Author: kib
Date: Mon Jan 14 07:24:49 2019
New Revision: 343015
URL: https://svnweb.freebsd.org/changeset/base/343015
Log:
MFC r342853:
Add a tunable which changes mincore(2) algorithm to only report data
from the local mapping.
Modified:
stable/12/lib/libc/sys/mincore.2
stable/12/sys/vm/vm_mmap.c
Directory Properties:
stable/12/ (props changed)
Modified: stable/12/lib/libc/sys/mincore.2
==============================================================================
--- stable/12/lib/libc/sys/mincore.2 Mon Jan 14 07:22:58 2019
(r343014)
+++ stable/12/lib/libc/sys/mincore.2 Mon Jan 14 07:24:49 2019
(r343015)
@@ -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 @@ system call determines whether each of the pages in th
.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 @@ The only way to ensure that a page is resident is to l
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
Modified: stable/12/sys/vm/vm_mmap.c
==============================================================================
--- stable/12/sys/vm/vm_mmap.c Mon Jan 14 07:22:58 2019 (r343014)
+++ stable/12/sys/vm/vm_mmap.c Mon Jan 14 07:24:49 2019 (r343015)
@@ -97,6 +97,9 @@ __FBSDID("$FreeBSD$");
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)
@@ -814,7 +817,16 @@ RestartScan:
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
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