From daf6353b9fd988e5d35657b1aaf21d5b69ba0c4f Mon Sep 17 00:00:00 2001
From: Justus Winter <4winter@informatik.uni-hamburg.de>
Date: Thu, 20 Aug 2015 13:43:01 +0200
Subject: yyy avoid unlocking while zeroing or copying

---
 vm/vm_fault.c | 22 +++++++++-------------
 1 file changed, 9 insertions(+), 13 deletions(-)

diff --git a/vm/vm_fault.c b/vm/vm_fault.c
index 40d1cbc..1ed9e03 100644
--- a/vm/vm_fault.c
+++ b/vm/vm_fault.c
@@ -462,15 +462,16 @@ vm_fault_return_t vm_fault_page(
 					m = real_m;
 
 					/*
-					 *  Drop the lock while zero filling
-					 *  page.  Then break because this
-					 *  is the page we wanted.  Checking
-					 *  the page lock is a waste of time;
-					 *  this page was either absent or
-					 *  newly allocated -- in both cases
-					 *  it can't be page locked by a pager.
+					 *  Zero fill the page.  Then
+					 *  break because this is the
+					 *  page we wanted.  Checking
+					 *  the page lock is a waste
+					 *  of time; this page was
+					 *  either absent or newly
+					 *  allocated -- in both cases
+					 *  it can't be page locked by
+					 *  a pager.
 					 */
-					vm_object_unlock(object);
 
 					vm_page_zero_fill(m);
 
@@ -478,7 +479,6 @@ vm_fault_return_t vm_fault_page(
 
 					vm_stat.zero_fill_count++;
 					current_task()->zero_fills++;
-					vm_object_lock(object);
 					pmap_clear_modify(m->phys_addr);
 					break;
 				} else {
@@ -755,12 +755,10 @@ vm_fault_return_t vm_fault_page(
 				return(VM_FAULT_MEMORY_SHORTAGE);
 			}
 
-			vm_object_unlock(object);
 			vm_page_zero_fill(m);
 			vm_stat_sample(SAMPLED_PC_VM_ZFILL_FAULTS);
 			vm_stat.zero_fill_count++;
 			current_task()->zero_fills++;
-			vm_object_lock(object);
 			pmap_clear_modify(m->phys_addr);
 			break;
 		}
@@ -841,9 +839,7 @@ vm_fault_return_t vm_fault_page(
 				return(VM_FAULT_MEMORY_SHORTAGE);
 			}
 
-			vm_object_unlock(object);
 			vm_page_copy(m, copy_m);
-			vm_object_lock(object);
 
 			/*
 			 *	If another map is truly sharing this
-- 
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