Hello On 1/21/19 11:22 PM, Marc Gonzalez wrote: > Well, now we know for sure that the clk_scaling_lock is a red herring. > I applied the patch below, and still the system locked up: > > # dd if=/dev/sde of=/dev/null bs=1M status=progress > 3892314112 bytes (3.9 GB, 3.6 GiB) copied, 50.0042 s, 77.8 MB/s > > I can't seem to get the RCU stall warning anymore. How can I get > to the bottom of this issue? > Can you detail the system 'locked up' ? dd hangs there ? any hung task warning log ? hang forever or just hang for a relatively long time. And what is the status of the dd when it hangs ? Can you take some samples of the /proc/<dd's pid>/status and /proc/<dd's pid>/stack during the hang ? And also would you please share the dmesg log and config ? Since always fails with buffered read with fixed bytes, what is the capacity of your system memory ? Thanks Jianchao