Dear frederic,
> Hi Bastien,
> 
> This really looks like a hung task detector report.
> Several tasks are stuck in queue_log_writer(), waiting
> to be woken up on the "journal->j_join_wait" event and
> that never happens because the waker is also stuck.
> The problem is your report doesn't show where the waker
> is stuck, but the hung task detector reports it, it just
> did before or after the chunk you've posted.
> 
> If you could provide me the entire report, I could fix this
> easily.

I have manged to reproduce it after six hour of stress. Unfornatly locked was 
disabled due to a known non bug, in the init sequence. I have used sysrq -t in 
order to get more information to you.

Do I need to try to reproduce it, with a newer kernel ? Or it is sufficient ?