On 2018-05-07 21:16, Alex G. wrote:
On 05/07/2018 01:46 PM, okaya@xxxxxxxxxxxxxx wrote:
On 2018-05-07 19:36, Alex G. wrote:
Hi! Me again!
I'm seeing what appears to be a deadlock in the AER recovery path. It
seems that the device_lock() call in report_slot_reset() never
returns.
How we get there is interesting:
Can you give this patch a try?
Oh! Patches so soon? Yay!
https://patchwork.kernel.org/patch/10351515/
Thank you! I tried a few runs. there was one run where we didn't lock
up, but the other runs all went like before.
For comparison, the run that didn't deadlock looked like [2].
Sounds like there are multiple problems. With this patch, you shouldn't
see link down and up interrupts during reset but i do see them in the
log.
Can you also share a fail case log with this patch and a diff of your
hacks so that we know where prints are coming from.
Alex
[2] http://gtech.myftp.org/~mrnuke/nvme_logs/log-20180507-1429.log
Injection of the error happens by changing the maximum payload size
to
128 bytes from 256. This is on the switch upstream port.
When there's IO to the drive, switch sees a malformed TLP. Switch
reports error, AER handles it.
More IO goes, another error is triggered, and this time the root port
reports it. AER recovery hits the NVMe drive behind the affetced
upstream port and deadlocks.
I've added some printks in the AER handler to see which lock dies,
and I
have a fairly succinct log[1], also pasted below. It appears somebody
is
already holding the lock to the PCI device behind the sick upstream
port, and never releases it.
I'm not sure how to track down other users of the lock, and I"m
hoping
somebody may have a brighter idea.
Alex
[1] http://gtech.myftp.org/~mrnuke/nvme_logs/log-20180507-1308.log
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