Perform more checking for proper loading of the UPAGES when a process

is swapped in.  Also, remove unnecessary map locking/unlocking during
selection of processes to be swapped out.

This code might afford proper panics as opposed to spontaneous reboots
on certain systems.  This should allow us to debug these problems better.

1 files changed, 19 insertions, 13 deletions

diff --git a/sys/vm/vm_glue.c b/sys/vm/vm_glue.c
index 4a2acba..30b5bd8 100644
--- a/sys/vm/vm_glue.c
+++ b/sys/vm/vm_glue.c
@@ -59,7 +59,7 @@
  * any improvements or extensions that they make and grant Carnegie the
  * rights to redistribute these changes.
  *
- * $Id: vm_glue.c,v 1.25 1995/09/09 18:10:35 davidg Exp $
+ * $Id: vm_glue.c,v 1.26 1995/09/17 01:46:03 davidg Exp $
  */
 
 #include <sys/param.h>
@@ -323,25 +323,33 @@ faultin(p)
 
 	if ((p->p_flag & P_INMEM) == 0) {
 		vm_map_t map;
+		int error;
 
 		++p->p_lock;
 
 		map = &p->p_vmspace->vm_map;
 		/* force the page table encompassing the kernel stack (upages) */
 		ptaddr = trunc_page((u_int) vtopte(kstack));
-		vm_map_pageable(map, ptaddr, ptaddr + NBPG, FALSE);
+		error = vm_map_pageable(map, ptaddr, ptaddr + NBPG, FALSE);
+		if (error)
+			panic("faultin: wire of PT failed. error=%d", error);
 
 		/* wire in the UPAGES */
-		vm_map_pageable(map, (vm_offset_t) kstack,
+		error = vm_map_pageable(map, (vm_offset_t) kstack,
 		    (vm_offset_t) kstack + UPAGES * NBPG, FALSE);
+		if (error)
+			panic("faultin: wire of UPAGES failed. error=%d", error);
 
 		/* and map them nicely into the kernel pmap */
 		for (i = 0; i < UPAGES; i++) {
 			vm_offset_t off = i * NBPG;
 			vm_offset_t pa = (vm_offset_t)
-			pmap_extract(&p->p_vmspace->vm_pmap,
-			    (vm_offset_t) kstack + off);
+				pmap_extract(&p->p_vmspace->vm_pmap,
+				    (vm_offset_t) kstack + off);
 
+			if (pa == 0) 
+				panic("faultin: missing page for UPAGES\n");
+				
 			pmap_enter(vm_map_pmap(u_map),
 			    ((vm_offset_t) p->p_addr) + off,
 			    pa, VM_PROT_READ | VM_PROT_WRITE, 1);
@@ -461,7 +469,8 @@ retry:
 			 * do not swapout a process waiting on a critical
 			 * event of some kind
 			 */
-			if ((p->p_priority & 0x7f) < PSOCK)
+			if (((p->p_priority & 0x7f) < PSOCK) ||
+				(p->p_slptime <= 4))
 				continue;
 
 			vm_map_reference(&p->p_vmspace->vm_map);
@@ -478,13 +487,10 @@ retry:
 			 * If the process has been asleep for awhile and had
 			 * most of its pages taken away already, swap it out.
 			 */
-			if (p->p_slptime > 4) {
-				swapout(p);
-				vm_map_deallocate(&p->p_vmspace->vm_map);
-				didswap++;
-				goto retry;
-			}
+			swapout(p);
 			vm_map_deallocate(&p->p_vmspace->vm_map);
+			didswap++;
+			goto retry;
 		}
 	}
 	/*
@@ -511,11 +517,11 @@ swapout(p)
 
 	(void) splhigh();
 	p->p_flag &= ~P_INMEM;
+	p->p_flag |= P_SWAPPING;
 	if (p->p_stat == SRUN)
 		remrq(p);
 	(void) spl0();
 
-	p->p_flag |= P_SWAPPING;
 	/*
 	 * let the upages be paged
 	 */