Re: alloc_area_pte: page already exists

[Andrea Arcangeli <andrea@suse.de>]

On Thu, Aug 09, 2001 at 05:12:43PM +0200, Bjorn Wesen wrote:
> Yes, I found it. The irq which signals end-of-I/O also frees the kiovec,
> which is bad. But it seemed that what would happen then would be deadlocks
> (due to the spinlocks) and not races - but I'll try to make it free in a

In SMP the most obvious sympthom would be a deadlock right, but maybe
you're testing with a kernel compiled UP?

The locking there looks quite sane.

> task or something instead (there is no kernel context for the "calling"
> process because the driver is asynchronous so the context which did the
> alloc_kiovec etc. has exited when the irq comes later) and see if it works
> better.

Ok.

> > BTW, you should also avoid all the kiobuf allocation in all the fast
> > paths, try to pre-allocate it in a slow path to deliver higher
> > performance. (shortly we'll split the bh/blocks array out of the kiobuf
> 
> Ok, that's probably not a problem since the allocation is done in a normal
> system-call context.

Ok.

Andrea