On Wed, Jul 31, 2019 at 04:20:12PM +0000, Visa Hankala wrote: > On Wed, Jul 31, 2019 at 05:46:08PM +0200, Raimo Niskanen wrote: > > I have enabled Witness, it went so-so. We'll see what it catches. > > > > I downloaded 6.5 amd64 src.tar.gz and sys.tar.gz, unpacked them, > > applied all patches for stable 001-006 and built a kernel with: > > include "arch/amd64/conf/GENERIC" > > option MULTIPROCESSOR > > option MP_LOCKDEBUG > > option WITNESS > > > > Then I activated in /etc/sysctl.conf: > > ddb.console=1 > > kern.witness.locktrace=1 > > kern.witness.watch=3 > > > > For fun, I pressed Ctrl+Alt+Esc at the console, got a ddb> prompt and typed > > "show witness". It printed lots of info, I scrolled down to the end, but > > during the printout there was an UVM fault: > > > > Spin locks: > > /usr/src/sys/.... > > : > > bla bla bla > > : > > uvm_fault(0xffffffff81e03b50, 0xffff800022368360, 0, 1) -> e > > kernel: page fault trap, code=0 > > Faulted in DDB: continuing... > > The output of "show witness" is unlikely to be useful in your case. > It is more of a tool for debugging witness. You can ignore it. > However, "show all locks" might display interesting information > after a witness-related panic.
Ok, great! It is just that an uvm_fault during show witness felt like a bad thing... -- / Raimo Niskanen, Erlang/OTP, Ericsson AB
