[Bug Report] PCIe errinject and hot-unplug causes nvme driver hang

[Sagi Grimberg]

On 18/04/2024 15:52, Nilay Shroff wrote:
> Hi,
>
> We found nvme driver hangs when disk IO is ongoing and if we inject pcie error and hot-unplug (not physical but logical unplug) the nvme disk.
>
> Notes and observations:
> ======================
> This is observed on the latest linus kernel tree (v6.9-rc4) however we believe this issue shall also be present on the older kernels.
>
> Test details:
> =============
> Steps to reproduce this issue:
>
> 1. Run some disk IO using fio or any other tool
> 2. While disk IO is running, inject pci error
> 3. disable the slot where nvme disk is attached (echo 0 > /sys/bus/pci/slots/<slot-no>/power)
>
> Kernel Logs:
> ============
> When we follow steps described in the test details we get the below logs:
>
> [  295.240811] nvme nvme1: controller is down; will reset: CSTS=0xffffffff, PCI_STATUS=0x10
> [  295.240837] nvme nvme1: Does your device have a faulty power saving mode enabled?
> [  295.240845] nvme nvme1: Try "nvme_core.default_ps_max_latency_us=0 pcie_aspm=off" and report a bug
> [  490.381591] INFO: task bash:2510 blocked for more than 122 seconds.
> [  490.381614]       Not tainted 6.9.0-rc4+ #8
> [  490.381618] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
> [  490.381623] task:bash            state:D stack:0     pid:2510  tgid:2510  ppid:2509   flags:0x00042080
> [  490.381632] Call Trace:
> [  490.381635] [c00000006748f510] [c00000006748f550] 0xc00000006748f550 (unreliable)
> [  490.381644] [c00000006748f6c0] [c00000000001f3fc] __switch_to+0x13c/0x220
> [  490.381654] [c00000006748f720] [c000000000fb87e0] __schedule+0x268/0x7c4
> [  490.381663] [c00000006748f7f0] [c000000000fb8d7c] schedule+0x40/0x108
> [  490.381669] [c00000006748f860] [c000000000808bb4] blk_mq_freeze_queue_wait+0xa4/0xec
> [  490.381676] [c00000006748f8c0] [c00000000081eba8] del_gendisk+0x284/0x464
> [  490.381683] [c00000006748f920] [c0080000064c74a4] nvme_ns_remove+0x138/0x2ac [nvme_core]
> [  490.381697] [c00000006748f960] [c0080000064c7704] nvme_remove_namespaces+0xec/0x198 [nvme_core]
> [  490.381710] [c00000006748f9d0] [c008000006704b70] nvme_remove+0x80/0x168 [nvme]
> [  490.381752] [c00000006748fa10] [c00000000092a10c] pci_device_remove+0x6c/0x110
> [  490.381776] [c00000006748fa50] [c000000000a4f504] device_remove+0x70/0xc4
> [  490.381786] [c00000006748fa80] [c000000000a515d8] device_release_driver_internal+0x2a4/0x324
> [  490.381801] [c00000006748fad0] [c00000000091b528] pci_stop_bus_device+0xb8/0x104
> [  490.381817] [c00000006748fb10] [c00000000091b910] pci_stop_and_remove_bus_device+0x28/0x40
> [  490.381826] [c00000006748fb40] [c000000000072620] pci_hp_remove_devices+0x90/0x128
> [  490.381831] [c00000006748fbd0] [c008000004440504] disable_slot+0x40/0x90 [rpaphp]
> [  490.381839] [c00000006748fc00] [c000000000956090] power_write_file+0xf8/0x19c
> [  490.381846] [c00000006748fc80] [c00000000094b4f8] pci_slot_attr_store+0x40/0x5c
> [  490.381851] [c00000006748fca0] [c0000000006e5dc4] sysfs_kf_write+0x64/0x78
> [  490.381858] [c00000006748fcc0] [c0000000006e48d8] kernfs_fop_write_iter+0x1b0/0x290
> [  490.381864] [c00000006748fd10] [c0000000005e0f4c] vfs_write+0x3b0/0x4f8
> [  490.381871] [c00000006748fdc0] [c0000000005e13c0] ksys_write+0x84/0x140
> [  490.381876] [c00000006748fe10] [c000000000030a84] system_call_exception+0x124/0x330
> [  490.381882] [c00000006748fe50] [c00000000000cedc] system_call_vectored_common+0x15c/0x2ec
>
> NVMe controller state:
> ======================
> # cat /sys/class/nvme/nvme1/state
> deleting (no IO)
>
> Process State:
> ==============
> # ps -aex
>     [..]
>     2510 pts/2    Ds+    0:00 -bash USER=root LOGNAME=root HOME=/root PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin SHELL=/bin/bash TERM=xterm-256colo
>     2549 ?        Ds     0:14 fio --filename=/dev/nvme1n1 --direct=1 --rw=randrw --bs=4k --ioengine=psync --iodepth=256 --runtime=300 --numjobs=1 --time_based
>     [..]
>
> Observation:
> ============
> As it's apparent from the above logs that "disable-slot" (pid 2510) is waiting (uninterruptible-sleep)
> for queue to be freezed because the in-flight IO(s) couldn't finish. Moreover the IO(s) which were
> in-flight actually times-out however nvme_timeout() doesn't cancel those IOs but logs this error
> "Try "nvme_core.default_ps_max_latency_us=0 pcie_aspm=off" and report a bug" and returns BLK_EH_DONE.
> As those in-fligh IOs were not cancelled, the NVMe driver code which runs in the context of
> "disable-slot" couldn't forward progress and NVMe controller state remains in "deleting (no IO)"
> indefinitely. The only way we found to come out of this state is to reboot the system.
>
> Proposed fix:
> ============
> static void nvme_remove(struct pci_dev *pdev)
> {
> 	struct nvme_dev *dev = pci_get_drvdata(pdev);
>
> 	nvme_change_ctrl_state(&dev->ctrl, NVME_CTRL_DELETING);
> 	pci_set_drvdata(pdev, NULL);
>
> 	if (!pci_device_is_present(pdev)) {
> 		nvme_change_ctrl_state(&dev->ctrl, NVME_CTRL_DEAD);
> 		nvme_dev_disable(dev, true);
> 	}
> 	flush_work(&dev->ctrl.reset_work);
> 	nvme_stop_ctrl(&dev->ctrl);
> 	nvme_remove_namespaces(&dev->ctrl); <== here cntrl state is set to "deleting (no IO)"
>          [..]
> }
>
> As shown above, nvme_remove() invokes nvme_dev_disable(), however, it is only invoked if the
> device is physically removed. As nvme_dev_disable() helps cancel pending IOs, does it makes
> sense to unconditionally cancel pending IOs before moving on? Or are there any side effect if
> we were to unconditionally invoke nvme_dev_disable() at the first place?

Shouldn't the correct place to handle the cancellation is 
nvme_error_detected() given that the
pci error is preventing the request from completing and the timeout 
handler from addressing it?