* [patch] blk-mq: zero out ctx_map during initialization
@ 2013-10-21 17:57 Jeff Moyer
2013-10-21 19:12 ` Jens Axboe
0 siblings, 1 reply; 2+ messages in thread
From: Jeff Moyer @ 2013-10-21 17:57 UTC (permalink / raw)
To: jaxboe, linux-kernel
Hi,
ctx_map may contain random garbage, leading to (potentially chronic but
harmless) false positives in blk_mq_hctx_has_pending.
Note: I have not observed this in practice, just by code inspection.
Signed-off-by: Jeff Moyer <jmoyer@redhat.com>
diff --git a/block/blk-mq.c b/block/blk-mq.c
index 923e9e1..e9be5ed 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -1197,7 +1197,7 @@ static int blk_mq_init_hw_queues(struct request_queue *q,
break;
num_maps = ALIGN(nr_cpu_ids, BITS_PER_LONG) / BITS_PER_LONG;
- hctx->ctx_map = kmalloc_node(num_maps * sizeof(unsigned long),
+ hctx->ctx_map = kzalloc_node(num_maps * sizeof(unsigned long),
GFP_KERNEL, node);
if (!hctx->ctx_map)
break;
^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [patch] blk-mq: zero out ctx_map during initialization
2013-10-21 17:57 [patch] blk-mq: zero out ctx_map during initialization Jeff Moyer
@ 2013-10-21 19:12 ` Jens Axboe
0 siblings, 0 replies; 2+ messages in thread
From: Jens Axboe @ 2013-10-21 19:12 UTC (permalink / raw)
To: Jeff Moyer; +Cc: linux-kernel
On Mon, Oct 21 2013, Jeff Moyer wrote:
> Hi,
>
> ctx_map may contain random garbage, leading to (potentially chronic but
> harmless) false positives in blk_mq_hctx_has_pending.
>
> Note: I have not observed this in practice, just by code inspection.
It's the prudent thing to do in any case. Applied.
--
Jens Axboe
^ permalink raw reply [flat|nested] 2+ messages in thread
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