From a278a7945d7d846d7c2e2c14e8a09a62604756b8 Mon Sep 17 00:00:00 2001
From: tedu <tedu@openbsd.org>
Date: Thu, 15 Jul 2010 00:14:17 +0000
Subject: [PATCH] the uvm_km_putpage is calling into tangly uvm guts again on
 not pmap direct. go back to something more like the previous design, and have
 the thread do the heavy lifting.  solves vmmaplk panics. ok deraadt oga thib
 [and even simple diffs are hard to get perfect. help from mdempsky and
 deraadt]

---
 sys/uvm/uvm_km.c | 78 +++++++++++++++++++++++++++++++++++-------------
 sys/uvm/uvm_km.h |  8 ++++-
 2 files changed, 64 insertions(+), 22 deletions(-)

diff --git a/sys/uvm/uvm_km.c b/sys/uvm/uvm_km.c
index 64b3f0be812..aee736d2e66 100644
--- a/sys/uvm/uvm_km.c
+++ b/sys/uvm/uvm_km.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: uvm_km.c,v 1.83 2010/07/02 23:12:38 thib Exp $	*/
+/*	$OpenBSD: uvm_km.c,v 1.84 2010/07/15 00:14:17 tedu Exp $	*/
 /*	$NetBSD: uvm_km.c,v 1.42 2001/01/14 02:10:01 thorpej Exp $	*/
 
 /* 
@@ -707,6 +707,7 @@ struct uvm_km_pages uvm_km_pages;
 
 void uvm_km_createthread(void *);
 void uvm_km_thread(void *);
+struct uvm_km_free_page *uvm_km_doputpage(struct uvm_km_free_page *);
 
 /*
  * Allocate the initial reserve, and create the thread which will
@@ -768,34 +769,47 @@ uvm_km_thread(void *arg)
 {
 	vaddr_t pg[16];
 	int i;
+	int allocmore = 0;
+	struct uvm_km_free_page *fp = NULL;
 
 	for (;;) {
 		mtx_enter(&uvm_km_pages.mtx);
-		if (uvm_km_pages.free >= uvm_km_pages.lowat) {
+		if (uvm_km_pages.free >= uvm_km_pages.lowat &&
+		    uvm_km_pages.freelist == NULL) {
 			msleep(&uvm_km_pages.km_proc, &uvm_km_pages.mtx,
 			    PVM, "kmalloc", 0);
 		}
+		allocmore = uvm_km_pages.free < uvm_km_pages.lowat;
+		fp = uvm_km_pages.freelist;
+		uvm_km_pages.freelist = NULL;
+		uvm_km_pages.freelistlen = 0;
 		mtx_leave(&uvm_km_pages.mtx);
 
-		for (i = 0; i < nitems(pg); i++) {
-			pg[i] = (vaddr_t)uvm_km_kmemalloc(kernel_map, NULL,
-			    PAGE_SIZE, UVM_KMF_VALLOC);
-		}
+		if (allocmore) {
+			for (i = 0; i < nitems(pg); i++) {
+				pg[i] = (vaddr_t)uvm_km_kmemalloc(kernel_map,
+				    NULL, PAGE_SIZE, UVM_KMF_VALLOC);
+			}
+	
+			mtx_enter(&uvm_km_pages.mtx);
+			for (i = 0; i < nitems(pg); i++) {
+				if (uvm_km_pages.free ==
+				    nitems(uvm_km_pages.page))
+					break;
+				else
+					uvm_km_pages.page[uvm_km_pages.free++]
+					    = pg[i];
+			}
+			wakeup(&uvm_km_pages.free);
+			mtx_leave(&uvm_km_pages.mtx);
 
-		mtx_enter(&uvm_km_pages.mtx);
-		for (i = 0; i < nitems(pg); i++) {
-			if (uvm_km_pages.free == nitems(uvm_km_pages.page))
-				break;
-			else
-				uvm_km_pages.page[uvm_km_pages.free++] = pg[i];
+			/* Cleanup left-over pages (if any). */
+			for (; i < nitems(pg); i++)
+				uvm_km_free(kernel_map, pg[i], PAGE_SIZE);
+		}
+		while (fp) {
+			fp = uvm_km_doputpage(fp);
 		}
-
-		wakeup(&uvm_km_pages.free);
-		mtx_leave(&uvm_km_pages.mtx);
-
-		/* Cleanup left-over pages (if any). */
-		for (; i < nitems(pg); i++)
-			uvm_km_free(kernel_map, pg[i], PAGE_SIZE);
 	}
 }
 #endif
@@ -860,14 +874,35 @@ uvm_km_getpage_pla(int flags, int *slowdown, paddr_t low, paddr_t high,
 void
 uvm_km_putpage(void *v)
 {
+#ifdef __HAVE_PMAP_DIRECT
 	vaddr_t va = (vaddr_t)v;
 	struct vm_page *pg;
 
-#ifdef __HAVE_PMAP_DIRECT
 	pg = pmap_unmap_direct(va);
+
+	uvm_pagefree(pg);
 #else	/* !__HAVE_PMAP_DIRECT */
+	struct uvm_km_free_page *fp = v;
+
+	mtx_enter(&uvm_km_pages.mtx);
+	fp->next = uvm_km_pages.freelist;
+	uvm_km_pages.freelist = fp;
+	if (uvm_km_pages.freelistlen++ > 16)
+		wakeup(&uvm_km_pages.km_proc);
+	mtx_leave(&uvm_km_pages.mtx);
+#endif	/* !__HAVE_PMAP_DIRECT */
+}
+
+#ifndef __HAVE_PMAP_DIRECT
+struct uvm_km_free_page *
+uvm_km_doputpage(struct uvm_km_free_page *fp)
+{
+	vaddr_t va = (vaddr_t)fp;
+	struct vm_page *pg;
 	int	freeva = 1;
 	paddr_t pa;
+	struct uvm_km_free_page *nextfp = fp->next;
+
 	if (!pmap_extract(pmap_kernel(), va, &pa))
 		panic("lost pa");
 	pg = PHYS_TO_VM_PAGE(pa);
@@ -886,7 +921,8 @@ uvm_km_putpage(void *v)
 
 	if (freeva)
 		uvm_km_free(kernel_map, va, PAGE_SIZE);
-#endif	/* !__HAVE_PMAP_DIRECT */
 
 	uvm_pagefree(pg);
+	return (nextfp);
 }
+#endif	/* !__HAVE_PMAP_DIRECT */
diff --git a/sys/uvm/uvm_km.h b/sys/uvm/uvm_km.h
index b14f2e66280..76a2ce95720 100644
--- a/sys/uvm/uvm_km.h
+++ b/sys/uvm/uvm_km.h
@@ -1,4 +1,4 @@
-/*	$OpenBSD: uvm_km.h,v 1.10 2010/06/28 04:20:29 miod Exp $	*/
+/*	$OpenBSD: uvm_km.h,v 1.11 2010/07/15 00:14:17 tedu Exp $	*/
 /*	$NetBSD: uvm_km.h,v 1.9 1999/06/21 17:25:11 thorpej Exp $	*/
 
 /*
@@ -58,6 +58,9 @@ void uvm_km_pgremove_intrsafe(vaddr_t, vaddr_t);
 #define UVM_KM_PAGES_LOWAT_MAX	(2048)
 #define UVM_KM_PAGES_HIWAT_MAX	(4 * UVM_KM_PAGES_LOWAT_MAX)
 
+struct uvm_km_free_page {
+	struct uvm_km_free_page *next;
+};
 struct uvm_km_pages {
 	struct	mutex mtx;
 
@@ -69,6 +72,9 @@ struct uvm_km_pages {
 	int	free;
 	vaddr_t	page[UVM_KM_PAGES_HIWAT_MAX];
 
+	struct uvm_km_free_page *freelist;
+	int freelistlen;
+
 	struct	proc *km_proc;
 };
 
-- 
2.20.1