svn commit: r237803 - stable/9/sys/vm

Author: jhb
Date: Fri Jun 29 17:12:03 2012
New Revision: 237803
URL: http://svn.freebsd.org/changeset/base/237803

Log:
  MFC 237334:
  Move the per-thread deferred user map entries list into a private list
  in vm_map_process_deferred() which is then iterated to release map entries.
  This avoids having a nested vm map unlock operation called from the loop
  body attempt to recuse into vm_map_process_deferred().  This can happen if
  the vm_map_remove() triggers the OOM killer.

Modified:
  stable/9/sys/vm/vm_map.c
Directory Properties:
  stable/9/sys/   (props changed)
  stable/9/sys/amd64/include/xen/   (props changed)
  stable/9/sys/boot/   (props changed)
  stable/9/sys/boot/i386/efi/   (props changed)
  stable/9/sys/boot/ia64/efi/   (props changed)
  stable/9/sys/boot/ia64/ski/   (props changed)
  stable/9/sys/boot/powerpc/boot1.chrp/   (props changed)
  stable/9/sys/boot/powerpc/ofw/   (props changed)
  stable/9/sys/cddl/contrib/opensolaris/   (props changed)
  stable/9/sys/conf/   (props changed)
  stable/9/sys/contrib/dev/acpica/   (props changed)
  stable/9/sys/contrib/octeon-sdk/   (props changed)
  stable/9/sys/contrib/pf/   (props changed)
  stable/9/sys/contrib/x86emu/   (props changed)
  stable/9/sys/dev/   (props changed)
  stable/9/sys/dev/e1000/   (props changed)
  stable/9/sys/dev/isp/   (props changed)
  stable/9/sys/dev/ixgbe/   (props changed)
  stable/9/sys/fs/   (props changed)
  stable/9/sys/fs/ntfs/   (props changed)
  stable/9/sys/modules/   (props changed)

Modified: stable/9/sys/vm/vm_map.c
==============================================================================
--- stable/9/sys/vm/vm_map.c	Fri Jun 29 17:05:13 2012	(r237802)
+++ stable/9/sys/vm/vm_map.c	Fri Jun 29 17:12:03 2012	(r237803)
@@ -475,12 +475,14 @@ static void
 vm_map_process_deferred(void)
 {
 	struct thread *td;
-	vm_map_entry_t entry;
+	vm_map_entry_t entry, next;
 	vm_object_t object;
 
 	td = curthread;
-	while ((entry = td->td_map_def_user) != NULL) {
-		td->td_map_def_user = entry->next;
+	entry = td->td_map_def_user;
+	td->td_map_def_user = NULL;
+	while (entry != NULL) {
+		next = entry->next;
 		if ((entry->eflags & MAP_ENTRY_VN_WRITECNT) != 0) {
 			/*
 			 * Decrement the object's writemappings and
@@ -494,6 +496,7 @@ vm_map_process_deferred(void)
 			    entry->end);
 		}
 		vm_map_entry_deallocate(entry, FALSE);
+		entry = next;
 	}
 }
 
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