Suparna,

Yes your patch did help.  I originally had CONFIG_DEBUG_SLAB=y which
was helping me see problems because the the freed dio was getting
poisoned.  I also tested with CONFIG_DEBUG_PAGEALLOC=y which is
very good at catching these.

I updated your AIO fallback patch plus your AIO race plus I fixed
the bio_count decrement fix.  This patch has all three fixes and
it is working for me.

I fixed the bio_count race, by changing bio_list_lock into bio_lock
and using that for all the bio fields.  I changed bio_count and
bios_in_flight from atomics into int.  They are now proctected by
the bio_lock.  I fixed the race, by in finished_one_bio() by
leaving the bio_count at 1 until after the dio_complete()
and then do the bio_count decrement and wakeup holding the bio_lock.

Take a look, give it a try, and let me know what you think.

I've tested this on my 2-way and so far all my tests have past.
I have more testing to do, but this is working better.

Thanks,

Daniel



On Mon, 2003-11-24 at 01:42, Suparna Bhattacharya wrote:
> On Tue, Nov 18, 2003 at 03:47:53PM -0800, Daniel McNeil wrote:
> > Suparna,
> > 
> > I was unable to reproduce the hang in io_submit() without your patch.
> > I ran aiocp with 1k i/o size constantly for 2 hours and it never hung.
> > 
> > I re-ran with your patch with both as-iosched and deadline and both
> > hung in io_submit().  aiocp would run a few times, but I put the
> > aiocp in a while loop and it hung on the 1st or 2nd time.  It
> > did get most of the way through copying the file before hanging.
> > This is on a 2-proc to ide disks running ext3.
> > 
> 
> Found one race ... not sure if its the one causing the hangs
> you see. The attached patch is not a complete fix (there is one
> other race to close), but it would be interesting to see if 
> this makes any difference for you.
> 
> Regards
> Suparna