Date: Mon, 19 Aug 1996 16:43:58 +0200 (MET DST) From: Tor Egge <tegge@idt.ntnu.no> To: FreeBSD-gnats-submit@freebsd.org Subject: kern/1514: mlock fails on readonly regions Message-ID: <199608191443.QAA01466@ikke.idt.unit.no> Resent-Message-ID: <199608191450.HAA21341@freefall.freebsd.org>
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>Number: 1514
>Category: kern
>Synopsis: mlock fails on readonly regions
>Confidential: no
>Severity: non-critical
>Priority: low
>Responsible: freebsd-bugs
>State: open
>Class: sw-bug
>Submitter-Id: current-users
>Arrival-Date: Mon Aug 19 07:50:02 PDT 1996
>Last-Modified:
>Originator: Tor Egge
>Organization:
Norwegian University of Science and Technology, Trondheim, Norway
>Release: FreeBSD 2.2-CURRENT i386
>Environment:
FreeBSD ikke.idt.unit.no 2.2-CURRENT FreeBSD 2.2-CURRENT #5: Mon Aug 19 16:14:50 MET DST 1996 root@ikke.idt.unit.no:/usr/src/sys/compile/TEGGE i386
>Description:
When a memory region is readonly and mlock is called, vm_fault_wire
tries to fault in the region with (VM_PROT_READ|VM_PROT_WRITE) as
flags to vm_fault. This fails, since the memory region is not
writable.
>How-To-Repeat:
mmap a region readonly, and try mlocking it.
Here is the pach I use to enable mlock for normal users (Added one line
from /usr/src/sys/arch/pmax/include/pmap.h in NetBSD-current).
------
*** /usr/snapshot-src/sys/i386/include/pmap.h Tue Jul 30 05:08:57 1996
--- ./pmap.h Mon Aug 19 14:45:28 1996
***************
*** 212,217 ****
--- 212,218 ----
struct pcb;
void pmap_bootstrap __P(( vm_offset_t, vm_offset_t));
+ #define pmap_wired_count(pmap) ((pmap)->pm_stats.wired_count)
pmap_t pmap_kernel __P((void));
void *pmap_mapdev __P((vm_offset_t, vm_size_t));
unsigned * __pure pmap_pte __P((pmap_t, vm_offset_t)) __pure2;
----
>Fix:
Here is a patch that solved the problem for me.
------
diff -c /usr/snapshot-src/sys/vm/vm_fault.c ./vm_fault.c
*** /usr/snapshot-src/sys/vm/vm_fault.c Tue Jul 30 05:08:07 1996
--- ./vm_fault.c Mon Aug 19 16:12:23 1996
***************
*** 840,846 ****
*/
for (va = start; va < end; va += PAGE_SIZE) {
! rv = vm_fault(map, va, VM_PROT_READ|VM_PROT_WRITE, TRUE);
if (rv) {
if (va != start)
vm_fault_unwire(map, start, va);
--- 840,846 ----
*/
for (va = start; va < end; va += PAGE_SIZE) {
! rv = vm_fault(map, va, VM_PROT_READ, TRUE);
if (rv) {
if (va != start)
vm_fault_unwire(map, start, va);
------------
>Audit-Trail:
>Unformatted:
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