Messages in this thread |  | | Date | Wed, 28 Nov 2012 15:53:45 +0200 | From | Gleb Natapov <> | Subject | Re: [RFC PATCH v2] Add rcu user eqs exception hooks for async page fault |
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On Wed, Nov 28, 2012 at 01:55:42PM +0100, Frederic Weisbecker wrote: > > So I still want to remove it. And later if it shows that we really needs > > rcu somewhere in this code path, maybe we could use RCU_NONIDLE() to > > protect it. ( The suspicious RCU usage reported in commit > > c5e015d4949aa665 seems related to schedule(), which is not in the code > > path if we are in cpu idle eqs ) > > Yes but if rcu_irq_*() calls are fine to be called there, and I > believe they are because exception_enter() exits the user mode, we > should start to protect there right now instead of waiting for a > potential future warning of illegal RCU use. > Async page not present is not much different from regular page fault exception when it happens not on idle task (regular #PF cannot happen on idle task), but code have a special handling for idle task. So why do you think rcu_irq_*() is required here, but not in page fault handler?
> > > > I think we still need Gleb's patch about the idle check in > > kvm_async_pf_task_wait(), and maybe another patch for the > > exit_idle()/enter_idle() issue. > > Right. > Done.
-- Gleb.
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