a better fix for the "uvm_km thread runs out of memory" problem.

add a new arg to the backend so it can tell pool to slow down.  when we get
this flag, yield *after* putting the page in the pool's free list.  whatever
we do, don't let the thread sleep.

this makes things better by still letting the thread run when a huge pf
request comes in, but without artificially increasing pressure on the backend
by eating pages without feeding them forward.

ok deraadt

4 files changed, 22 insertions, 17 deletions

diff --git a/sys/arch/alpha/alpha/pmap.c b/sys/arch/alpha/alpha/pmap.c
index 21e931730df..255a9a19dd6 100644
--- a/sys/arch/alpha/alpha/pmap.c
+++ b/sys/arch/alpha/alpha/pmap.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: pmap.c,v 1.57 2008/09/12 12:27:26 blambert Exp $ */
+/* $OpenBSD: pmap.c,v 1.58 2008/10/23 23:54:02 tedu Exp $ */
 /* $NetBSD: pmap.c,v 1.154 2000/12/07 22:18:55 thorpej Exp $ */
 
 /*-
@@ -451,7 +451,7 @@ void	pmap_l3pt_delref(pmap_t, vaddr_t, pt_entry_t *, cpuid_t,
 void	pmap_l2pt_delref(pmap_t, pt_entry_t *, pt_entry_t *, cpuid_t);
 void	pmap_l1pt_delref(pmap_t, pt_entry_t *, cpuid_t);
 
-void	*pmap_l1pt_alloc(struct pool *, int);
+void	*pmap_l1pt_alloc(struct pool *, int, int *);
 void	pmap_l1pt_free(struct pool *, void *);
 
 struct pool_allocator pmap_l1pt_allocator = {
@@ -468,7 +468,7 @@ void	pmap_pv_remove(pmap_t, paddr_t, vaddr_t, boolean_t,
 	    struct pv_entry **);
 struct	pv_entry *pmap_pv_alloc(void);
 void	pmap_pv_free(struct pv_entry *);
-void	*pmap_pv_page_alloc(struct pool *, int);
+void	*pmap_pv_page_alloc(struct pool *, int, int *);
 void	pmap_pv_page_free(struct pool *, void *);
 struct pool_allocator pmap_pv_allocator = {
 	pmap_pv_page_alloc, pmap_pv_page_free, 0,
@@ -3159,10 +3159,11 @@ pmap_pv_free(struct pv_entry *pv)
  *	Allocate a page for the pv_entry pool.
  */
 void *
-pmap_pv_page_alloc(struct pool *pp, int flags)
+pmap_pv_page_alloc(struct pool *pp, int flags, int *slowdown)
 {
 	paddr_t pg;
 
+	*slowdown = 0;
 	if (pmap_physpage_alloc(PGU_PVENT, &pg))
 		return ((void *)ALPHA_PHYS_TO_K0SEG(pg));
 	return (NULL);
@@ -3558,13 +3559,14 @@ pmap_l1pt_ctor(void *arg, void *object, int flags)
  *	Page allocator for L1 PT pages.
  */
 void *
-pmap_l1pt_alloc(struct pool *pp, int flags)
+pmap_l1pt_alloc(struct pool *pp, int flags, int *slowdown)
 {
 	paddr_t ptpa;
 
 	/*
 	 * Attempt to allocate a free page.
 	 */
+	*slowdown = 0;
 	if (pmap_physpage_alloc(PGU_L1PT, &ptpa) == FALSE)
 		return (NULL);
 
diff --git a/sys/arch/arm/arm/pmap.c b/sys/arch/arm/arm/pmap.c
index 7f81a98e094..ba43c9042fe 100644
--- a/sys/arch/arm/arm/pmap.c
+++ b/sys/arch/arm/arm/pmap.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: pmap.c,v 1.17 2008/06/27 06:03:08 ray Exp $	*/
+/*	$OpenBSD: pmap.c,v 1.18 2008/10/23 23:54:02 tedu Exp $	*/
 /*	$NetBSD: pmap.c,v 1.147 2004/01/18 13:03:50 scw Exp $	*/
 
 /*
@@ -262,7 +262,7 @@ static LIST_HEAD(, pmap) pmap_pmaps;
  * Pool of PV structures
  */
 static struct pool pmap_pv_pool;
-void *pmap_bootstrap_pv_page_alloc(struct pool *, int);
+void *pmap_bootstrap_pv_page_alloc(struct pool *, int, int *);
 void pmap_bootstrap_pv_page_free(struct pool *, void *);
 struct pool_allocator pmap_bootstrap_pv_allocator = {
 	pmap_bootstrap_pv_page_alloc, pmap_bootstrap_pv_page_free
@@ -4055,14 +4055,15 @@ static vaddr_t last_bootstrap_page = 0;
 static void *free_bootstrap_pages = NULL;
 
 void *
-pmap_bootstrap_pv_page_alloc(struct pool *pp, int flags)
+pmap_bootstrap_pv_page_alloc(struct pool *pp, int flags, int *slowdown)
 {
-	extern void *pool_page_alloc(struct pool *, int);
+	extern void *pool_page_alloc(struct pool *, int, int *);
 	vaddr_t new_page;
 	void *rv;
 
 	if (pmap_initialized)
-		return (pool_page_alloc(pp, flags));
+		return (pool_page_alloc(pp, flags, slowdown));
+	*slowdown = 0;
 
 	if (free_bootstrap_pages) {
 		rv = free_bootstrap_pages;
diff --git a/sys/arch/sh/sh/pmap.c b/sys/arch/sh/sh/pmap.c
index bc9b7e4a7bc..649293d0f14 100644
--- a/sys/arch/sh/sh/pmap.c
+++ b/sys/arch/sh/sh/pmap.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: pmap.c,v 1.10 2008/09/12 12:27:27 blambert Exp $	*/
+/*	$OpenBSD: pmap.c,v 1.11 2008/10/23 23:54:02 tedu Exp $	*/
 /*	$NetBSD: pmap.c,v 1.55 2006/08/07 23:19:36 tsutsui Exp $	*/
 
 /*-
@@ -72,7 +72,7 @@ struct pv_entry {
 #define	__pmap_pv_free(pv)	pool_put(&__pmap_pv_pool, (pv))
 STATIC void __pmap_pv_enter(pmap_t, struct vm_page *, vaddr_t, vm_prot_t);
 STATIC void __pmap_pv_remove(pmap_t, struct vm_page *, vaddr_t);
-STATIC void *__pmap_pv_page_alloc(struct pool *, int);
+STATIC void *__pmap_pv_page_alloc(struct pool *, int, int *);
 STATIC void __pmap_pv_page_free(struct pool *, void *);
 STATIC struct pool __pmap_pv_pool;
 STATIC struct pool_allocator pmap_pv_page_allocator = {
@@ -899,14 +899,15 @@ pmap_prefer(vaddr_t foff, vaddr_t *vap)
 
 /*
  * pv_entry pool allocator:
- *	void *__pmap_pv_page_alloc(struct pool *pool, int flags):
+ *	void *__pmap_pv_page_alloc(struct pool *pool, int flags, int *slowdown):
  *	void __pmap_pv_page_free(struct pool *pool, void *v):
  */
 void *
-__pmap_pv_page_alloc(struct pool *pool, int flags)
+__pmap_pv_page_alloc(struct pool *pool, int flags, int *slowdown)
 {
 	struct vm_page *pg;
 
+	*slowdown = 0;
 	pg = uvm_pagealloc(NULL, 0, NULL, UVM_PGA_USERESERVE);
 	if (pg == NULL)
 		return (NULL);
diff --git a/sys/arch/sparc/sparc/pmap.c b/sys/arch/sparc/sparc/pmap.c
index 1a3e4fab3df..b800dacdce5 100644
--- a/sys/arch/sparc/sparc/pmap.c
+++ b/sys/arch/sparc/sparc/pmap.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: pmap.c,v 1.149 2008/06/09 20:31:47 miod Exp $	*/
+/*	$OpenBSD: pmap.c,v 1.150 2008/10/23 23:54:02 tedu Exp $	*/
 /*	$NetBSD: pmap.c,v 1.118 1998/05/19 19:00:18 thorpej Exp $ */
 
 /*
@@ -193,7 +193,7 @@ struct pool pvpool;
  */
 static struct pool L1_pool;
 static struct pool L23_pool;
-void *pgt_page_alloc(struct pool *, int);
+void *pgt_page_alloc(struct pool *, int, int *);
 void  pgt_page_free(struct pool *, void *);
 
 struct pool_allocator pgt_allocator = {
@@ -216,10 +216,11 @@ pcache_flush(va, pa, n)
  * Page table pool back-end.
  */
 void *
-pgt_page_alloc(struct pool *pp, int flags)
+pgt_page_alloc(struct pool *pp, int flags, int *slowdown)
 {
         caddr_t p;
 
+	*slowdown = 0;
         p = (caddr_t)uvm_km_kmemalloc(kernel_map, uvm.kernel_object,
                                       PAGE_SIZE, UVM_KMF_NOWAIT);
         if (p != NULL && ((cpuinfo.flags & CPUFLG_CACHEPAGETABLES) == 0)) {