Messages in this thread | | | Date | Wed, 14 Mar 2012 07:58:13 -0300 | From | Marcelo Tosatti <> | Subject | Re: [PATCH 2/4] KVM: Avoid checking huge page mappings in get_dirty_log() |
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On Wed, Mar 14, 2012 at 02:34:32PM +0900, Takuya Yoshikawa wrote: > Marcelo Tosatti <mtosatti@redhat.com> wrote: > > > guest fault enable dirty logging > > > > tdp_page_fault (all _page_fault functions) kvm_set_memory_region > > > > > > level = mapping_level(vcpu, gfn) > > (finds level == 2 or 3) > > > > > > rcu_assign_pointer(slot > > with > > ->dirty_bitmap) > > synchronize_srcu_expedited() > > Isn't here still in the SRCU read-side critical section? > > > schedule() > > kvm_arch_commit_memory_region() > > spin_lock(mmu_lock) > > kvm_mmu_slot_remove_write_access() > > removes large sptes > > spin_unlock(mmu_lock) > > spin_lock(mmu_lock) > > create large spte accordingly > > to level above > > spin_unlock(mmu_lock) > > > > If so, we cannot start kvm_arch_commit_memory_region() until the completion > of the SRCU critical section and this race will not happen. > > Takuya
Correct.
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