Index: head/lib/libc/sys/mincore.2
===================================================================
--- head/lib/libc/sys/mincore.2
+++ head/lib/libc/sys/mincore.2
@@ -28,7 +28,7 @@
 .\"	@(#)mincore.2	8.1 (Berkeley) 6/9/93
 .\" $FreeBSD$
 .\"
-.Dd June 1, 2018
+.Dd January 7, 2019
 .Dt MINCORE 2
 .Os
 .Sh NAME
@@ -47,7 +47,8 @@
 .Fa addr
 and continuing for
 .Fa len
-bytes is resident.
+bytes is resident or mapped, depending on the value of sysctl
+.Va vm.mincore_mapped .
 .\"The beginning address,
 .\".Fa addr ,
 .\"is first rounded down to a multiple of the page size (see
@@ -85,6 +86,18 @@
 with the
 .Xr mlock 2
 system call.
+.Pp
+If the
+.Va vm.mincore_mapped
+sysctl is set to a non-zero value (default), only the current process'
+mappings of the pages in the specified virtual address range are examined.
+This does not preclude the system from returning
+.Dv MINCORE_REFERENCED_OTHER
+and
+.Dv MINCORE_MODIFIED_OTHER
+statuses.
+Otherwise, if the sysctl value is zero, all resident pages backing the
+specified address range are examined, regardless of the mapping state.
 .Sh RETURN VALUES
 .Rv -std mincore
 .Sh ERRORS
Index: head/sys/vm/vm_mmap.c
===================================================================
--- head/sys/vm/vm_mmap.c
+++ head/sys/vm/vm_mmap.c
@@ -97,6 +97,9 @@
 int old_mlock = 0;
 SYSCTL_INT(_vm, OID_AUTO, old_mlock, CTLFLAG_RWTUN, &old_mlock, 0,
     "Do not apply RLIMIT_MEMLOCK on mlockall");
+static int mincore_mapped = 1;
+SYSCTL_INT(_vm, OID_AUTO, mincore_mapped, CTLFLAG_RWTUN, &mincore_mapped, 0,
+    "mincore reports mappings, not residency");
 
 #ifdef MAP_32BIT
 #define	MAP_32BIT_MAX_ADDR	((vm_offset_t)1 << 31)
@@ -808,7 +811,16 @@
 		retry:
 			m = NULL;
 			mincoreinfo = pmap_mincore(pmap, addr, &locked_pa);
-			if (locked_pa != 0) {
+			if (mincore_mapped) {
+				/*
+				 * We only care about this pmap's
+				 * mapping of the page, if any.
+				 */
+				if (locked_pa != 0) {
+					vm_page_unlock(PHYS_TO_VM_PAGE(
+					    locked_pa));
+				}
+			} else if (locked_pa != 0) {
 				/*
 				 * The page is mapped by this process but not
 				 * both accessed and modified.  It is also