Messages in this thread | | | Date | Thu, 01 Apr 2010 18:39:48 +0300 | From | Avi Kivity <> | Subject | Re: [COUNTERPATCH] mm: avoid overflowing preempt_count() in mmu_take_all_locks() |
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On 04/01/2010 06:36 PM, Andrea Arcangeli wrote: > On Thu, Apr 01, 2010 at 01:16:32PM +0200, Peter Zijlstra wrote: > >> On Thu, 2010-04-01 at 14:13 +0300, Avi Kivity wrote: >> >> >>> If someone is willing to audit all code paths to make sure these locks >>> are always taken in schedulable context I agree that's a better fix. >>> >> They had better be, they're not irq-safe. Also that's what lockdep is >> for. >> > In my original patchset I included patches from Christoph to convert > those locks to mutexes, there was apparently no problem at all with > that. But frankly I think the only problem here is the warning. The > only compliant we ever had here is from developers, no users at > all. If this was a practical problem I think we should have heard > something by now with so many KVM users out there (and gru too). > > The only single reason I'd go for mutexes would be to accommodate > XPMEM requirements once and for all, no other reason. >
There is also a minor benefit for kvm. Reduced latency over large mmu operations; code simplification (we now have some copy_from_user_inatomic() that could be simplified).
-- error compiling committee.c: too many arguments to function
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