Make vm_contig_grow_cache() extern, and use it when vm_phys_alloc_contig()

fails to allocate MIPS page table pages.  The current usage of VM_WAIT in
case of vm_phys_alloc_contig() failure is not correct, because:

"There is no guarantee that any of the available free (or cached) pages
after the VM_WAIT will fall within the range of suitable physical
addresses.  Every time this function sleeps and a single page is freed
(or cached) by someone else, this function will be reawakened.  With
a little bad luck, you could spin indefinitely."

We also add low and high parameters to vm_contig_grow_cache() and
vm_contig_launder() so that we restrict vm_contig_launder() to the range
of pages we are interested in.

Reported by: alc

Reviewed by:	alc
Approved by:	rrs (mentor)

2 files changed, 13 insertions, 9 deletions

diff --git a/sys/vm/vm_contig.c b/sys/vm/vm_contig.c
index 025031e..b9e0579 100644
--- a/sys/vm/vm_contig.c
+++ b/sys/vm/vm_contig.c
@@ -87,8 +87,6 @@ __FBSDID("$FreeBSD$");
 #include <vm/vm_phys.h>
 #include <vm/vm_extern.h>
 
-static void vm_contig_grow_cache(int tries);
-
 static int
 vm_contig_launder_page(vm_page_t m, vm_page_t *next)
 {
@@ -157,9 +155,10 @@ vm_contig_launder_page(vm_page_t m, vm_page_t *next)
 }
 
 static int
-vm_contig_launder(int queue)
+vm_contig_launder(int queue, vm_paddr_t low, vm_paddr_t high)
 {
 	vm_page_t m, next;
+	vm_paddr_t pa;
 	int error;
 
 	TAILQ_FOREACH_SAFE(m, &vm_page_queues[queue].pl, pageq, next) {
@@ -168,6 +167,10 @@ vm_contig_launder(int queue)
 		if ((m->flags & PG_MARKER) != 0)
 			continue;
 
+		pa = VM_PAGE_TO_PHYS(m);
+		if (pa < low || pa + PAGE_SIZE > high)
+			continue;
+
 		if (!vm_pageout_page_lock(m, &next)) {
 			vm_page_unlock(m);
 			continue;
@@ -203,8 +206,8 @@ vm_page_release_contig(vm_page_t m, vm_pindex_t count)
 /*
  * Increase the number of cached pages.
  */
-static void
-vm_contig_grow_cache(int tries)
+void
+vm_contig_grow_cache(int tries, vm_paddr_t low, vm_paddr_t high)
 {
 	int actl, actmax, inactl, inactmax;
 
@@ -214,11 +217,11 @@ vm_contig_grow_cache(int tries)
 	actl = 0;
 	actmax = tries < 2 ? 0 : cnt.v_active_count;
 again:
-	if (inactl < inactmax && vm_contig_launder(PQ_INACTIVE)) {
+	if (inactl < inactmax && vm_contig_launder(PQ_INACTIVE, low, high)) {
 		inactl++;
 		goto again;
 	}
-	if (actl < actmax && vm_contig_launder(PQ_ACTIVE)) {
+	if (actl < actmax && vm_contig_launder(PQ_ACTIVE, low, high)) {
 		actl++;
 		goto again;
 	}
@@ -261,7 +264,7 @@ retry:
 			if (tries < ((flags & M_NOWAIT) != 0 ? 1 : 3)) {
 				VM_OBJECT_UNLOCK(object);
 				vm_map_unlock(map);
-				vm_contig_grow_cache(tries);
+				vm_contig_grow_cache(tries, low, high);
 				vm_map_lock(map);
 				VM_OBJECT_LOCK(object);
 				goto retry;
@@ -368,7 +371,7 @@ retry:
 	pages = vm_phys_alloc_contig(npgs, low, high, alignment, boundary);
 	if (pages == NULL) {
 		if (tries < ((flags & M_NOWAIT) != 0 ? 1 : 3)) {
-			vm_contig_grow_cache(tries);
+			vm_contig_grow_cache(tries, low, high);
 			tries++;
 			goto retry;
 		}
diff --git a/sys/vm/vm_pageout.h b/sys/vm/vm_pageout.h
index 4759dd7..4857c3e 100644
--- a/sys/vm/vm_pageout.h
+++ b/sys/vm/vm_pageout.h
@@ -105,5 +105,6 @@ boolean_t vm_pageout_fallback_object_lock(vm_page_t, vm_page_t *);
 int vm_pageout_flush(vm_page_t *, int, int);
 void vm_pageout_oom(int shortage);
 boolean_t vm_pageout_page_lock(vm_page_t, vm_page_t *);
+void vm_contig_grow_cache(int, vm_paddr_t, vm_paddr_t);
 #endif
 #endif	/* _VM_VM_PAGEOUT_H_ */