svn commit: r343673 - head/sys/vm

[Alexander Motin]

Author: mav
Date: Sat Feb  2 04:11:59 2019
New Revision: 343673
URL: https://svnweb.freebsd.org/changeset/base/343673

Log:
  Fix integer math overflow in UMA hash_alloc().
  
  512GB of ZFS ABD ARC means abd_chunk zone of 128M 4KB items.  To manage
  them UMA tries to allocate 2GB hash table, which size does not fit into
  the int variable, causing later allocation failure, which makes ARC shrink
  back below the 512GB, not letting it to use more RAM.  With this change I
  easily reached >700GB ARC size on 768GB RAM machine.
  
  MFC after:	1 week
  Sponsored by:	iXsystems, Inc.

Modified:
  head/sys/vm/uma_core.c

Modified: head/sys/vm/uma_core.c
==============================================================================
--- head/sys/vm/uma_core.c	Fri Feb  1 23:16:59 2019	(r343672)
+++ head/sys/vm/uma_core.c	Sat Feb  2 04:11:59 2019	(r343673)
@@ -623,7 +623,7 @@ static int
 hash_alloc(struct uma_hash *hash)
 {
 	int oldsize;
-	int alloc;
+	size_t alloc;
 
 	oldsize = hash->uh_hashsize;