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

From: Andrew Morton
Date: Thu Aug 17 2006 - 02:01:43 EST

On Wed, 16 Aug 2006 20:58:28 -0700
Daniel Phillips <phillips@xxxxxxxxxx> wrote:

> Andrew Morton wrote:
> > Peter Zijlstra <a.p.zijlstra@xxxxxxxxx> 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.
> >
> > That leaves MAP_SHARED, but mm-tracking-shared-dirty-pages.patch will fix
> > that, will it not?
> Hi Andrew,
> What happened to the case where we just fill memory full of dirty file
> pages backed by a remote disk?

Processes which are dirtying those pages throttle at
/proc/sys/vm/dirty_ratio% of memory dirty. So it is not possible to "fill"
memory with dirty pages. If the amount of physical memory which is dirty
exceeds 40%: bug.
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