linux-kernel - Re: [PATCH] kyber: Fix crash in kyber_finish

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Message-ID: <8b714da7-97b2-f8d2-4be7-c192130c33af@kernel.dk>
Date:   Mon, 7 Sep 2020 10:41:16 -0600
From:   Jens Axboe <axboe@...nel.dk>
To:     Yang Yang <yang.yang@...o.com>, linux-block@...r.kernel.org,
        linux-kernel@...r.kernel.org
Cc:     onlyfever@...oud.com, Omar Sandoval <osandov@...ndov.com>
Subject: Re: [PATCH] kyber: Fix crash in kyber_finish_request()

CC Omar

On 9/7/20 1:43 AM, Yang Yang wrote:
> Kernel crash when requeue flush request.
> It can be reproduced as below:
> 
> [    2.517297] Unable to handle kernel paging request at virtual address ffffffd8071c0b00
> ...
> [    2.517468] pc : clear_bit+0x18/0x2c
> [    2.517502] lr : sbitmap_queue_clear+0x40/0x228
> [    2.517503] sp : ffffff800832bc60 pstate : 00c00145
> ...
> [    2.517599] Process ksoftirqd/5 (pid: 51, stack limit = 0xffffff8008328000)
> [    2.517602] Call trace:
> [    2.517606]  clear_bit+0x18/0x2c
> [    2.517619]  kyber_finish_request+0x74/0x80
> [    2.517627]  blk_mq_requeue_request+0x3c/0xc0
> [    2.517637]  __scsi_queue_insert+0x11c/0x148
> [    2.517640]  scsi_softirq_done+0x114/0x130
> [    2.517643]  blk_done_softirq+0x7c/0xb0
> [    2.517651]  __do_softirq+0x208/0x3bc
> [    2.517657]  run_ksoftirqd+0x34/0x60
> [    2.517663]  smpboot_thread_fn+0x1c4/0x2c0
> [    2.517667]  kthread+0x110/0x120
> [    2.517669]  ret_from_fork+0x10/0x18
> 
> Signed-off-by: Yang Yang <yang.yang@...o.com>
> ---
>  block/kyber-iosched.c | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/block/kyber-iosched.c b/block/kyber-iosched.c
> index a38c5ab103d1..af73afe7a05c 100644
> --- a/block/kyber-iosched.c
> +++ b/block/kyber-iosched.c
> @@ -611,6 +611,9 @@ static void kyber_finish_request(struct request *rq)
>  {
>  	struct kyber_queue_data *kqd = rq->q->elevator->elevator_data;
>  
> +	if (unlikely(!(rq->rq_flags & RQF_ELVPRIV)))
> +		return;
> +
>  	rq_clear_domain_token(kqd, rq);
>  }
>  
> 


-- 
Jens Axboe