unkillable process consuming 100% cpu

[Steve Kargl]

On Thu, Nov 07, 2019 at 03:32:23PM -0500, Mark Johnston wrote:
> On Thu, Nov 07, 2019 at 12:29:19PM -0800, Steve Kargl wrote:
> > I haven't seen anyone post about an unkillable process
> > (even by root), which consumes 100% cpu.
> > 
> > last pid:  4592;  load averages:  1.24,  1.08,  0.74   up 13+20:21:20  12:26:29
> > 68 processes:  2 running, 66 sleeping
> > CPU:  0.1% user,  0.0% nice, 12.6% system,  0.0% interrupt, 87.2% idle
> > Mem: 428M Active, 11G Inact, 138M Laundry, 2497M Wired, 1525M Buf, 2377M Free
> > Swap: 16G Total, 24M Used, 16G Free
> > 
> >   PID USERNAME    THR PRI NICE   SIZE    RES STATE    C   TIME    WCPU COMMAND
> > 69092 kargl         2  45    0   342M   148M CPU2     2  12:51 100.07% chrome
> > 
> > 
> > Neither of these have an effect.
> > 
> > kill -1 69092
> > kill -9 69069
> > 
> > Attempts to attach gdb831 to -p 69092 leads to hung xterm.
> 
> Could you please show us the output of "procstat -kk 69092"?

Just had another lock-up.  A force 'shutdown -r now' from a
remote terminal led to a console message about an unkillable
process.

Here's 'procstat -kk' for the stuck process with the long line wrapped.

  PID    TID COMM   TDNAME  KSTACK                       
  877 100161 Xorg   -       radeon_gem_busy_ioctl+0x30
                            drm_ioctl_kernel+0xf1
                            drm_ioctl+0x279
                            linux_file_ioctl+0x298
                            kern_ioctl+0x284
                            sys_ioctl+0x157
                            amd64_syscall+0x273
                            fast_syscall_common+0x101 
  877 100344 Xorg   X:rcs0  mi_switch+0xcb
                            sleepq_catch_signals+0x35d
                            sleepq_wait_sig+0xc
                            _sleep+0x1bd
                            umtxq_sleep+0x132
                            do_wait+0x3d6
                            __umtx_op_wait_uint_private+0x7e
                            amd64_syscall+0x273
                            fast_syscall_common+0x101 


It looks like radeonkms+drm is getting stuck.

-- 
Steve