From: mpi <mpi@openbsd.org>
Date: Thu, 4 Mar 2021 09:00:03 +0000 (+0000)
Subject: Modify `uvmexp.swpgonly' atomically, required for uvm_fault() w/o KERNEL_LOCK()
X-Git-Url: http://artulab.com/gitweb/?a=commitdiff_plain;h=c4a864ba38a189859dcf0af4cf9fb01aabd6a92c;p=openbsd

Modify `uvmexp.swpgonly' atomically, required for uvm_fault() w/o KERNEL_LOCK()

ok kettenis@
---

diff --git a/sys/uvm/uvm_anon.c b/sys/uvm/uvm_anon.c
index b64321410da..2ae8dacc482 100644
--- a/sys/uvm/uvm_anon.c
+++ b/sys/uvm/uvm_anon.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: uvm_anon.c,v 1.51 2021/01/19 13:21:36 mpi Exp $	*/
+/*	$OpenBSD: uvm_anon.c,v 1.52 2021/03/04 09:00:03 mpi Exp $	*/
 /*	$NetBSD: uvm_anon.c,v 1.10 2000/11/25 06:27:59 chs Exp $	*/
 
 /*
@@ -120,9 +120,9 @@ uvm_anfree_list(struct vm_anon *anon, struct pglist *pgl)
 		}
 	} else {
 		if (anon->an_swslot != 0) {
-			/* this page is no longer only in swap. */
+			/* This page is no longer only in swap. */
 			KASSERT(uvmexp.swpgonly > 0);
-			uvmexp.swpgonly--;
+			atomic_dec_int(&uvmexp.swpgonly);
 		}
 	}
 	anon->an_lock = NULL;
diff --git a/sys/uvm/uvm_aobj.c b/sys/uvm/uvm_aobj.c
index 5567ec9773a..d6f0b8cb597 100644
--- a/sys/uvm/uvm_aobj.c
+++ b/sys/uvm/uvm_aobj.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: uvm_aobj.c,v 1.90 2021/01/11 18:51:09 mpi Exp $	*/
+/*	$OpenBSD: uvm_aobj.c,v 1.91 2021/03/04 09:00:03 mpi Exp $	*/
 /*	$NetBSD: uvm_aobj.c,v 1.39 2001/02/18 21:19:08 chs Exp $	*/
 
 /*
@@ -381,7 +381,7 @@ uao_free(struct uvm_aobj *aobj)
 					 * this page is no longer
 					 * only in swap.
 					 */
-					uvmexp.swpgonly--;
+					atomic_dec_int(&uvmexp.swpgonly);
 				}
 
 				next = LIST_NEXT(elt, list);
@@ -400,7 +400,7 @@ uao_free(struct uvm_aobj *aobj)
 			if (slot) {
 				uvm_swap_free(slot, 1);
 				/* this page is no longer only in swap. */
-				uvmexp.swpgonly--;
+				atomic_dec_int(&uvmexp.swpgonly);
 			}
 		}
 		free(aobj->u_swslots, M_UVMAOBJ, aobj->u_pages * sizeof(int));
@@ -1549,6 +1549,6 @@ uao_dropswap_range(struct uvm_object *uobj, voff_t start, voff_t end)
 	 */
 	if (swpgonlydelta > 0) {
 		KASSERT(uvmexp.swpgonly >= swpgonlydelta);
-		uvmexp.swpgonly -= swpgonlydelta;
+		atomic_add_int(&uvmexp.swpgonly, -swpgonlydelta);
 	}
 }
diff --git a/sys/uvm/uvm_km.c b/sys/uvm/uvm_km.c
index 1b8c1857f27..ba39b274d10 100644
--- a/sys/uvm/uvm_km.c
+++ b/sys/uvm/uvm_km.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: uvm_km.c,v 1.139 2020/12/15 22:14:42 mpi Exp $	*/
+/*	$OpenBSD: uvm_km.c,v 1.140 2021/03/04 09:00:03 mpi Exp $	*/
 /*	$NetBSD: uvm_km.c,v 1.42 2001/01/14 02:10:01 thorpej Exp $	*/
 
 /* 
@@ -242,6 +242,7 @@ uvm_km_pgremove(struct uvm_object *uobj, vaddr_t start, vaddr_t end)
 	struct vm_page *pp;
 	voff_t curoff;
 	int slot;
+	int swpgonlydelta = 0;
 
 	KASSERT(uobj->pgops == &aobj_pager);
 
@@ -262,9 +263,14 @@ uvm_km_pgremove(struct uvm_object *uobj, vaddr_t start, vaddr_t end)
 			uvm_pagefree(pp);
 			uvm_unlock_pageq();
 		} else if (slot != 0) {
-			uvmexp.swpgonly--;
+			swpgonlydelta++;
 		}
 	}
+
+	if (swpgonlydelta > 0) {
+		KASSERT(uvmexp.swpgonly >= swpgonlydelta);
+		atomic_add_int(&uvmexp.swpgonly, -swpgonlydelta);
+	}
 }
 
 
diff --git a/sys/uvm/uvm_pdaemon.c b/sys/uvm/uvm_pdaemon.c
index 5892059354a..875e82056cc 100644
--- a/sys/uvm/uvm_pdaemon.c
+++ b/sys/uvm/uvm_pdaemon.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: uvm_pdaemon.c,v 1.89 2021/03/01 09:13:33 mpi Exp $	*/
+/*	$OpenBSD: uvm_pdaemon.c,v 1.90 2021/03/04 09:00:03 mpi Exp $	*/
 /*	$NetBSD: uvm_pdaemon.c,v 1.23 2000/08/20 10:24:14 bjh21 Exp $	*/
 
 /* 
@@ -491,7 +491,7 @@ uvmpd_scan_inactive(struct pglist *pglst)
 			if (p->pg_flags & PG_CLEAN) {
 				if (p->pg_flags & PQ_SWAPBACKED) {
 					/* this page now lives only in swap */
-					uvmexp.swpgonly++;
+					atomic_inc_int(&uvmexp.swpgonly);
 				}
 
 				/* zap all mappings with pmap_page_protect... */
@@ -994,7 +994,7 @@ uvmpd_drop(struct pglist *pglst)
 			if (p->pg_flags & PG_CLEAN) {
 				if (p->pg_flags & PQ_SWAPBACKED) {
 					/* this page now lives only in swap */
-					uvmexp.swpgonly++;
+					atomic_inc_int(&uvmexp.swpgonly);
 				}
 
 				/* zap all mappings with pmap_page_protect... */
diff --git a/sys/uvm/uvm_swap.c b/sys/uvm/uvm_swap.c
index 0b5aa3191c2..cc9786e482e 100644
--- a/sys/uvm/uvm_swap.c
+++ b/sys/uvm/uvm_swap.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: uvm_swap.c,v 1.148 2020/12/14 13:29:18 mpi Exp $	*/
+/*	$OpenBSD: uvm_swap.c,v 1.149 2021/03/04 09:00:03 mpi Exp $	*/
 /*	$NetBSD: uvm_swap.c,v 1.40 2000/11/17 11:39:39 mrg Exp $	*/
 
 /*
@@ -1574,14 +1574,14 @@ uvm_swap_get(struct vm_page *page, int swslot, int flags)
 
 	KERNEL_LOCK();
 	/* this page is (about to be) no longer only in swap. */
-	uvmexp.swpgonly--;
+	atomic_dec_int(&uvmexp.swpgonly);
 
 	result = uvm_swap_io(&page, swslot, 1, B_READ |
 	    ((flags & PGO_SYNCIO) ? 0 : B_ASYNC));
 
 	if (result != VM_PAGER_OK && result != VM_PAGER_PEND) {
 		/* oops, the read failed so it really is still only in swap. */
-		uvmexp.swpgonly++;
+		atomic_inc_int(&uvmexp.swpgonly);
 	}
 	KERNEL_UNLOCK();
 	return (result);
diff --git a/sys/uvm/uvmexp.h b/sys/uvm/uvmexp.h
index 0e3129e3513..90533813dff 100644
--- a/sys/uvm/uvmexp.h
+++ b/sys/uvm/uvmexp.h
@@ -1,4 +1,4 @@
-/*	$OpenBSD: uvmexp.h,v 1.8 2020/12/28 14:01:23 mpi Exp $	*/
+/*	$OpenBSD: uvmexp.h,v 1.9 2021/03/04 09:00:03 mpi Exp $	*/
 
 #ifndef	_UVM_UVMEXP_
 #define	_UVM_UVMEXP_
@@ -41,6 +41,7 @@
  * other than the vm system.
  *
  *  Locks used to protect struct members in this file:
+ *	a	atomic operations
  *	I	immutable after creation
  *	K	kernel lock
  *	F	uvm_lock_fpageq
@@ -82,7 +83,7 @@ struct uvmexp {
 	int nswapdev;	/* number of configured swap devices in system */
 	int swpages;	/* [K] number of PAGE_SIZE'ed swap pages */
 	int swpginuse;	/* number of swap pages in use */
-	int swpgonly;	/* [K] number of swap pages in use, not also in RAM */
+	int swpgonly;	/* [a] number of swap pages in use, not also in RAM */
 	int nswget;	/* number of swap pages moved from disk to RAM */
 	int nanon;	/* XXX number total of anon's in system */
 	int unused05;	/* formerly nanonneeded */