Messages in this thread | | | Date | Tue, 12 Jul 2022 15:49:29 +0200 | Subject | Re: [PATCH 1/1] nvme-pci: fix hang during error recovery when the PCI device is isolated | From | Hannes Reinecke <> |
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On 7/12/22 14:44, Niklas Schnelle wrote: > On s390 and powerpc PCI devices are isolated when an error is detected > and driver->err_handler->error_detected is called with an inaccessible > PCI device and PCI channel state set to pci_channel_io_frozen > (see Step 1 in Documentation/PCI/pci-error-recovery.rst). > > In the case of NVMe devices nvme_error_detected() then calls > nvme_dev_disable(dev, false) and requests a reset. After a successful > reset the device is accessible again and nvme_slot_reset() resets the > controller and queues nvme_reset_work() which then recovers the > controller. > > Since commit b98235d3a471 ("nvme-pci: harden drive presence detect in > nvme_dev_disable()") however nvme_dev_disable() no longer freezes the > queues if pci_device_is_present() returns false. This is the case for an > isolated PCI device. In principle this makes sense as there are no > accessible hardware queues to run. The problem though is that for > a previously live reset controller with online queues nvme_reset_work() > calls nvme_wait_freeze() which, without the freeze having been > initiated, then hangs forever. Fix this by starting the freeze in > nvme_slot_reset() which is the earliest point where we know the device > should be accessible again. > > Fixes: b98235d3a471 ("nvme-pci: harden drive presence detect in nvme_dev_disable()") > Signed-off-by: Niklas Schnelle <schnelle@linux.ibm.com> > --- > drivers/nvme/host/pci.c | 1 + > 1 file changed, 1 insertion(+) > > diff --git a/drivers/nvme/host/pci.c b/drivers/nvme/host/pci.c > index 193b44755662..7c0c61b74c30 100644 > --- a/drivers/nvme/host/pci.c > +++ b/drivers/nvme/host/pci.c > @@ -3399,6 +3399,7 @@ static pci_ers_result_t nvme_slot_reset(struct pci_dev *pdev) > dev_info(dev->ctrl.device, "restart after slot reset\n"); > pci_restore_state(pdev); > nvme_reset_ctrl(&dev->ctrl); > + nvme_start_freeze(&dev->ctrl); > return PCI_ERS_RESULT_RECOVERED; > } > I am not sure if that's the right fix. From your description the hang occurs as nvme_reset_ctrl() is calling nvme_wait_freeze() without an corresponding nvme_start_freeze(). So why are you calling it _after_ the call to nvme_reset_ctrl()?
Cheers,
Hannes
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