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From: Alan Cox <alc@FreeBSD.org>
Date: Sun, 5 Apr 2015 20:07:34 +0000 (UTC)
To: src-committers@freebsd.org, svn-src-all@freebsd.org,
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Subject: svn commit: r281118 - head/sys/vm
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Author: alc
Date: Sun Apr  5 20:07:33 2015
New Revision: 281118
URL: https://svnweb.freebsd.org/changeset/base/281118

Log:
  Until the lock assertions in vm_page_advise() are properly reevaluated,
  vm_fault_dontneed() should acquire a write lock on the first object in
  the shadow chain.
  
  Reported by:	gleb, David Wolfskill

Modified:
  head/sys/vm/vm_fault.c

Modified: head/sys/vm/vm_fault.c
==============================================================================
--- head/sys/vm/vm_fault.c	Sun Apr  5 18:57:58 2015	(r281117)
+++ head/sys/vm/vm_fault.c	Sun Apr  5 20:07:33 2015	(r281118)
@@ -1060,9 +1060,9 @@ vm_fault_dontneed(const struct faultstat
 	VM_OBJECT_ASSERT_WLOCKED(object);
 	first_object = fs->first_object;
 	if (first_object != object) {
-		if (!VM_OBJECT_TRYRLOCK(first_object)) {
+		if (!VM_OBJECT_TRYWLOCK(first_object)) {
 			VM_OBJECT_WUNLOCK(object);
-			VM_OBJECT_RLOCK(first_object);
+			VM_OBJECT_WLOCK(first_object);
 			VM_OBJECT_WLOCK(object);
 		}
 	}
@@ -1097,7 +1097,7 @@ vm_fault_dontneed(const struct faultstat
 		}
 	}
 	if (first_object != object)
-		VM_OBJECT_RUNLOCK(first_object);
+		VM_OBJECT_WUNLOCK(first_object);
 }
 
 /*