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Date:      Mon, 20 Jun 2016 09:15:03 +0000 (UTC)
From:      Konstantin Belousov <kib@FreeBSD.org>
To:        src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-stable@freebsd.org, svn-src-stable-10@freebsd.org
Subject:   svn commit: r302028 - stable/10/sys/amd64/amd64
Message-ID:  <201606200915.u5K9F3Yf037188@repo.freebsd.org>
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Author: kib
Date: Mon Jun 20 09:15:03 2016
New Revision: 302028
URL: https://svnweb.freebsd.org/changeset/base/302028

Log:
  MFC r301853:
  Do not access pv_table array for fictitious pages.

Modified:
  stable/10/sys/amd64/amd64/pmap.c
Directory Properties:
  stable/10/   (props changed)

Modified: stable/10/sys/amd64/amd64/pmap.c
==============================================================================
--- stable/10/sys/amd64/amd64/pmap.c	Mon Jun 20 09:06:50 2016	(r302027)
+++ stable/10/sys/amd64/amd64/pmap.c	Mon Jun 20 09:15:03 2016	(r302028)
@@ -381,6 +381,7 @@ static TAILQ_HEAD(pch, pv_chunk) pv_chun
 static struct mtx pv_chunks_mutex;
 static struct rwlock pv_list_locks[NPV_LIST_LOCKS];
 static struct md_page *pv_table;
+static struct md_page pv_dummy;
 
 /*
  * All those kernel PT submaps that BSD is so fond of
@@ -1100,6 +1101,7 @@ pmap_init(void)
 	    M_WAITOK | M_ZERO);
 	for (i = 0; i < pv_npg; i++)
 		TAILQ_INIT(&pv_table[i].pv_list);
+	TAILQ_INIT(&pv_dummy.pv_list);
 
 	mtx_init(&cpage_lock, "cpage", NULL, MTX_DEF);
 	cpage_a = kva_alloc(PAGE_SIZE);
@@ -3808,9 +3810,8 @@ pmap_remove_all(vm_page_t m)
 	    ("pmap_remove_all: page %p is not managed", m));
 	SLIST_INIT(&free);
 	rw_wlock(&pvh_global_lock);
-	if ((m->flags & PG_FICTITIOUS) != 0)
-		goto small_mappings;
-	pvh = pa_to_pvh(VM_PAGE_TO_PHYS(m));
+	pvh = (m->flags & PG_FICTITIOUS) != 0 ? &pv_dummy :
+	    pa_to_pvh(VM_PAGE_TO_PHYS(m));
 	while ((pv = TAILQ_FIRST(&pvh->pv_list)) != NULL) {
 		pmap = PV_PMAP(pv);
 		PMAP_LOCK(pmap);
@@ -3819,7 +3820,6 @@ pmap_remove_all(vm_page_t m)
 		(void)pmap_demote_pde(pmap, pde, va);
 		PMAP_UNLOCK(pmap);
 	}
-small_mappings:
 	while ((pv = TAILQ_FIRST(&m->md.pv_list)) != NULL) {
 		pmap = PV_PMAP(pv);
 		PMAP_LOCK(pmap);
@@ -5677,11 +5677,10 @@ pmap_remove_write(vm_page_t m)
 		return;
 	rw_rlock(&pvh_global_lock);
 	lock = VM_PAGE_TO_PV_LIST_LOCK(m);
-	pvh = pa_to_pvh(VM_PAGE_TO_PHYS(m));
+	pvh = (m->flags & PG_FICTITIOUS) != 0 ? &pv_dummy :
+	    pa_to_pvh(VM_PAGE_TO_PHYS(m));
 retry_pv_loop:
 	rw_wlock(lock);
-	if ((m->flags & PG_FICTITIOUS) != 0)
-		goto small_mappings;
 	TAILQ_FOREACH_SAFE(pv, &pvh->pv_list, pv_next, next_pv) {
 		pmap = PV_PMAP(pv);
 		if (!PMAP_TRYLOCK(pmap)) {
@@ -5705,7 +5704,6 @@ retry_pv_loop:
 		    lock, VM_PAGE_TO_PV_LIST_LOCK(m), m));
 		PMAP_UNLOCK(pmap);
 	}
-small_mappings:
 	TAILQ_FOREACH(pv, &m->md.pv_list, pv_next) {
 		pmap = PV_PMAP(pv);
 		if (!PMAP_TRYLOCK(pmap)) {
@@ -5807,13 +5805,12 @@ pmap_ts_referenced(vm_page_t m)
 	cleared = 0;
 	pa = VM_PAGE_TO_PHYS(m);
 	lock = PHYS_TO_PV_LIST_LOCK(pa);
-	pvh = pa_to_pvh(pa);
+	pvh = (m->flags & PG_FICTITIOUS) != 0 ? &pv_dummy : pa_to_pvh(pa);
 	rw_rlock(&pvh_global_lock);
 	rw_wlock(lock);
 retry:
 	not_cleared = 0;
-	if ((m->flags & PG_FICTITIOUS) != 0 ||
-	    (pvf = TAILQ_FIRST(&pvh->pv_list)) == NULL)
+	if ((pvf = TAILQ_FIRST(&pvh->pv_list)) == NULL)
 		goto small_mappings;
 	pv = pvf;
 	do {
@@ -6139,13 +6136,12 @@ pmap_clear_modify(vm_page_t m)
 	 */
 	if ((m->aflags & PGA_WRITEABLE) == 0)
 		return;
-	pvh = pa_to_pvh(VM_PAGE_TO_PHYS(m));
+	pvh = (m->flags & PG_FICTITIOUS) != 0 ? &pv_dummy :
+	    pa_to_pvh(VM_PAGE_TO_PHYS(m));
 	rw_rlock(&pvh_global_lock);
 	lock = VM_PAGE_TO_PV_LIST_LOCK(m);
 	rw_wlock(lock);
 restart:
-	if ((m->flags & PG_FICTITIOUS) != 0)
-		goto small_mappings;
 	TAILQ_FOREACH_SAFE(pv, &pvh->pv_list, pv_next, next_pv) {
 		pmap = PV_PMAP(pv);
 		if (!PMAP_TRYLOCK(pmap)) {
@@ -6189,7 +6185,6 @@ restart:
 		}
 		PMAP_UNLOCK(pmap);
 	}
-small_mappings:
 	TAILQ_FOREACH(pv, &m->md.pv_list, pv_next) {
 		pmap = PV_PMAP(pv);
 		if (!PMAP_TRYLOCK(pmap)) {

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