Re: RFC: Bouncebuffer fixes

[Andrea Arcangeli <andrea@suse.de>]

On Sun, Apr 29, 2001 at 03:56:26AM -0400, Arjan van de Ven wrote:
> This looks like the code in Alan's tree around 2.4.3-ac7, and that is NOT 
> enough to fix the deadlock. With that patch, tests deadlock within 10 minutes....
> 
> One of the reasons it deadlocks is because GFP_BUFFER can sleep here,
> without the guarantee of progress. The regular VM threads that should

GFP_BUFFER doesn't provide guarantee of progress and that's fine, as far
as GFP_BUFFER allocations returns NULL eventually there should be no
problem. The fact some emergency buffer is in flight is just the guarantee
of progress because after unplugging tq_disk we know those emergency
buffers will be released without the need of further memory allocations.

If GFP_BUFFER allocation never returns and they deadlocks inside the VM
that's a completly unrelated bug and I think you shouldn't workaround it
in highmem.c.

Andrea
--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org.  For more info on Linux MM,
see: http://www.linux.eu.org/Linux-MM/