Subject: Re: [RFC][PATCH 2/9] deadlock prevention core

From: Peter Zijlstra <[email-masked]>
Date: Mon, 14 Aug 2006 07:03:55 +0200

On Sun, 2006-08-13 at 21:58 -0700, Andrew Morton wrote:
> On Mon, 14 Aug 2006 06:40:53 +0200
> Peter Zijlstra <[email-masked]> wrote:
> 
> > Testcase:
> > 
> > Mount an NBD device as sole swap device and mmap > physical RAM, then
> > loop through touching pages only once.
> 
> Fix: don't try to swap over the network.  Yes, there may be some scenarios
> where people have no local storage, but it's reasonable to expect anyone
> who is using Linux as an "enterprise storage platform" to stick a local
> disk on the thing for swap.

I wish you were right, however there seems to be a large demand to go
diskless and swap over iSCSI because disks seem to be the nr. 1 failing
piece of hardware in systems these days.

> That leaves MAP_SHARED, but mm-tracking-shared-dirty-pages.patch will fix
> that, will it not?

Will makes it less likely. One can still have memory pressure, the
remaining bits of memory can still get stuck in socket queues for
blocked processes.