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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Zhihao Cheng <chengzhihao1@huawei.com>,
        Sasha Levin <sashal@kernel.org>
Subject: [PATCH 4.19 084/120] nvme-pci: dont WARN_ON in nvme_reset_work if ctrl.state is not RESETTING
Date:   Mon, 26 Jul 2021 17:38:56 +0200
Message-Id: <20210726153835.077673166@linuxfoundation.org>
In-Reply-To: <20210726153832.339431936@linuxfoundation.org>
References: <20210726153832.339431936@linuxfoundation.org>
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From: Zhihao Cheng <chengzhihao1@huawei.com>

[ Upstream commit 7764656b108cd308c39e9a8554353b8f9ca232a3 ]

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@huawei.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 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 8f1f10fa0dd6..d7cf3202cdd3 100644
--- a/drivers/nvme/host/pci.c
+++ b/drivers/nvme/host/pci.c
@@ -2273,7 +2273,9 @@ static void nvme_reset_work(struct work_struct *work)
 	int result;
 	enum nvme_ctrl_state new_state = NVME_CTRL_LIVE;
 
-	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;
 	}
-- 
2.30.2