From: Yu Kuai <yukuai1@huaweicloud.com>
To: Yu Kuai <yukuai1@huaweicloud.com>,
Guangwu Zhang <guazhang@redhat.com>,
linux-block@vger.kernel.org, io-uring@vger.kernel.org,
Jeff Moyer <jmoyer@redhat.com>, Ming Lei <ming.lei@redhat.com>,
"yukuai (C)" <yukuai3@huawei.com>
Subject: Re: [bug report] BUG: kernel NULL pointer dereference, address: 0000000000000048
Date: Wed, 10 May 2023 10:00:14 +0800 [thread overview]
Message-ID: <007af59f-4f4c-f779-a1b6-aaa81ff640b3@huaweicloud.com> (raw)
In-Reply-To: <cde5d326-4dcb-5b9c-9d58-fb1ef4b7f7a8@huaweicloud.com>
Hi,
在 2023/05/10 9:49, Yu Kuai 写道:
> Hi,
>
> 在 2023/05/10 9:29, Yu Kuai 写道:
>> Hi,
>>
>> 在 2023/05/10 8:49, Guangwu Zhang 写道:
>>> Hi,
>>>
>>> We found this kernel NULL pointer issue with latest
>>> linux-block/for-next, please check it.
>>>
>>> Kernel repo:
>>> https://git.kernel.org/pub/scm/linux/kernel/git/axboe/linux-block.git
>>>
>>>
>>> [ 112.483804] BUG: kernel NULL pointer dereference, address:
>>> 0000000000000048
>
> Base on this offset, 0x48 match bio->bi_blkg, so I guess this is because
> bio is NULL, so the problem is that passthrough request insert into
> elevator.
>
Sorry that attached patch has some problem, please try this one.
diff --git a/block/blk-mq.c b/block/blk-mq.c
index f6dad0886a2f..bd94d8a5416f 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -2712,6 +2712,7 @@ static void blk_mq_dispatch_plug_list(struct
blk_plug *plug, bool from_sched)
struct request **requeue_lastp = &requeue_list;
unsigned int depth = 0;
LIST_HEAD(list);
+ LIST_HEAD(passthrough_list);
do {
struct request *rq = rq_list_pop(&plug->mq_list);
@@ -2723,7 +2724,10 @@ static void blk_mq_dispatch_plug_list(struct
blk_plug *plug, bool from_sched)
rq_list_add_tail(&requeue_lastp, rq);
continue;
}
- list_add(&rq->queuelist, &list);
+ if (blk_rq_is_passthrough(rq))
+ list_add(&rq->queuelist, &passthrough_list);
+ else
+ list_add(&rq->queuelist, &list);
depth++;
} while (!rq_list_empty(plug->mq_list));
@@ -2731,6 +2735,9 @@ static void blk_mq_dispatch_plug_list(struct
blk_plug *plug, bool from_sched)
trace_block_unplug(this_hctx->queue, depth, !from_sched);
percpu_ref_get(&this_hctx->queue->q_usage_counter);
+ if (!list_empty(&passthrough_list))
+ blk_mq_insert_requests(this_hctx, this_ctx,
&passthrough_list,
+ from_sched);
if (this_hctx->queue->elevator) {
this_hctx->queue->elevator->type->ops.insert_requests(this_hctx,
&list, 0);
Thanks,
Kuai
next prev parent reply other threads:[~2023-05-10 2:00 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-05-10 0:49 [bug report] BUG: kernel NULL pointer dereference, address: 0000000000000048 Guangwu Zhang
2023-05-10 1:29 ` Yu Kuai
2023-05-10 1:49 ` Yu Kuai
2023-05-10 2:00 ` Yu Kuai [this message]
2023-05-10 2:17 ` Jens Axboe
2023-05-10 3:20 ` Yu Kuai
[not found] ` <CAGS2=YocNy9PkgRzzRdHAK1gGdjMxzA--PYS=sPrX_nCe4U6QA@mail.gmail.com>
2023-05-10 6:39 ` Ming Lei
2023-05-10 6:55 ` Yu Kuai
2023-05-10 12:08 ` Guangwu Zhang
2023-05-10 4:52 ` Guangwu Zhang
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