[PATCH] nvme: fix PCIe subsystem reset controller state transition

John Meneghini jmeneghi at redhat.com
Thu Jan 15 11:32:21 PST 2026 

Tested-by: John Menehgini <jmeneghi at redhat.com>

I've tested this patch with 6.19.0-rc5+ on both x86_64 and ppc64le platforms.

Note that, on the PowerPC platform the following additional patch was needed:

https://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux.git/commit/?h=next&id=815a8d2feb5615ae7f0b5befd206af0b0160614c

/John

[root at rdma-cert-03-lp10 ~]# uname -a
Linux rdma-cert-03-lp10.rdma.lab.eng.rdu2.redhat.com 6.19.0-rc5+ #1 SMP Thu Jan 15 14:14:45 EST 2026 ppc64le GNU/Linux
[root at rdma-cert-03-lp10 ~]# dmesg -C
[root at rdma-cert-03-lp10 ~]# dmesg -Tw&
[1] 15696
[root at rdma-cert-03-lp10 ~]# nvme list-subsys
nvme-subsys0 - NQN=nqn.1994-11.com.samsung:nvme:PM1735:HHHL:S4WANA0R400032
                hostnqn=nqn.2014-08.org.nvmexpress:uuid:1654a627-93b6-4650-ba90-f4dc7a2fd3ee
                iopolicy=numa
\
  +- nvme0 pcie 0018:01:00.0 live
[root at rdma-cert-03-lp10 ~]# [Thu Jan 15 14:24:11 2026] block nvme0n1: No UUID available providing old NGUID

[root at rdma-cert-03-lp10 ~]# nvme subsystem-reset /dev/nvme0
[root at rdma-cert-03-lp10 ~]# nvme list-subsys /dev/nvme0n1
[Thu Jan 15 14:25:29 2026] EEH: Recovering PHB#18-PE#10000
[Thu Jan 15 14:25:29 2026] EEH: PE location: N/A, PHB location: N/A
[Thu Jan 15 14:25:29 2026] EEH: Frozen PHB#18-PE#10000 detected
[Thu Jan 15 14:25:29 2026] EEH: Call Trace:
[Thu Jan 15 14:25:29 2026] EEH: [00000000d71b2d94] __eeh_send_failure_event+0x78/0x160
[Thu Jan 15 14:25:29 2026] EEH: [00000000465f9a5f] eeh_dev_check_failure+0x2c0/0x700
[Thu Jan 15 14:25:29 2026] EEH: [0000000015f9541b] nvme_timeout+0x274/0x690 [nvme]
[Thu Jan 15 14:25:29 2026] EEH: [00000000231862b5] blk_mq_handle_expired+0xb0/0x130
[Thu Jan 15 14:25:29 2026] EEH: [0000000080ea6b3b] bt_iter+0xf8/0x140
[Thu Jan 15 14:25:29 2026] EEH: [00000000b79a498f] blk_mq_queue_tag_busy_iter+0x35c/0x700
[Thu Jan 15 14:25:29 2026] EEH: [0000000077a6dbdc] blk_mq_timeout_work+0x1a8/0x240
[Thu Jan 15 14:25:29 2026] EEH: [000000000ef3edde] process_one_work+0x1f4/0x500
[Thu Jan 15 14:25:29 2026] EEH: [0000000039a4e1cd] worker_thread+0x33c/0x510
[Thu Jan 15 14:25:29 2026] EEH: [000000005a866bd1] kthread+0x154/0x170
[Thu Jan 15 14:25:29 2026] EEH: [0000000077e75258] start_kernel_thread+0x14/0x18
[Thu Jan 15 14:25:29 2026] EEH: This PCI device has failed 1 times in the last hour and will be permanently disabled after 5 failures.
[Thu Jan 15 14:25:29 2026] EEH: Notify device drivers to shutdown
[Thu Jan 15 14:25:29 2026] EEH: Beginning: 'error_detected(IO frozen)'
[Thu Jan 15 14:25:29 2026] PCI 0018:01:00.0#10000: EEH: Invoking nvme->error_detected(IO frozen)
[Thu Jan 15 14:25:29 2026] nvme nvme0: frozen state error detected, reset controller
[Thu Jan 15 14:25:29 2026] block nvme0n1: no usable path - requeuing I/O
[Thu Jan 15 14:25:29 2026] block nvme0n1: no usable path - requeuing I/O
[Thu Jan 15 14:25:29 2026] block nvme0n1: no usable path - requeuing I/O
[Thu Jan 15 14:25:29 2026] block nvme0n1: no usable path - requeuing I/O
[Thu Jan 15 14:25:29 2026] nvme nvme0: Identify namespace failed (-4)
[Thu Jan 15 14:25:29 2026] PCI 0018:01:00.0#10000: EEH: nvme driver reports: 'need reset'
[Thu Jan 15 14:25:29 2026] EEH: Finished:'error_detected(IO frozen)' with aggregate recovery state:'need reset'
[Thu Jan 15 14:25:29 2026] EEH: Collect temporary log
[Thu Jan 15 14:25:29 2026] EEH: of node=0018:01:00.0
[Thu Jan 15 14:25:29 2026] EEH: PCI device/vendor: a824144d
[Thu Jan 15 14:25:29 2026] EEH: PCI cmd/status register: 00100140
[Thu Jan 15 14:25:29 2026] EEH: PCI-E capabilities and status follow:
[Thu Jan 15 14:25:29 2026] EEH: PCI-E 00: 0002b010 10008fe2 00002910 00437084
[Thu Jan 15 14:25:29 2026] EEH: PCI-E 10: 10840000 00000000 00000000 00000000
[Thu Jan 15 14:25:29 2026] EEH: PCI-E 20: 00000000
[Thu Jan 15 14:25:29 2026] EEH: PCI-E AER capability register set follows:
[Thu Jan 15 14:25:29 2026] EEH: PCI-E AER 00: 14820001 00000000 00400000 00462030
[Thu Jan 15 14:25:29 2026] EEH: PCI-E AER 10: 00000000 0000e000 000002a0 00000000
[Thu Jan 15 14:25:29 2026] EEH: PCI-E AER 20: 00000000 00000000 00000000 00000000
[Thu Jan 15 14:25:29 2026] EEH: PCI-E AER 30: 00000000 00000000
[Thu Jan 15 14:25:29 2026] RTAS: event: 3, Type: Platform Error (224), Severity: 2
[Thu Jan 15 14:25:29 2026] EEH: Reset without hotplug activity
[Thu Jan 15 14:25:29 2026] block nvme0n1: no usable path - requeuing I/O
[Thu Jan 15 14:25:29 2026] block nvme0n1: no usable path - requeuing I/O
[Thu Jan 15 14:25:31 2026] EEH: Beginning: 'slot_reset'
[Thu Jan 15 14:25:31 2026] PCI 0018:01:00.0#10000: EEH: Invoking nvme->slot_reset()
[Thu Jan 15 14:25:31 2026] nvme nvme0: restart after slot reset
[Thu Jan 15 14:25:31 2026] PCI 0018:01:00.0#10000: EEH: nvme driver reports: 'recovered'
[Thu Jan 15 14:25:31 2026] EEH: Finished:'slot_reset' with aggregate recovery state:'recovered'
[Thu Jan 15 14:25:31 2026] EEH: Notify device driver to resume
[Thu Jan 15 14:25:31 2026] EEH: Beginning: 'resume'
[Thu Jan 15 14:25:31 2026] PCI 0018:01:00.0#10000: EEH: Invoking nvme->resume()
[Thu Jan 15 14:25:31 2026] nvme nvme0: D3 entry latency set to 10 seconds
[Thu Jan 15 14:25:31 2026] nvme nvme0: 16/0/0 default/read/poll queues
[Thu Jan 15 14:25:31 2026] PCI 0018:01:00.0#10000: EEH: nvme driver reports: 'none'
[Thu Jan 15 14:25:31 2026] EEH: Finished:'resume'
[Thu Jan 15 14:25:31 2026] EEH: Recovery successful.

[root at rdma-cert-03-lp10 ~]# nvme list-subsys /dev/nvme0n1
nvme-subsys0 - NQN=nqn.1994-11.com.samsung:nvme:PM1735:HHHL:S4WANA0R400032
                hostnqn=nqn.2014-08.org.nvmexpress:uuid:1654a627-93b6-4650-ba90-f4dc7a2fd3ee
                iopolicy=numa
\
  +- nvme0 pcie 0018:01:00.0 live optimized

On 1/14/26 2:24 AM, Nilay Shroff wrote:
> The commit d2fe192348f9 (“nvme: only allow entering LIVE from CONNECTING
> state”) disallows controller state transitions directly from RESETTING
> to LIVE. However, the NVMe PCIe subsystem reset path relies on this
> transition to recover the controller on PowerPC (PPC) systems.
> 
> On PPC systems, issuing a subsystem reset causes a temporary loss of
> communication with the NVMe adapter. A subsequent PCIe MMIO read then
> triggers EEH recovery, which restores the PCIe link and brings the
> controller back online. For EEH recovery to proceed correctly, the
> controller must transition back to the LIVE state.
> 
> Due to the changes introduced by commit d2fe192348f9 (“nvme: only allow
> entering LIVE from CONNECTING state”), the controller can no longer
> transition directly from RESETTING to LIVE. As a result, EEH recovery
> exits prematurely, leaving the controller stuck in the RESETTING state.
> 
> Fix this by explicitly transitioning the controller state from RESETTING
> to CONNECTING and then to LIVE. This satisfies the updated state
> transition rules and allows the controller to be successfully recovered
> on PPC systems following a PCIe subsystem reset.
> 
> Cc: stable at vger.kernel.org
> Fixes: d2fe192348f9 ("nvme: only allow entering LIVE from CONNECTING state")
> Signed-off-by: Nilay Shroff <nilay at linux.ibm.com>
> ---
>   drivers/nvme/host/pci.c | 5 ++++-
>   1 file changed, 4 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/nvme/host/pci.c b/drivers/nvme/host/pci.c
> index 0e4caeab739c..3027bba232de 100644
> --- a/drivers/nvme/host/pci.c
> +++ b/drivers/nvme/host/pci.c
> @@ -1532,7 +1532,10 @@ static int nvme_pci_subsystem_reset(struct nvme_ctrl *ctrl)
>   	}
>   
>   	writel(NVME_SUBSYS_RESET, dev->bar + NVME_REG_NSSR);
> -	nvme_change_ctrl_state(ctrl, NVME_CTRL_LIVE);
> +
> +	if (!nvme_change_ctrl_state(ctrl, NVME_CTRL_CONNECTING) ||
> +	    !nvme_change_ctrl_state(ctrl, NVME_CTRL_LIVE))
> +		goto unlock;
>   
>   	/*
>   	 * Read controller status to flush the previous write and trigger a

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