Re: d57108d4f6 ("watchdog/core: Get rid of the thread .."): BUG: unable to handle kernel NULL pointer dereference at 0000000000000208

On Sat, Sep 16, 2017 at 2:47 PM, Thomas Gleixner wrote: > > Yes and no. We get more code which uses cpumasks to store state, just like > I did, and while a lot of the cpumask functions just work as expected a > subset including for_each_cpu does not. That's confusing at best

Re: d57108d4f6 ("watchdog/core: Get rid of the thread .."): BUG: unable to handle kernel NULL pointer dereference at 0000000000000208

On Sat, Sep 16, 2017 at 2:47 PM, Thomas Gleixner wrote: > > Yes and no. We get more code which uses cpumasks to store state, just like > I did, and while a lot of the cpumask functions just work as expected a > subset including for_each_cpu does not. That's confusing at best and I > rather avoid

Re: d57108d4f6 ("watchdog/core: Get rid of the thread .."): BUG: unable to handle kernel NULL pointer dereference at 0000000000000208

On Sat, 16 Sep 2017, Linus Torvalds wrote: > On Sat, Sep 16, 2017 at 11:12 AM, Thomas Gleixner wrote: > >> > >> So I suspect your perf fix is the right one, and maybe we could/should > >> just make people more aware of the empty cpumask issue with UP. > > > > Right, I just got

Re: d57108d4f6 ("watchdog/core: Get rid of the thread .."): BUG: unable to handle kernel NULL pointer dereference at 0000000000000208

On Sat, 16 Sep 2017, Linus Torvalds wrote: > On Sat, Sep 16, 2017 at 11:12 AM, Thomas Gleixner wrote: > >> > >> So I suspect your perf fix is the right one, and maybe we could/should > >> just make people more aware of the empty cpumask issue with UP. > > > > Right, I just got a bit frightened as

Re: d57108d4f6 ("watchdog/core: Get rid of the thread .."): BUG: unable to handle kernel NULL pointer dereference at 0000000000000208

On Sat, Sep 16, 2017 at 11:12 AM, Thomas Gleixner wrote: >> >> So I suspect your perf fix is the right one, and maybe we could/should >> just make people more aware of the empty cpumask issue with UP. > > Right, I just got a bit frightened as I really was not aware about that

Re: d57108d4f6 ("watchdog/core: Get rid of the thread .."): BUG: unable to handle kernel NULL pointer dereference at 0000000000000208

On Sat, Sep 16, 2017 at 11:12 AM, Thomas Gleixner wrote: >> >> So I suspect your perf fix is the right one, and maybe we could/should >> just make people more aware of the empty cpumask issue with UP. > > Right, I just got a bit frightened as I really was not aware about that > 'opmtimization'

Re: d57108d4f6 ("watchdog/core: Get rid of the thread .."): BUG: unable to handle kernel NULL pointer dereference at 0000000000000208

On Sat, 16 Sep 2017, Linus Torvalds wrote: > On Sat, Sep 16, 2017 at 10:35 AM, Thomas Gleixner wrote: > > > > Don't bother. I found it already. On UP we have: > > > > #define for_each_cpu(cpu, mask) \ > > for ((cpu) = 0; (cpu) < 1; (cpu)++, (void)mask) >

Re: d57108d4f6 ("watchdog/core: Get rid of the thread .."): BUG: unable to handle kernel NULL pointer dereference at 0000000000000208

On Sat, 16 Sep 2017, Linus Torvalds wrote: > On Sat, Sep 16, 2017 at 10:35 AM, Thomas Gleixner wrote: > > > > Don't bother. I found it already. On UP we have: > > > > #define for_each_cpu(cpu, mask) \ > > for ((cpu) = 0; (cpu) < 1; (cpu)++, (void)mask) > > > > which is a

Re: d57108d4f6 ("watchdog/core: Get rid of the thread .."): BUG: unable to handle kernel NULL pointer dereference at 0000000000000208

On Sat, Sep 16, 2017 at 10:35 AM, Thomas Gleixner wrote: > > Don't bother. I found it already. On UP we have: > > #define for_each_cpu(cpu, mask) \ > for ((cpu) = 0; (cpu) < 1; (cpu)++, (void)mask) > > which is a total fail as it breaks any code which

Re: d57108d4f6 ("watchdog/core: Get rid of the thread .."): BUG: unable to handle kernel NULL pointer dereference at 0000000000000208

On Sat, Sep 16, 2017 at 10:35 AM, Thomas Gleixner wrote: > > Don't bother. I found it already. On UP we have: > > #define for_each_cpu(cpu, mask) \ > for ((cpu) = 0; (cpu) < 1; (cpu)++, (void)mask) > > which is a total fail as it breaks any code which uses for_each_cpu() or

Re: d57108d4f6 ("watchdog/core: Get rid of the thread .."): BUG: unable to handle kernel NULL pointer dereference at 0000000000000208

On Sat, 16 Sep 2017, Fengguang Wu wrote: > > > [0.038086] Performance Events: unsupported p6 CPU model 61 no PMU > > > driver, software events only. > > What's your host CPU? I can reproduce it in Nehalem, Haswell and Sandy > Bridge machines with the attached script. My bad. I booted the

Re: d57108d4f6 ("watchdog/core: Get rid of the thread .."): BUG: unable to handle kernel NULL pointer dereference at 0000000000000208

On Sat, 16 Sep 2017, Fengguang Wu wrote: > > > [0.038086] Performance Events: unsupported p6 CPU model 61 no PMU > > > driver, software events only. > > What's your host CPU? I can reproduce it in Nehalem, Haswell and Sandy > Bridge machines with the attached script. My bad. I booted the

Re: d57108d4f6 ("watchdog/core: Get rid of the thread .."): BUG: unable to handle kernel NULL pointer dereference at 0000000000000208

On Fri, Sep 15, 2017 at 06:24:20PM +0200, Thomas Gleixner wrote: On Fri, 15 Sep 2017, Thomas Gleixner wrote: On Fri, 15 Sep 2017, Thomas Gleixner wrote: > On Fri, 15 Sep 2017, kernel test robot wrote: > > [0.035023] CPU: Intel Common KVM processor (family: 0xf, model: 0x6, stepping: 0x1)

Re: d57108d4f6 ("watchdog/core: Get rid of the thread .."): BUG: unable to handle kernel NULL pointer dereference at 0000000000000208

On Fri, Sep 15, 2017 at 06:24:20PM +0200, Thomas Gleixner wrote: On Fri, 15 Sep 2017, Thomas Gleixner wrote: On Fri, 15 Sep 2017, Thomas Gleixner wrote: > On Fri, 15 Sep 2017, kernel test robot wrote: > > [0.035023] CPU: Intel Common KVM processor (family: 0xf, model: 0x6, stepping: 0x1)

Re: d57108d4f6 ("watchdog/core: Get rid of the thread .."): BUG: unable to handle kernel NULL pointer dereference at 0000000000000208

On Fri, 15 Sep 2017, Thomas Gleixner wrote: > On Fri, 15 Sep 2017, Thomas Gleixner wrote: > > > On Fri, 15 Sep 2017, kernel test robot wrote: > > > [0.035023] CPU: Intel Common KVM processor (family: 0xf, model: 0x6, > > > stepping: 0x1) > > > [0.042302] Performance Events: unsupported

Re: d57108d4f6 ("watchdog/core: Get rid of the thread .."): BUG: unable to handle kernel NULL pointer dereference at 0000000000000208

On Fri, 15 Sep 2017, Thomas Gleixner wrote: > On Fri, 15 Sep 2017, Thomas Gleixner wrote: > > > On Fri, 15 Sep 2017, kernel test robot wrote: > > > [0.035023] CPU: Intel Common KVM processor (family: 0xf, model: 0x6, > > > stepping: 0x1) > > > [0.042302] Performance Events: unsupported

Re: d57108d4f6 ("watchdog/core: Get rid of the thread .."): BUG: unable to handle kernel NULL pointer dereference at 0000000000000208

On Fri, 15 Sep 2017, Thomas Gleixner wrote: > On Fri, 15 Sep 2017, kernel test robot wrote: > > [0.035023] CPU: Intel Common KVM processor (family: 0xf, model: 0x6, > > stepping: 0x1) > > [0.042302] Performance Events: unsupported Netburst CPU model 6 no PMU > > driver, software events

Re: d57108d4f6 ("watchdog/core: Get rid of the thread .."): BUG: unable to handle kernel NULL pointer dereference at 0000000000000208

On Fri, 15 Sep 2017, Thomas Gleixner wrote: > On Fri, 15 Sep 2017, kernel test robot wrote: > > [0.035023] CPU: Intel Common KVM processor (family: 0xf, model: 0x6, > > stepping: 0x1) > > [0.042302] Performance Events: unsupported Netburst CPU model 6 no PMU > > driver, software events

Re: d57108d4f6 ("watchdog/core: Get rid of the thread .."): BUG: unable to handle kernel NULL pointer dereference at 0000000000000208

On Fri, 15 Sep 2017, kernel test robot wrote: > [0.035023] CPU: Intel Common KVM processor (family: 0xf, model: 0x6, > stepping: 0x1) > [0.042302] Performance Events: unsupported Netburst CPU model 6 no PMU > driver, software events only. Cute. So there is no supported PMU, but for some

Re: d57108d4f6 ("watchdog/core: Get rid of the thread .."): BUG: unable to handle kernel NULL pointer dereference at 0000000000000208

On Fri, 15 Sep 2017, kernel test robot wrote: > [0.035023] CPU: Intel Common KVM processor (family: 0xf, model: 0x6, > stepping: 0x1) > [0.042302] Performance Events: unsupported Netburst CPU model 6 no PMU > driver, software events only. Cute. So there is no supported PMU, but for some

d57108d4f6 ("watchdog/core: Get rid of the thread .."): BUG: unable to handle kernel NULL pointer dereference at 0000000000000208

Greetings, 0day kernel testing robot got the below dmesg and the first bad commit is https://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git master commit d57108d4f6791291e89d980e7f7a3566c32ab188 Author: Thomas Gleixner AuthorDate: Tue Sep 12 21:37:11 2017 +0200

d57108d4f6 ("watchdog/core: Get rid of the thread .."): BUG: unable to handle kernel NULL pointer dereference at 0000000000000208

Greetings, 0day kernel testing robot got the below dmesg and the first bad commit is https://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git master commit d57108d4f6791291e89d980e7f7a3566c32ab188 Author: Thomas Gleixner AuthorDate: Tue Sep 12 21:37:11 2017 +0200 Commit: Ingo Molnar