Hi Andres,
On Mon, Sep 22, 2014 at 02:54:42PM -0700, Andres Lagar-Cavilla wrote:

1. We were calling clear_flush_young_notify in unmap_one, but we are
within an mmu notifier invalidate range scope. The spte exists no more
(due to range_start) and the accessed bit info has already been
propagated (due to kvm_pfn_set_accessed). Simply call
clear_flush_young.

2. We clear_flush_young on a primary MMU PMD, but this may be mapped
as a collection of PTEs by the secondary MMU (e.g. during log-dirty).
This required expanding the interface of the clear_flush_young mmu
notifier, so a lot of code has been trivially touched.

3. In the absence of shadow_accessed_mask (e.g. EPT A bit), we emulate
the access bit by blowing the spte. This requires proper synchronizing
with MMU notifier consumers, like every other removal of spte's does.

[...]

---
+	BUG_ON(!shadow_accessed_mask);

	for (sptep = rmap_get_first(*rmapp, &iter); sptep;
	     sptep = rmap_get_next(&iter)) {
+		struct kvm_mmu_page *sp;
+		gfn_t gfn;
		BUG_ON(!is_shadow_present_pte(*sptep));
+		/* From spte to gfn. */
+		sp = page_header(__pa(sptep));
+		gfn = kvm_mmu_page_get_gfn(sp, sptep - sp->spt);

		if (*sptep & shadow_accessed_mask) {
			young = 1;
			clear_bit((ffs(shadow_accessed_mask) - 1),
				 (unsigned long *)sptep);
		}
+		trace_kvm_age_page(gfn, slot, young);

IIUC, all the rmapps in this for loop are against the same gfn which
results in the above trace point dump the message duplicated.

Regards,
Wanpeng Li 

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