[34-longterm 099/196] slub: fix panic with DISCONTIGMEM

[Paul Gortmaker]

From: James Bottomley <James.Bottomley@xxxxxxxxxxxxxxxxxxxxx>

                   -------------------
    This is a commit scheduled for the next v2.6.34 longterm release.
    If you see a problem with using this for longterm, please comment.
                   -------------------

commit 4a5fa3590f09999f6db41bc386bce40848fa9f63 upstream.

Slub makes assumptions about page_to_nid() which are violated by
DISCONTIGMEM and !NUMA.  This violation results in a panic because
page_to_nid() can be non-zero for pages in the discontiguous ranges and
this leads to a null return by get_node().  The assertion by the
maintainer is that DISCONTIGMEM should only be allowed when NUMA is also
defined.  However, at least six architectures: alpha, ia64, m32r, m68k,
mips, parisc violate this.  The panic is a regression against slab, so
just mark slub broken in the problem configuration to prevent users
reporting these panics.

Acked-by: David Rientjes <rientjes@xxxxxxxxxx>
Acked-by: Pekka Enberg <penberg@xxxxxxxxxx>
Signed-off-by: James Bottomley <James.Bottomley@xxxxxxx>
Signed-off-by: Paul Gortmaker <paul.gortmaker@xxxxxxxxxxxxx>
---
 init/Kconfig |    1 +
 1 file changed, 1 insertion(+)

diff --git a/init/Kconfig b/init/Kconfig
index 5fe94b8..04e486cf 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -1052,6 +1052,7 @@ config SLAB
 	  per cpu and per node queues.
 
 config SLUB
+	depends on BROKEN || NUMA || !DISCONTIGMEM
 	bool "SLUB (Unqueued Allocator)"
 	help
 	   SLUB is a slab allocator that minimizes cache line usage
-- 
1.7.9.3

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