Re: [BUG] RCU hang with io_uring nvme polling

[Ben Carey]

On Sat, Jul 4, 2026 at 3:35 PM Ben Carey
<benjamin.james.carey3@xxxxxxxxx> wrote:
> We've seen, however, that the timeout can occur a large number of times even
> with high queue saturation. When running the fio job below we observed the
> timeout 132757 times, which I'm concerned could negatively impact bandwidth.
>
> fio --bs=128K --direct=1 --iodepth=256 --runtime=200 --rw=randread \
>     --time_based \
>   --ioengine=io_uring --hipri=1 --fixedbufs=0 --registerfiles=0 \
>     --sqthread_poll=0 \
>   --numjobs=32 --name=job0 --output-format=json --clocksource=clock_gettime \
>   --filename=/dev/nvme0n1

I should note this was while running in a VM issuing IO to a virtual NVMe
device.