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Date:      Tue, 29 Oct 2019 20:46:26 +0000 (UTC)
From:      Jeff Roberson <jeff@FreeBSD.org>
To:        src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org
Subject:   svn commit: r354156 - head/sys/vm
Message-ID:  <201910292046.x9TKkQZc030972@repo.freebsd.org>
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Author: jeff
Date: Tue Oct 29 20:46:25 2019
New Revision: 354156
URL: https://svnweb.freebsd.org/changeset/base/354156

Log:
  Drop the object lock earlier in fault and don't relock it after pmap_enter().
  
  Recent changes in object and page locking have enabled more lock pushdown.
  
  Reviewed by:	kib
  Tested by:	pho
  Differential Revision:	https://reviews.freebsd.org/D22036

Modified:
  head/sys/vm/vm_fault.c

Modified: head/sys/vm/vm_fault.c
==============================================================================
--- head/sys/vm/vm_fault.c	Tue Oct 29 20:37:59 2019	(r354155)
+++ head/sys/vm/vm_fault.c	Tue Oct 29 20:46:25 2019	(r354156)
@@ -184,11 +184,10 @@ unlock_vp(struct faultstate *fs)
 }
 
 static void
-unlock_and_deallocate(struct faultstate *fs)
+fault_deallocate(struct faultstate *fs)
 {
 
 	vm_object_pip_wakeup(fs->object);
-	VM_OBJECT_WUNLOCK(fs->object);
 	if (fs->object != fs->first_object) {
 		VM_OBJECT_WLOCK(fs->first_object);
 		vm_page_free(fs->first_m);
@@ -202,6 +201,14 @@ unlock_and_deallocate(struct faultstate *fs)
 }
 
 static void
+unlock_and_deallocate(struct faultstate *fs)
+{
+
+	VM_OBJECT_WUNLOCK(fs->object);
+	fault_deallocate(fs);
+}
+
+static void
 vm_fault_dirty(vm_map_entry_t entry, vm_page_t m, vm_prot_t prot,
     vm_prot_t fault_type, int fault_flags, bool set_wd)
 {
@@ -1261,10 +1268,12 @@ readrest:
 				    fs.object, OFF_TO_IDX(
 				    fs.first_object->backing_object_offset));
 #endif
+				VM_OBJECT_WUNLOCK(fs.object);
 				fs.first_m = fs.m;
 				fs.m = NULL;
 				VM_CNT_INC(v_cow_optim);
 			} else {
+				VM_OBJECT_WUNLOCK(fs.object);
 				/*
 				 * Oh, well, lets copy it.
 				 */
@@ -1285,7 +1294,6 @@ readrest:
 			 * conditional
 			 */
 			vm_object_pip_wakeup(fs.object);
-			VM_OBJECT_WUNLOCK(fs.object);
 
 			/*
 			 * We only try to prefault read-only mappings to the
@@ -1405,7 +1413,6 @@ readrest:
 		vm_fault_prefault(&fs, vaddr,
 		    faultcount > 0 ? behind : PFBAK,
 		    faultcount > 0 ? ahead : PFFOR, false);
-	VM_OBJECT_WLOCK(fs.object);
 
 	/*
 	 * If the page is not wired down, then put it where the pageout daemon
@@ -1427,7 +1434,7 @@ readrest:
 	/*
 	 * Unlock everything, and return
 	 */
-	unlock_and_deallocate(&fs);
+	fault_deallocate(&fs);
 	if (hardfault) {
 		VM_CNT_INC(v_io_faults);
 		curthread->td_ru.ru_majflt++;

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