Messages in this thread | | | Date | Thu, 1 Apr 2010 09:14:18 -0700 | From | "Paul E. McKenney" <> | Subject | Re: [COUNTERPATCH] mm: avoid overflowing preempt_count() in mmu_take_all_locks() |
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On Thu, Apr 01, 2010 at 05:56:46PM +0200, Peter Zijlstra wrote: > On Thu, 2010-04-01 at 18:51 +0300, Avi Kivity wrote: > > On 04/01/2010 06:42 PM, Andrea Arcangeli wrote: > > > On Thu, Apr 01, 2010 at 01:43:14PM +0200, Peter Zijlstra wrote: > > > > > >> On Thu, 2010-04-01 at 13:27 +0200, Peter Zijlstra wrote: > > >> > > >>> I've almost got a patch done that converts those two, still need to look > > >>> where that tasklist_lock muck happens. > > >>> > > >> OK, so the below builds and boots, only need to track down that > > >> tasklist_lock nesting, but I got to run an errand first. > > >> > > > You should have a look at my old patchset where Christoph already > > > implemented this (and not for decreasing latency but to allow > > > scheduling in mmu notifier handlers, only needed by XPMEM): > > > > > > http://www.kernel.org/pub/linux/kernel/people/andrea/patches/v2.6/2.6.26-rc7/mmu-notifier-v18/ > > > > > > The ugliest part of it (that I think you missed below) is the breakage > > > of the RCU locking in the anon-vma which requires adding refcounting > > > to it. That was the worst part of the conversion as far as I can tell. > > > > > > http://www.kernel.org/pub/linux/kernel/people/andrea/patches/v2.6/2.6.26-rc7/mmu-notifier-v18/anon-vma > > > > > > > Can we use srcu now instead? > > I would much rather we make call_rcu_preempt() available at all times.
Even in !CONFIG_PREEMPT kernels? Or am I missing your point?
Thanx, Paul
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