Thomas Gleixner <t...@linutronix.de> writes: > On Tue, 3 Oct 2017, Thomas Gleixner wrote: >> On Tue, 3 Oct 2017, Thomas Gleixner wrote: >> > On Tue, 3 Oct 2017, Michael Ellerman wrote: >> > > Hmm, I tried that patch, it makes the warning go away. But then I >> > > triggered a deliberate hard lockup and got nothing. >> > > >> > > Then I went back to the existing code (in linux-next), and I still get >> > > no warning from a deliberate hard lockup. >> > > >> > > So seems there may be some more gremlins. Will test more in the morning. >> > >> > Hrm. That's weird. I'll have a look and send a proper patch series on top >> > of next. >> >> The major difference is that the reworked code utilizes >> watchdog_nmi_reconfigure() for both init and the sysctl updates, but I >> can't for my life figure out why that doesn't work. > > I collected the changes which Linus requested along with the nmi_probe() > one and pushed them into: > > git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git WIP.core/urgent > > That's based on 4.13 final so it neither contains 4.14 nor -next material.
Thanks. I tested that here and it seems fine. The warning at boot is gone and it is correctly catching a hard lockup triggered via LKDTM, eg: # mount -t debugfs none /sys/kernel/debug # echo HARDLOCKUP > /sys/kernel/debug/provoke-crash/DIRECT lkdtm: Performing direct entry HARDLOCKUP Watchdog CPU:0 Hard LOCKUP Modules linked in: CPU: 0 PID: 1215 Comm: sh Not tainted 4.13.0-gcc6-11846-g86be5ee #162 task: c0000000f1fc4c00 task.stack: c0000000ee3ac000 NIP: c0000000007205a4 LR: c00000000071f950 CTR: c000000000720570 REGS: c00000003ffffd80 TRAP: 0900 Not tainted (4.13.0-gcc6-11846-g86be5ee) MSR: 9000000000009033 <SF,HV,EE,ME,IR,DR,RI,LE> CR: 28002228 XER: 00000000 CFAR: c0000000007205a8 SOFTE: 0 GPR00: c00000000071f950 c0000000ee3afbb0 c00000000107cf00 c0000000010604f0 GPR04: c0000000ffa05d90 c0000000ffa1c968 0000000000000000 0000000000000000 GPR08: 0000000000000007 0000000000000001 0000000000000000 9000000030001003 GPR12: c000000000720570 c00000000fd40000 0000000000000000 0000000000000000 GPR16: 0000000000000000 0000000000000000 0000000000000000 00000000100b8fd0 GPR20: 000001002f5a3485 00000000100b8f90 0000000000000000 0000000000000000 GPR24: c000000001060778 c0000000ee3afe00 c0000000ee3afe00 c0000000010603b0 GPR28: 000000000000000b c0000000f1fe0000 0000000000000140 c0000000010604f0 NIP [c0000000007205a4] lkdtm_HARDLOCKUP+0x34/0x40 LR [c00000000071f950] lkdtm_do_action+0x50/0x70 Call Trace: [c0000000ee3afbb0] [0000000000000140] 0x140 (unreliable) [c0000000ee3afbd0] [c00000000071f950] lkdtm_do_action+0x50/0x70 [c0000000ee3afc00] [c00000000071fdc0] direct_entry+0x110/0x1b0 [c0000000ee3afc90] [c00000000050141c] full_proxy_write+0x9c/0x110 [c0000000ee3afcf0] [c000000000336a3c] __vfs_write+0x6c/0x210 [c0000000ee3afd90] [c000000000338960] vfs_write+0xd0/0x270 [c0000000ee3afde0] [c00000000033a93c] SyS_write+0x6c/0x110 [c0000000ee3afe30] [c00000000000b220] system_call+0x58/0x6c Instruction dump: 3842c990 7c0802a6 f8010010 f821ffe1 60000000 60000000 39400000 892d027a 994d027a 60000000 60420000 7c210b78 <7c421378> 4bfffff8 60420000 3c4c0096 Kernel panic - not syncing: Hard LOCKUP Acked-by: Michael Ellerman <m...@ellerman.id.au> (powerpc) cheers