svn commit: r307501 - head/sys/vm

[Konstantin Belousov]

Author: kib
Date: Mon Oct 17 08:17:06 2016
New Revision: 307501
URL: https://svnweb.freebsd.org/changeset/base/307501

Log:
  If vm_fault_hold(9) finds that fs.m is wired, do not free it after a
  pager error, leave the page to the wire owner.  E.g. the page might be
  a part of the invalidated buffer.
  
  Reported and tested by:	pho
  Reviewed by:	alc, markj
  Sponsored by:	The FreeBSD Foundation
  MFC after:	2 weeks
  Differential revision:	https://reviews.freebsd.org/D8197

Modified:
  head/sys/vm/vm_fault.c

Modified: head/sys/vm/vm_fault.c
==============================================================================
--- head/sys/vm/vm_fault.c	Mon Oct 17 08:16:26 2016	(r307500)
+++ head/sys/vm/vm_fault.c	Mon Oct 17 08:17:06 2016	(r307501)
@@ -722,7 +722,10 @@ vnode_locked:
 			 */
 			if (rv == VM_PAGER_ERROR || rv == VM_PAGER_BAD) {
 				vm_page_lock(fs.m);
-				vm_page_free(fs.m);
+				if (fs.m->wire_count == 0)
+					vm_page_free(fs.m);
+				else
+					vm_page_xunbusy_maybelocked(fs.m);
 				vm_page_unlock(fs.m);
 				fs.m = NULL;
 				unlock_and_deallocate(&fs);
@@ -742,7 +745,10 @@ vnode_locked:
 			 */
 			if (fs.object != fs.first_object) {
 				vm_page_lock(fs.m);
-				vm_page_free(fs.m);
+				if (fs.m->wire_count == 0)
+					vm_page_free(fs.m);
+				else
+					vm_page_xunbusy_maybelocked(fs.m);
 				vm_page_unlock(fs.m);
 				fs.m = NULL;
 			}