ext4/004 hangs with -o inlinecrypt,test_dummy_encryption

ext4/004 hangs with -o inlinecrypt,test_dummy_encryption

[Christoph Hellwig]

Hi all,

I've just been wanting to test my changes to the inline encruption
fallback code, and it seems like ext/004 (the only ext4 dump test)
hangs when using the following options:

export MKFS_OPTIONS='-O encrypt'
export MOUNT_OPTIONS="-o inlinecrypt,test_dummy_encryption"

I thought I did not see this before, but it reproduces back to at least
Linux 6.17.  This is in an uptodate Debian trixie VM.  The dump/restore
process look like in weird states:

   4727 ttyS0    T      0:00 /usr/sbin/dump -0 -f - /mnt/scratch/dump_restore_dir
   4728 ttyS0    T      0:00 /usr/sbin/restore -urvf -
   4729 ttyS0    T      0:00 /usr/sbin/dump -0 -f - /mnt/scratch/dump_restore_dir
   4730 ttyS0    T      0:00 /usr/sbin/dump -0 -f - /mnt/scratch/dump_restore_dir
   4731 ttyS0    T      0:00 /usr/sbin/dump -0 -f - /mnt/scratch/dump_restore_dir
   4732 ttyS0    T      0:00 /usr/sbin/dump -0 -f - /mnt/scratch/dump_restore_dir

Re: ext4/004 hangs with -o inlinecrypt,test_dummy_encryption

[Julian Sun]

On 12/8/25 2:59 PM, Christoph Hellwig wrote:
> Hi all,
> 
> I've just been wanting to test my changes to the inline encruption
> fallback code, and it seems like ext/004 (the only ext4 dump test)
> hangs when using the following options:
> 
> export MKFS_OPTIONS='-O encrypt'
> export MOUNT_OPTIONS="-o inlinecrypt,test_dummy_encryption"
> 
> I thought I did not see this before, but it reproduces back to at least
> Linux 6.17.  This is in an uptodate Debian trixie VM.  The dump/restore
> process look like in weird states:
> 
>     4727 ttyS0    T      0:00 /usr/sbin/dump -0 -f - /mnt/scratch/dump_restore_dir
>     4728 ttyS0    T      0:00 /usr/sbin/restore -urvf -
>     4729 ttyS0    T      0:00 /usr/sbin/dump -0 -f - /mnt/scratch/dump_restore_dir
>     4730 ttyS0    T      0:00 /usr/sbin/dump -0 -f - /mnt/scratch/dump_restore_dir
>     4731 ttyS0    T      0:00 /usr/sbin/dump -0 -f - /mnt/scratch/dump_restore_dir
>     4732 ttyS0    T      0:00 /usr/sbin/dump -0 -f - /mnt/scratch/dump_restore_dir
> 

I can reproduce this issue locally with both v6.18 and v6.0. The problem 
disappears after removing test_dummy_encryption, and it still reproduces 
when test_dummy_encryption is set alone in MOUNT_OPTIONS. Therefore, I 
believe the issue lies in test_dummy_encryption — it is an 
implementation of fscrypt.

CC: linux-fscrypt

Thanks,
-- 
Julian Sun <sunjunchao@bytedance.com>

Re: ext4/004 hangs with -o inlinecrypt,test_dummy_encryption

[Julian Sun]

On 12/9/25 4:40 PM, Julian Sun wrote:
> 
> I can reproduce this issue locally with both v6.18 and v6.0. The problem 
> disappears after removing test_dummy_encryption, and it still reproduces 
> when test_dummy_encryption is set alone in MOUNT_OPTIONS. Therefore, I 
> believe the issue lies in test_dummy_encryption — it is an 
> implementation of fscrypt.
> 
> CC: linux-fscrypt
> 
> Thanks,

cc linux-fscrypt

-- 
Julian Sun <sunjunchao@bytedance.com>

Re: ext4/004 hangs with -o inlinecrypt,test_dummy_encryption

[Eric Biggers]

On Tue, Dec 09, 2025 at 05:46:22PM +0800, Julian Sun wrote:
> On 12/9/25 4:40 PM, Julian Sun wrote:
> > 
> > I can reproduce this issue locally with both v6.18 and v6.0. The problem
> > disappears after removing test_dummy_encryption, and it still reproduces
> > when test_dummy_encryption is set alone in MOUNT_OPTIONS. Therefore, I
> > believe the issue lies in test_dummy_encryption — it is an
> > implementation of fscrypt.
> > 
> > CC: linux-fscrypt
> > 
> > Thanks,
> 
> cc linux-fscrypt
> 
> -- 
> Julian Sun <sunjunchao@bytedance.com>
> 

It seems to be a known failure.  ext4/004, along with various other
tests, is excluded by
https://github.com/tytso/xfstests-bld/blob/master/test-appliance/files/root/fs/ext4/cfg/encrypt.exclude
as follows:

    ext4/004	// dump/restore doesn't handle quotas

I'm not sure why the comment mentions quotas.  It probably should say
"encryption", not "quotas".

Either way, the exclusion logic in xfstests-bld really should be
incorporated directly into xfstests, e.g. by using
_exclude_test_mount_option "test_dummy_encryption".

This seems to be a wider issue.  Effectively, ext4's exclusion lists for
xfstests are being maintained outside of xfstests itself.

- Eric