[src/trunk]: src/sys/rump/librump/rumpkern make sure we don't underflow the m...

[pooka <pooka%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/b0471798a445
branches:  trunk
changeset: 329903:b0471798a445
user:      pooka <pooka%NetBSD.org@localhost>
date:      Fri Jun 13 11:53:48 2014 +0000

description:
make sure we don't underflow the memlimit

diffstat:

 sys/rump/librump/rumpkern/vm.c |  14 +++++++++-----
 1 files changed, 9 insertions(+), 5 deletions(-)

diffs (50 lines):

diff -r dddab24a3f3f -r b0471798a445 sys/rump/librump/rumpkern/vm.c
--- a/sys/rump/librump/rumpkern/vm.c    Fri Jun 13 11:48:56 2014 +0000
+++ b/sys/rump/librump/rumpkern/vm.c    Fri Jun 13 11:53:48 2014 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: vm.c,v 1.157 2014/06/13 11:48:56 pooka Exp $   */
+/*     $NetBSD: vm.c,v 1.158 2014/06/13 11:53:48 pooka Exp $   */
 
 /*
  * Copyright (c) 2007-2011 Antti Kantee.  All Rights Reserved.
@@ -41,7 +41,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: vm.c,v 1.157 2014/06/13 11:48:56 pooka Exp $");
+__KERNEL_RCSID(0, "$NetBSD: vm.c,v 1.158 2014/06/13 11:53:48 pooka Exp $");
 
 #include <sys/param.h>
 #include <sys/atomic.h>
@@ -100,6 +100,7 @@
 static unsigned long dddlim;           /* 90% of memory limit used */
 #define NEED_PAGEDAEMON() \
     (rump_physmemlimit != RUMPMEM_UNLIMITED && curphysmem > dddlim)
+#define PDRESERVE (2*MAXPHYS)
 
 /*
  * Try to free two pages worth of pages from objects.
@@ -308,8 +309,12 @@
                        panic("uvm_init: RUMP_MEMLIMIT overflow: %s", buf);
 
                /* reserve some memory for the pager */
+               if (rump_physmemlimit <= PDRESERVE)
+                       panic("uvm_init: system reserves %d bytes of mem, "
+                           "only %lu bytes given",
+                           PDRESERVE, rump_physmemlimit);
                pdlimit = rump_physmemlimit;
-               rump_physmemlimit -= 2*MAXPHYS;
+               rump_physmemlimit -= PDRESERVE;
 
                if (pdlimit < 1024*1024)
                        printf("uvm_init: WARNING: <1MB RAM limit, "
@@ -331,8 +336,7 @@
                uvmexp.npages = physmem;
        } else {
                uvmexp.npages = pdlimit >> PAGE_SHIFT;
-               uvmexp.reserve_pagedaemon
-                   = (pdlimit-rump_physmemlimit) >> PAGE_SHIFT;
+               uvmexp.reserve_pagedaemon = PDRESERVE >> PAGE_SHIFT;
                uvmexp.freetarg = (rump_physmemlimit-dddlim) >> PAGE_SHIFT;
        }
        /*