[PATCH] x86_64: Fix the node cpumask of a cpu going down

Currently, x86_64 and ia64 arches do not clear the corresponding bits
in the node's cpumask when a cpu goes down or cpu bring up is cancelled.
This is buggy since there are pieces of common code where the cpumask is
checked in the cpu down code path to decide on things (like in  the slab
down path).  PPC does the right thing, but x86_64 and ia64 don't (This
was the reason Sonny hit upon a slab bug during cpu offline on ppc and
could not reproduce on other arches).  This patch fixes it for x86_64.
I won't attempt ia64 as I cannot test it.

Credit for spotting this should go to Alok.

Signed-off-by: Alok N Kataria <alokk@calsoftinc.com>
Signed-off-by: Ravikiran Thirumalai <kiran@scalex86.org>
Signed-off-by: Shai Fultheim <shai@scalex86.org>
Signed-off-by: Andi Kleen <ak@suse.de>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 7 insertions, 0 deletions

diff --git a/include/asm-x86_64/numa.h b/include/asm-x86_64/numa.h
index 34e434ce3268..dffe276ca2df 100644
--- a/include/asm-x86_64/numa.h
+++ b/include/asm-x86_64/numa.h
@@ -22,8 +22,15 @@ extern void numa_set_node(int cpu, int node);
 extern unsigned char apicid_to_node[256];
 #ifdef CONFIG_NUMA
 extern void __init init_cpu_to_node(void);
+
+static inline void clear_node_cpumask(int cpu)
+{
+        clear_bit(cpu, &node_to_cpumask[cpu_to_node(cpu)]);
+}
+
 #else
 #define init_cpu_to_node() do {} while (0)
+#define clear_node_cpumask(cpu) do {} while (0)
 #endif
 
 #define NUMA_NO_NODE 0xff