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Ryzen linux kernel bug 196683 - Random Soft Lockup

Question asked by imshalla on Feb 17, 2018
Latest reply on Feb 27, 2020 by truedoom

I have Ryzen 7 1800X, ASUS Prime X370-PRO, running Fedora 26 and 27.


The damn thing has not worked properly since I bought it.


My first CPU was RMA'd, and the replacement does not appear to suffer from the SEGV fault.


However, both the original and the replacement CPU both crash regularly:


  * occasionally with streams of "watchdog: BUG: soft lockup" events being logged,


  * but mostly the system just stops and I can find no logging that tells me why.


At I find bug 196683, where a "workaround" is suggested:


1) kernel configured:  CONFIG_RCU_NOCB_CPU=y


2) kernel command-line:  rcu-nocbs=0-15


But with kernel 4.14.18-300.fc27 I find the machine has stopped over night (when it is idle), every two or three days.


I have added kernel command-line "processor.max_cstate=5", which may help with the crashes, but (I assume) not with the electricity bill :-(


Does anybody understand what the real fault is ?  A "workaround" is all very well, but not entirely satisfactory.  It's not as if this is a new device any more.