Messages in this thread Patch in this message | | | Date | Tue, 29 Jun 2021 10:25:42 +0200 | From | Daniel Wagner <> | Subject | Re: [PATCH 1/1] block: System crashes when cpu hotplug + bouncing port |
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On Tue, Jun 29, 2021 at 11:47:55AM +0800, Ming Lei wrote: > > >>data.ctx = __blk_mq_get_ctx(q, cpu); > > cpu=2048 if hctx_idx = 4 > > Yeah, that is the issue I mentioned, any CPU in hctx->cpumask becomes > offline, please try the following patch and see if it makes a > difference:
Given that cpumask_first_and() will return nr_cpu_ids in this case, can't we just bail out here and have to caller handle the error? I am able to reproduce the crash you reported in [1] and the fix [2] here works for me:
--- a/block/blk-mq.c +++ b/block/blk-mq.c @@ -469,6 +469,8 @@ struct request *blk_mq_alloc_request_hctx(struct request_queue *q, if (!blk_mq_hw_queue_mapped(data.hctx)) goto out_queue_exit; cpu = cpumask_first_and(data.hctx->cpumask, cpu_online_mask); + if (cpu >= nr_cpu_ids) + goto out_queue_exit; data.ctx = __blk_mq_get_ctx(q, cpu); if (!q->elevator) [1] https://lore.kernel.org/linux-block/20191117041233.GA30615@ming.t460p/ [2] https://lore.kernel.org/linux-block/20210608183339.70609-1-dwagner@suse.de/
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