D25187.id73656.diff
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	Index: sys/amd64/amd64/pmap.c
	===================================================================
	--- sys/amd64/amd64/pmap.c
	+++ sys/amd64/amd64/pmap.c
	@@ -3807,6 +3807,23 @@
	* one or two pages may be held during the wait, only to be released
	* afterwards. This conservative approach is easily argued to avoid
	* race conditions.
	+ *
	+ * The page index of the page containing PTE at address va is defined
	+ * as follows:
	+ * - for page table (last level),
	+ * ptepindex = pmap_pde_pindex(va) = va >> PDRSHIFT,
	+ * in other words, it is just the index of the PDE.
	+ * - for page directory page,
	+ * ptepindex = NUPDE (number of userland PD entries) +
	+ * (pmap_pde_index(va) >> NPDEPGSHIFT)
	+ * i.e. index of PDPE is put after the last index of PDE,
	+ * - for page directory pointer page,
	+ * ptepindex = NUPDE + NUPDPE + (pmap_pde_index(va) >> (NPDEPGSHIFT +
	+ * NPML4EPGSHIFT),
	+ * i.e. index of pml4e is put after the last index of PDPE.
	+ * In other words, it is sequential number of the corresponding paging entry
	+ * in the order where all entries of the same height are put together, then
	+ * heights are put from deepest to root.
	*/
	static vm_page_t
	_pmap_allocpte(pmap_t pmap, vm_pindex_t ptepindex, struct rwlock **lockp)