svn commit: r343724 - head/sys/kern

[Konstantin Belousov]

Author: kib
Date: Sun Feb  3 21:31:40 2019
New Revision: 343724
URL: https://svnweb.freebsd.org/changeset/base/343724

Log:
  Do not call PHOLD() while owning the allproc_lock sx.
  
  Otherwise the lock might recurse in faultin() if the process is
  swapped out.
  
  Reported by:	zeising
  Sponsored by:	The FreeBSD Foundation
  MFC after:	1 week

Modified:
  head/sys/kern/kern_proc.c

Modified: head/sys/kern/kern_proc.c
==============================================================================
--- head/sys/kern/kern_proc.c	Sun Feb  3 21:28:58 2019	(r343723)
+++ head/sys/kern/kern_proc.c	Sun Feb  3 21:31:40 2019	(r343724)
@@ -3112,8 +3112,8 @@ allproc_loop:
 			PROC_UNLOCK(p);
 			continue;
 		}
-		_PHOLD(p);
 		sx_xunlock(&allproc_lock);
+		_PHOLD(p);
 		r = thread_single(p, SINGLE_ALLPROC);
 		if (r != 0)
 			restart = true;