On Thu, 17 Apr 2014, Theodore Ts'o wrote:
> On Thu, Apr 17, 2014 at 03:23:13PM -0400, Mikulas Patocka wrote:
> >
> > I hit a bug in ext4 - jbd2 was stuck in an infinite loop when remounting
> > the root filesystem read-only during shutdown.
>
> Is this at all repeatable?
No - it happened just once.
> I suspect what happened is that we're not
> checking the error return from jbd2_log_do_checkpoint(), and if it ran
> into an error doing the jbd2_log_do_checkpoint --- for example, if it
There were no I/O errors on the console when the lockup happened.
> wasn't able to write to the journal --- say, because __wait_cp_io()
> returned -EIO, we might be spinning in the while loop in jbd2_journal_flush:
>
> > while (!err && journal->j_checkpoint_transactions != NULL) {
>
>
> (as you suspected).
>
> I can add some error checking, but it would be interesting to know if
> you can easily reproduce the problem so we can confirm if that's what
> was really going on.
I can write a script that reboots the machine and run it overnight...
> Regards,
>
> - Ted
Mikulas
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