svn commit: r353964 - head/sys/vm

[Mark Johnston]

Author: markj
Date: Wed Oct 23 20:39:21 2019
New Revision: 353964
URL: https://svnweb.freebsd.org/changeset/base/353964

Log:
  Modify release_page() to handle a missing fault page.
  
  r353890 introduced a case where we may call release_page() with
  fs.m == NULL, since the fault handler may now lock the vnode prior
  to allocating a page for a page-in.
  
  Reported by:	jhb
  Reviewed by:	kib
  MFC with:	r353890
  Sponsored by:	The FreeBSD Foundation
  Differential Revision:	https://reviews.freebsd.org/D22120

Modified:
  head/sys/vm/vm_fault.c

Modified: head/sys/vm/vm_fault.c
==============================================================================
--- head/sys/vm/vm_fault.c	Wed Oct 23 20:37:15 2019	(r353963)
+++ head/sys/vm/vm_fault.c	Wed Oct 23 20:39:21 2019	(r353964)
@@ -154,11 +154,13 @@ static inline void
 release_page(struct faultstate *fs)
 {
 
-	vm_page_xunbusy(fs->m);
-	vm_page_lock(fs->m);
-	vm_page_deactivate(fs->m);
-	vm_page_unlock(fs->m);
-	fs->m = NULL;
+	if (fs->m != NULL) {
+		vm_page_xunbusy(fs->m);
+		vm_page_lock(fs->m);
+		vm_page_deactivate(fs->m);
+		vm_page_unlock(fs->m);
+		fs->m = NULL;
+	}
 }
 
 static inline void