[PATCH 3.16.y-ckt 047/216] blk-mq: use 'nr_cpu_ids' as highest CPU ID count for hwq <-> cpu map

Luis Henriques
2015-01-12T18:06:01Z

From: Jens Axboe <axboe@fb.com>

commit a33c1ba2913802b6fb23e974bb2f6a4e73c8b7ce upstream.

We currently use num_possible_cpus(), but that breaks on sparc64 where
the CPU ID space is discontig. Use nr_cpu_ids as the highest CPU ID
instead, so we don't end up reading from invalid memory.

Signed-off-by: Jens Axboe <axboe@fb.com>
Signed-off-by: Luis Henriques <luis.henriques@canonical.com>
---
block/blk-mq-cpumap.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/block/blk-mq-cpumap.c b/block/blk-mq-cpumap.c
index 1065d7c65fa1..72e5ed691e37 100644
--- a/block/blk-mq-cpumap.c
+++ b/block/blk-mq-cpumap.c
@@ -90,7 +90,7 @@ unsigned int *blk_mq_make_queue_map(struct blk_mq_tag_set *set)
unsigned int *map;

/* If cpus are offline, map them to first hctx */
- map = kzalloc_node(sizeof(*map) * num_possible_cpus(), GFP_KERNEL,
+ map = kzalloc_node(sizeof(*map) * nr_cpu_ids, GFP_KERNEL,
set->numa_node);
if (!map)
return NULL;
--
2.1.4