svn commit: r363607 - head/sys/vm

[Mark Johnston]

Author: markj
Date: Mon Jul 27 14:25:10 2020
New Revision: 363607
URL: https://svnweb.freebsd.org/changeset/base/363607

Log:
  vm_page_free_invalid(): Relax the xbusy assertion.
  
  vm_page_assert_xbusied() asserts that the busying thread is the current
  thread.  For some uses of vm_page_free_invalid() (e.g., error handling
  in vnode_pager_generic_getpages_done()), this condition might not hold.
  
  Reported by:	Jenkins via trasz
  Reviewed by:	chs, kib
  Sponsored by:	The FreeBSD Foundation
  Differential Revision:	https://reviews.freebsd.org/D25828

Modified:
  head/sys/vm/vm_page.c

Modified: head/sys/vm/vm_page.c
==============================================================================
--- head/sys/vm/vm_page.c	Mon Jul 27 14:16:27 2020	(r363606)
+++ head/sys/vm/vm_page.c	Mon Jul 27 14:25:10 2020	(r363607)
@@ -1371,9 +1371,14 @@ vm_page_free_invalid(vm_page_t m)
 
 	KASSERT(vm_page_none_valid(m), ("page %p is valid", m));
 	KASSERT(!pmap_page_is_mapped(m), ("page %p is mapped", m));
-	vm_page_assert_xbusied(m);
 	KASSERT(m->object != NULL, ("page %p has no object", m));
 	VM_OBJECT_ASSERT_WLOCKED(m->object);
+
+	/*
+	 * We may be attempting to free the page as part of the handling for an
+	 * I/O error, in which case the page was xbusied by a different thread.
+	 */
+	vm_page_xbusy_claim(m);
 
 	/*
 	 * If someone has wired this page while the object lock