svn commit: r270387 - head/sys/vm

[Alan Cox]

Author: alc
Date: Sat Aug 23 05:24:31 2014
New Revision: 270387
URL: http://svnweb.freebsd.org/changeset/base/270387

Log:
  Relax one of the conditions for mapping a page on the fast path.
  
  Reviewed by:	kib
  X-MFC with:	r270011
  Sponsored by:	EMC / Isilon Storage Division

Modified:
  head/sys/vm/vm_fault.c

Modified: head/sys/vm/vm_fault.c
==============================================================================
--- head/sys/vm/vm_fault.c	Sat Aug 23 02:24:47 2014	(r270386)
+++ head/sys/vm/vm_fault.c	Sat Aug 23 05:24:31 2014	(r270387)
@@ -306,8 +306,9 @@ RetryFault:;
 		    (fs.first_object->flags & OBJ_MIGHTBEDIRTY) == 0)
 			goto fast_failed;
 		m = vm_page_lookup(fs.first_object, fs.first_pindex);
-		if (m == NULL || vm_page_busied(m) ||
-		    m->valid != VM_PAGE_BITS_ALL)
+		/* A busy page can be mapped for read|execute access. */
+		if (m == NULL || ((prot & VM_PROT_WRITE) != 0 &&
+		    vm_page_busied(m)) || m->valid != VM_PAGE_BITS_ALL)
 			goto fast_failed;
 		result = pmap_enter(fs.map->pmap, vaddr, m, prot,
 		   fault_type | PMAP_ENTER_NOSLEEP | (wired ? PMAP_ENTER_WIRED :