On Thu, Oct 24, 2024 at 10:35:29AM +0100, John Garry wrote: > On 23/10/2024 21:39, Jan Kara wrote: > > On Wed 23-10-24 11:19:24, John Garry wrote: > > > Hi All, > > > > > > I have been seeing lockups reliably occur on v6.12-rc1, 3, 4 and linus' > > > master branch: > > > > > > Message from syslogd@jgarry-atomic-write-exp-e4-8-instance-20231214-1221 at > > > Oct 22 09:07:15 ... > > > kernel:watchdog: BUG: soft lockup - CPU#12 stuck for 26s! [khugepaged:154] > > > > BTW, can you please share logs which would contain full stacktraces that > > this softlockup reports produce? The attached dmesg is just from fresh > > boot... Thanks! > > > > thanks for getting back to me. > > So I think that enabling /proc/sys/kernel/softlockup_all_cpu_backtrace is > required there. Unfortunately my VM often just locks up without any sign of > life. Attach a "serial" console to the vm - add "console=ttyS0,115600" to the kernel command line and add "-serial pty" to the qemu command line. You can then attach something like minicom to the /dev/pts/X device that qemu creates for the console output and capture everything from initial boot right through to the softlockup traces that are emitted... -Dave. -- Dave Chinner david@xxxxxxxxxxxxx
