Re: [RFC] RT-patch update to remove the global pi_lock

[Ingo Molnar <mingo@elte.hu>]

* Steven Rostedt <rostedt@goodmis.org> wrote:

> > does the system truly lock up, or is this some transitional condition?  
> > In any case, i agree that this should be debugged independently of the 
> > pi_lock patch.
> 
> Hmm, I forgot that you took out the bit_spin_lock fixes.  I think this 
> may be caused by them.  I haven't look further into it yet.

yeah, i took them out because they clashed with upstream changes. Note 
that i meanwhile also introduced a per-bh lock, which might make it 
easier to fix the deadlock:

 --- linux.orig/fs/buffer.c
 +++ linux/fs/buffer.c
 @@ -537,8 +537,7 @@ static void end_buffer_async_read(struct
          * decide that the page is now completely done.
          */
         first = page_buffers(page);
 -       local_irq_save(flags);
 -       bit_spin_lock(BH_Uptodate_Lock, &first->b_state);
 +       spin_lock_irqsave(&first->b_uptodate_lock, flags);
         clear_buffer_async_read(bh);
         unlock_buffer(bh);
         tmp = bh;

could jbd reuse this lock - or would it need another lock?

	Ingo