Revert "vm_phys_enqueue_contig: handle npages==0"

This reverts commit 1a7fcf6d51.

Peter Holm reported a problem, so I'm reverting now and looking for
the problem later.

sys/vm/vm_phys.c

@@ -72,8 +72,6 @@ __FBSDID("$FreeBSD$");
 
 _Static_assert(sizeof(long) * NBBY >= VM_PHYSSEG_MAX,
     "Too many physsegs.");
-_Static_assert(sizeof(long long) >= sizeof(vm_paddr_t),
-    "vm_paddr_t too big for ffsll, flsll.");
 
 #ifdef NUMA
 struct mem_affinity __read_mostly *mem_affinity;
@@ -692,16 +690,18 @@ vm_phys_split_pages(vm_page_t m, int oind, struct vm_freelist *fl, int order,
  *
  * The physical page m's buddy must not be free.
  */
-static vm_page_t
+static void
 vm_phys_enq_range(vm_page_t m, u_int npages, struct vm_freelist *fl, int tail)
 {
+	u_int n;
 	int order;
 
+	KASSERT(npages > 0, ("vm_phys_enq_range: npages is 0"));
 	KASSERT(((VM_PAGE_TO_PHYS(m) + npages * PAGE_SIZE) &
 	    ((PAGE_SIZE << (fls(npages) - 1)) - 1)) == 0,
 	    ("vm_phys_enq_range: page %p and npages %u are misaligned",
 	    m, npages));
-	while (npages > 0) {
+	do {
 		KASSERT(m->order == VM_NFREEORDER,
 		    ("vm_phys_enq_range: page %p has unexpected order %d",
 		    m, m->order));
@@ -709,10 +709,10 @@ vm_phys_enq_range(vm_page_t m, u_int npages, struct vm_freelist *fl, int tail)
 		KASSERT(order < VM_NFREEORDER,
 		    ("vm_phys_enq_range: order %d is out of range", order));
 		vm_freelist_add(fl, m, order, tail);
-		m += 1 << order;
+		n = 1 << order;
-		npages -= 1 << order;
+		m += n;
-	}
+		npages -= n;
-	return (m);
+	} while (npages > 0);
 }
 
 /*
@@ -744,7 +744,7 @@ vm_phys_alloc_npages(int domain, int pool, int npages, vm_page_t ma[])
 {
 	struct vm_freelist *alt, *fl;
 	vm_page_t m;
-	int avail, end, flind, freelist, i, oind, pind;
+	int avail, end, flind, freelist, i, need, oind, pind;
 
 	KASSERT(domain >= 0 && domain < vm_ndomains,
 	    ("vm_phys_alloc_npages: domain %d is out of range", domain));
@@ -762,18 +762,20 @@ vm_phys_alloc_npages(int domain, int pool, int npages, vm_page_t ma[])
 		for (oind = 0; oind < VM_NFREEORDER; oind++) {
 			while ((m = TAILQ_FIRST(&fl[oind].pl)) != NULL) {
 				vm_freelist_rem(fl, m, oind);
-				avail = i + (1 << oind);
+				avail = 1 << oind;
-				end = imin(npages, avail);
+				need = imin(npages - i, avail);
-				while (i < end)
+				for (end = i + need; i < end;)
 					ma[i++] = m++;
-				if (i == npages) {
+				if (need < avail) {
 					/*
-					 * Return excess pages to fl.  Its order
+					 * Return excess pages to fl.  Its
-					 * [0, oind) queues are empty.
+					 * order [0, oind) queues are empty.
 					 */
-					vm_phys_enq_range(m, avail - i, fl, 1);
+					vm_phys_enq_range(m, avail - need, fl,
+					    1);
+					return (npages);
+				} else if (i == npages)
 					return (npages);
-				}
 			}
 		}
 		for (oind = VM_NFREEORDER - 1; oind >= 0; oind--) {
@@ -783,20 +785,21 @@ vm_phys_alloc_npages(int domain, int pool, int npages, vm_page_t ma[])
 				    NULL) {
 					vm_freelist_rem(alt, m, oind);
 					vm_phys_set_pool(pool, m, oind);
-					avail = i + (1 << oind);
+					avail = 1 << oind;
-					end = imin(npages, avail);
+					need = imin(npages - i, avail);
-					while (i < end)
+					for (end = i + need; i < end;)
 						ma[i++] = m++;
-					if (i == npages) {
+					if (need < avail) {
 						/*
 						 * Return excess pages to fl.
 						 * Its order [0, oind) queues
 						 * are empty.
 						 */
-						vm_phys_enq_range(m, avail - i,
+						vm_phys_enq_range(m, avail -
-						    fl, 1);
+						    need, fl, 1);
+						return (npages);
+					} else if (i == npages)
 						return (npages);
-					}
 				}
 			}
 		}
@@ -1143,7 +1146,7 @@ max_order(vm_page_t m)
 	 * because the size of a physical address exceeds the size of
 	 * a long.
 	 */
-	return (min(ffsll(VM_PAGE_TO_PHYS(m) >> PAGE_SHIFT) - 1,
+	return (min(ffsl(VM_PAGE_TO_PHYS(m) >> PAGE_SHIFT) - 1,
 	    VM_NFREEORDER - 1));
 }
 
@@ -1159,7 +1162,6 @@ vm_phys_enqueue_contig(vm_page_t m, u_long npages)
 	struct vm_freelist *fl;
 	struct vm_phys_seg *seg;
 	vm_page_t m_end;
-	vm_paddr_t diff, lo;
 	int order;
 
 	/*
@@ -1171,15 +1173,15 @@ vm_phys_enqueue_contig(vm_page_t m, u_long npages)
 	fl = (*seg->free_queues)[m->pool];
 	m_end = m + npages;
 	/* Free blocks of increasing size. */
-	lo = VM_PAGE_TO_PHYS(m) >> PAGE_SHIFT;
+	while ((order = max_order(m)) < VM_NFREEORDER - 1 &&
-	if (m < m_end &&
+	    m + (1 << order) <= m_end) {
-	    (diff = lo ^ (lo + npages - 1)) != 0) {
+		KASSERT(seg == &vm_phys_segs[m->segind],
-		order = min(flsll(diff) - 1, VM_NFREEORDER - 1);
+		    ("%s: page range [%p,%p) spans multiple segments",
-		m = vm_phys_enq_range(m, roundup2(-lo, 1 << order), fl, 1);
+		    __func__, m_end - npages, m));
+		vm_freelist_add(fl, m, order, 1);
+		m += 1 << order;
 	}
-
 	/* Free blocks of maximum size. */
-	order = VM_NFREEORDER - 1;
 	while (m + (1 << order) <= m_end) {
 		KASSERT(seg == &vm_phys_segs[m->segind],
 		    ("%s: page range [%p,%p) spans multiple segments",
@@ -1558,8 +1560,10 @@ vm_phys_alloc_contig(int domain, u_long npages, vm_paddr_t low, vm_paddr_t high,
 			vm_phys_set_pool(VM_FREEPOOL_DEFAULT, m, oind);
 	}
 	/* Return excess pages to the free lists. */
+	if (&m_run[npages] < m) {
 		fl = (*queues)[VM_FREEPOOL_DEFAULT];
 		vm_phys_enq_range(&m_run[npages], m - &m_run[npages], fl, 0);
+	}
 	return (m_run);
 }