On Mon, 14 Aug 2006 07:03:55 +0200
Peter Zijlstra [off-list ref] wrote:

On Sun, 2006-08-13 at 21:58 -0700, Andrew Morton wrote:

quoted

On Mon, 14 Aug 2006 06:40:53 +0200
Peter Zijlstra [off-list ref] wrote:

quoted

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.

We could track dirty anonymous memory and throttle.

Also, there must be some value of /proc/sys/vm/min_free_kbytes at which a
machine is no longer deadlockable with any of these tricks.  Do we know
what level that is?

quoted

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.

But there's lots of reclaimable pagecache around and kswapd will free it
up?