm-xfstests shell
...
root@...-xfstests:~# mount -t ext4 /dev/vdc /vdc
[   11.207917] EXT4-fs (vdc): recovery complete
[   11.209103] EXT4-fs (vdc): mounted filesystem 881ec32f-72a0-4b10-9a3f-a68c68f31f40 r/w with ordered data mode. Quota mode: none.
root@...-xfstests:~# cat /proc/fs/ext4/vdc/options 
...
user_xattr
acl
...
root@...-xfstests:~# 

> [1] From _common_mount_opts(). Snippet:
> 
> 	ext2|ext3|ext4|ext4dev)
> 		# acls & xattrs aren't turned on by default on ext$FOO
> 		echo "-o acl,user_xattr $EXT_MOUNT_OPTIONS"
> 		;;

Yeah, that hasn't been true for a while....

commit ea6633369458992241599c9d9ebadffaeddec164
Author: Eric Sandeen <sandeen@...hat.com>
Date:   Wed Feb 23 17:51:51 2011 -0500

    ext4: enable acls and user_xattr by default
    
    There's no good reason to require the extra step of providing
    a mount option for acl or user_xattr once the feature is configured
    on; no other filesystem that I know of requires this.

So we probably remove that bit from _common_mount_opts.  :-)

    	       	      	       	    			 - Ted