Messages in this thread | | | From | "Rafael J. Wysocki" <> | Date | Wed, 21 Sep 2022 20:28:45 +0200 | Subject | Re: [PATCH] thermal/drivers/intel_powerclamp: Fix bug for smp_processor_id |
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On Tue, Sep 20, 2022 at 1:07 PM Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com> wrote: > > When CPU 0 is offline and intel_powerclamp is used to inject > idle, it generates kernel BUG: > > BUG: using smp_processor_id() in preemptible [00000000] code: bash/15687 > caller is debug_smp_processor_id+0x17/0x20 > CPU: 4 PID: 15687 Comm: bash Not tainted 5.19.0-rc7+ #57 > Call Trace: > <TASK> > dump_stack_lvl+0x49/0x63 > dump_stack+0x10/0x16 > check_preemption_disabled+0xdd/0xe0 > debug_smp_processor_id+0x17/0x20 > powerclamp_set_cur_state+0x7f/0xf9 [intel_powerclamp] > ... > ... > > Here CPU 0 is the control CPU by default and changed to the current CPU, > if CPU 0 offlined. This check has to be performed under cpus_read_lock(), > hence the above warning. > > Use get_cpu() instead of smp_processor_id() to avoid this BUG. > > Suggested-by: Chen Yu <yu.c.chen@intel.com> > Signed-off-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com> > --- > drivers/thermal/intel/intel_powerclamp.c | 6 ++++-- > 1 file changed, 4 insertions(+), 2 deletions(-) > > diff --git a/drivers/thermal/intel/intel_powerclamp.c b/drivers/thermal/intel/intel_powerclamp.c > index c841ab37e7c6..46cd799af148 100644 > --- a/drivers/thermal/intel/intel_powerclamp.c > +++ b/drivers/thermal/intel/intel_powerclamp.c > @@ -532,8 +532,10 @@ static int start_power_clamp(void) > > /* prefer BSP */ > control_cpu = 0; > - if (!cpu_online(control_cpu)) > - control_cpu = smp_processor_id(); > + if (!cpu_online(control_cpu)) { > + control_cpu = get_cpu(); > + put_cpu(); > + } > > clamping = true; > schedule_delayed_work(&poll_pkg_cstate_work, 0); > --
Applied as 6.1 material with modified subject, thanks!
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