linux-kernel - Re: [PATCH] nvme-pci: Don't WARN_ON in nvme_reset

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Date:   Mon, 12 Jul 2021 21:24:00 +0800
From:   Zhihao Cheng <chengzhihao1@...wei.com>
To:     <kbusch@...nel.org>, <axboe@...com>, <hch@....de>,
        <sagi@...mberg.me>, <rakesh@...era.com>
CC:     <linux-nvme@...ts.infradead.org>, <linux-kernel@...r.kernel.org>,
        <yukuai3@...wei.com>
Subject: Re: [PATCH] nvme-pci: Don't WARN_ON in nvme_reset_work if ctrl.state
 is not RESETTING

在 2021/7/5 21:38, Zhihao Cheng 写道:
> Followling process:
> nvme_probe
>    nvme_reset_ctrl
>      nvme_change_ctrl_state(ctrl, NVME_CTRL_RESETTING)
>      queue_work(nvme_reset_wq, &ctrl->reset_work)
>
> -------------->	nvme_remove
> 		  nvme_change_ctrl_state(&dev->ctrl, NVME_CTRL_DELETING)
> worker_thread
>    process_one_work
>      nvme_reset_work
>      WARN_ON(dev->ctrl.state != NVME_CTRL_RESETTING)
>
> , which will trigger WARN_ON in nvme_reset_work():
> [  127.534298] WARNING: CPU: 0 PID: 139 at drivers/nvme/host/pci.c:2594
> [  127.536161] CPU: 0 PID: 139 Comm: kworker/u8:7 Not tainted 5.13.0
> [  127.552518] Call Trace:
> [  127.552840]  ? kvm_sched_clock_read+0x25/0x40
> [  127.553936]  ? native_send_call_func_single_ipi+0x1c/0x30
> [  127.555117]  ? send_call_function_single_ipi+0x9b/0x130
> [  127.556263]  ? __smp_call_single_queue+0x48/0x60
> [  127.557278]  ? ttwu_queue_wakelist+0xfa/0x1c0
> [  127.558231]  ? try_to_wake_up+0x265/0x9d0
> [  127.559120]  ? ext4_end_io_rsv_work+0x160/0x290
> [  127.560118]  process_one_work+0x28c/0x640
> [  127.561002]  worker_thread+0x39a/0x700
> [  127.561833]  ? rescuer_thread+0x580/0x580
> [  127.562714]  kthread+0x18c/0x1e0
> [  127.563444]  ? set_kthread_struct+0x70/0x70
> [  127.564347]  ret_from_fork+0x1f/0x30
>
> The preceding problem can be easily reproduced by executing following
> script (based on blktests suite):
> test() {
>    pdev="$(_get_pci_dev_from_blkdev)"
>    sysfs="/sys/bus/pci/devices/${pdev}"
>    for ((i = 0; i < 10; i++)); do
>      echo 1 > "$sysfs/remove"
>      echo 1 > /sys/bus/pci/rescan
>    done
> }
>
> Since the device ctrl could be updated as an non-RESETTING state by
> repeating probe/remove in userspace (which is a normal situation), we
> can replace stack dumping WARN_ON with a warnning message.
>
> Fixes: 82b057caefaff ("nvme-pci: fix multiple ctrl removal schedulin")
> Signed-off-by: Zhihao Cheng <chengzhihao1@...wei.com>
> ---
>   drivers/nvme/host/pci.c | 4 +++-
>   1 file changed, 3 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/nvme/host/pci.c b/drivers/nvme/host/pci.c
> index a29b170701fc..966a4c84e699 100644
> --- a/drivers/nvme/host/pci.c
> +++ b/drivers/nvme/host/pci.c
> @@ -2591,7 +2591,9 @@ static void nvme_reset_work(struct work_struct *work)
>   	bool was_suspend = !!(dev->ctrl.ctrl_config & NVME_CC_SHN_NORMAL);
>   	int result;
>   
> -	if (WARN_ON(dev->ctrl.state != NVME_CTRL_RESETTING)) {
> +	if (dev->ctrl.state != NVME_CTRL_RESETTING) {
> +		dev_warn(dev->ctrl.device, "ctrl state %d is not RESETTING\n",
> +			 dev->ctrl.state);
>   		result = -ENODEV;
>   		goto out;
>   	}

friendly ping