| Message ID | 3772609.tskOqDLWI3@aspire.rjw.lan (mailing list archive) |
|---|---|
| State | Superseded, archived |
| Headers | show |
> >--------- Original Message --------- >Sender : Rafael J. Wysocki <rjw@rjwysocki.net> >Date : 2017-06-01 08:58 (GMT+9) >Title : Re: FW: [4.12 regression] "cpufreq: intel_pstate: Active mode P-state limits rework" > >On Monday, May 29, 2017 02:18:52 AM Jongman Heo wrote: >> >> Hi, >> >> FYI, 4.12-rc3 still has this issue. >> >> >> --------- Original Message --------- >> Sender : 허종만 <jongman.heo@samsung.com> >> Date : 2017-05-16 13:25 (GMT+9) >> Title : [4.12 regression] "cpufreq: intel_pstate: Active mode P-state limits rework" >> >> >> Hi, >> >> With 4.12-rc1 (Linus git), booting fails due to kernel panic, at intel_pstate_register_driver+0x56/0x110. >> I can't copy the whole trace from the graphic console, it looks like below. >> >> Call Trace: >> intel_pstate_init >> intel_pstate_setup >> do_one_initcall >> set_debug_rodata >> kernel_init_freeable >> rest_init >> kernel_init >> ret_from_fork >> Code: ... >> RIP: intel_pstate_register_driver+0x56/0x110 RSP: ffffa3a98000bd80 >> ... > >I guess this is a division by 0 due to the unmet assumption that the denominator >in min_perf_pct_min() will always be nonzero. > >If this guess is correct, the patch below should help, so can you please test it? > >Thanks, >Rafael > > >--- > drivers/cpufreq/intel_pstate.c | 5 +++-- > 1 file changed, 3 insertions(+), 2 deletions(-) > >Index: linux-pm/drivers/cpufreq/intel_pstate.c >=================================================================== >--- linux-pm.orig/drivers/cpufreq/intel_pstate.c >+++ linux-pm/drivers/cpufreq/intel_pstate.c >@@ -571,9 +571,10 @@ static inline void update_turbo_state(vo > static int min_perf_pct_min(void) > { > struct cpudata *cpu = all_cpu_data[0]; >+ int turbo_pstate = cpu->pstate.turbo_pstate; > >- return DIV_ROUND_UP(cpu->pstate.min_pstate * 100, >- cpu->pstate.turbo_pstate); >+ return turbo_pstate ? >+ DIV_ROUND_UP(cpu->pstate.min_pstate * 100, turbo_pstate) : 0; > } > > static s16 intel_pstate_get_epb(struct cpudata *cpu_data) > > > Hi, Your patch fixes the issue. Thanks~. Jongman.
Index: linux-pm/drivers/cpufreq/intel_pstate.c =================================================================== --- linux-pm.orig/drivers/cpufreq/intel_pstate.c +++ linux-pm/drivers/cpufreq/intel_pstate.c @@ -571,9 +571,10 @@ static inline void update_turbo_state(vo static int min_perf_pct_min(void) { struct cpudata *cpu = all_cpu_data[0]; + int turbo_pstate = cpu->pstate.turbo_pstate; - return DIV_ROUND_UP(cpu->pstate.min_pstate * 100, - cpu->pstate.turbo_pstate); + return turbo_pstate ? + DIV_ROUND_UP(cpu->pstate.min_pstate * 100, turbo_pstate) : 0; } static s16 intel_pstate_get_epb(struct cpudata *cpu_data)