On 10/06/2012 05:06 PM, Michael Wang wrote: > On 09/26/2012 11:41 AM, Michael Wang wrote: >> On 09/18/2012 11:13 AM, Michael Wang wrote: >>> This patch try to fix the BUG: >>> >>> [ 0.043953] BUG: scheduling while atomic: swapper/0/1/0x10000002 >>> [ 0.044017] no locks held by swapper/0/1. >>> [ 0.044692] Pid: 1, comm: swapper/0 Not tainted 3.6.0-rc1-00420-gb7aebb9 >>> #34 >>> [ 0.045861] Call Trace: >>> [ 0.048071] [<c106361e>] __schedule_bug+0x5e/0x70 >>> [ 0.048890] [<c1b28701>] __schedule+0x91/0xb10 >>> [ 0.049660] [<c14472ea>] ? vsnprintf+0x33a/0x450 >>> [ 0.050444] [<c1060006>] ? lg_local_lock+0x6/0x70 >>> [ 0.051256] [<c14fb5b1>] ? wait_for_xmitr+0x31/0x90 >>> [ 0.052019] [<c144fd55>] ? do_raw_spin_unlock+0xa5/0xf0 >>> [ 0.052903] [<c1b2a532>] ? _raw_spin_unlock+0x22/0x30 >>> [ 0.053759] [<c105cdbb>] ? up+0x1b/0x70 >>> [ 0.054421] [<c1065d6b>] __cond_resched+0x1b/0x30 >>> [ 0.055228] [<c1b292d5>] _cond_resched+0x45/0x50 >>> [ 0.056020] [<c1b26c58>] mutex_lock_nested+0x28/0x370 >>> [ 0.056884] [<c1034222>] ? console_unlock+0x3a2/0x4e0 >>> [ 0.057741] [<c1ac8559>] __irq_alloc_descs+0x39/0x1c0 >>> [ 0.058589] [<c10223bc>] io_apic_setup_irq_pin+0x2c/0x310 >>> [ 0.060042] [<c20638df>] setup_IO_APIC+0x101/0x744 >>> [ 0.060878] [<c1021d51>] ? clear_IO_APIC+0x31/0x50 >>> [ 0.061695] [<c20600f4>] native_smp_prepare_cpus+0x538/0x680 >>> [ 0.062644] [<c2056a91>] ? do_one_initcall+0x12c/0x12c >>> [ 0.063517] [<c2056a91>] ? do_one_initcall+0x12c/0x12c >>> [ 0.064016] [<c2056adc>] kernel_init+0x4b/0x17f >>> [ 0.064790] [<c2056a91>] ? do_one_initcall+0x12c/0x12c >>> [ 0.065660] [<c1b2bbd6>] kernel_thread_helper+0x6/0x10 >>> >>> The process to trigger the BUG is: >>> >>> native_smp_prepare_cpus() >>> preempt_disable() //preempt_count++ >>> __irq_alloc_descs() >>> mutex_lock() >>> might_sleep() //should_resched() return true >>> __schedule() >>> preempt_disable() //preempt_count++ >>> schedule_bug() //preempt_count > 1, report bug >>> >>> So the issue is that should_resched() should not return true while the >>> preempt >>> already disabled. >> >> Hi, Peter >> >> Could we use this solution to fix the bug? > > Please tell me if it's wrong, I really want to help fix it.
Reset the destination, sorry for the terrible mailing skill... Regards, Michael Wang > > Regards, > Michael Wang > >> >> Regards, >> Michael Wang >> >>> >>> This patch will fix the issue, then might_sleep() won't do schedule in >>> atomic >>> any more. >>> >>> Reported-by: Fengguang Wu <w...@linux.intel.com> >>> Signed-off-by: Michael Wang <wang...@linux.vnet.ibm.com> >>> --- >>> kernel/sched/core.c | 2 +- >>> 1 files changed, 1 insertions(+), 1 deletions(-) >>> >>> diff --git a/kernel/sched/core.c b/kernel/sched/core.c >>> index b38f00e..2b7cd15 100644 >>> --- a/kernel/sched/core.c >>> +++ b/kernel/sched/core.c >>> @@ -4171,7 +4171,7 @@ SYSCALL_DEFINE0(sched_yield) >>> >>> static inline int should_resched(void) >>> { >>> - return need_resched() && !(preempt_count() & PREEMPT_ACTIVE); >>> + return need_resched() && !preempt_count(); >>> } >>> >>> static void __cond_resched(void) >>> >> > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/