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Message-ID: <20100208203909.GA6003@rhlx01.hs-esslingen.de> Date: Mon, 8 Feb 2010 21:39:09 +0100 From: Andreas Mohr <andi@...as.de> To: Andreas Mohr <andi@...as.de> Cc: Thomas Gleixner <tglx@...utronix.de>, linux-kernel@...r.kernel.org, Ingo Molnar <mingo@...hat.com>, John Stultz <johnstul@...ibm.com> Subject: Re: clocksource mutex deadlock, cat current_clocksource (2.6.33-rc6/7) Since I'm having trouble pinpointing the reason for the issue (after all divisor is not 0 but likely NSEC_PER_SEC, as likely called by time.h timespec_add_ns() --> __iter_div_u64_rem()), here comes timekeeping_forward_now in its entire glory (objdump -D vmlinux): c104505a <timekeeping_forward_now>: c104505a: 55 push %ebp c104505b: 89 e5 mov %esp,%ebp c104505d: 57 push %edi c104505e: 56 push %esi c104505f: 53 push %ebx c1045060: 83 ec 18 sub $0x18,%esp c1045063: e8 5c dc fb ff call c1002cc4 <mcount> c1045068: 8b 1d d8 20 46 c1 mov 0xc14620d8,%ebx c104506e: 89 d8 mov %ebx,%eax c1045070: ff 53 10 call *0x10(%ebx) c1045073: 8b 4b 1c mov 0x1c(%ebx),%ecx c1045076: 89 c6 mov %eax,%esi c1045078: 89 d7 mov %edx,%edi c104507a: 2b 73 40 sub 0x40(%ebx),%esi c104507d: 1b 7b 44 sbb 0x44(%ebx),%edi c1045080: 21 f1 and %esi,%ecx c1045082: 89 4d ec mov %ecx,-0x14(%ebp) c1045085: 8b 73 20 mov 0x20(%ebx),%esi c1045088: 89 43 40 mov %eax,0x40(%ebx) c104508b: 89 53 44 mov %edx,0x44(%ebx) c104508e: a1 08 21 46 c1 mov 0xc1462108,%eax c1045093: 21 fe and %edi,%esi c1045095: 8b 3d c0 20 46 c1 mov 0xc14620c0,%edi c104509b: 89 45 e4 mov %eax,-0x1c(%ebp) c104509e: 8b 4d e4 mov -0x1c(%ebp),%ecx c10450a1: 8b 45 ec mov -0x14(%ebp),%eax c10450a4: f7 65 e4 mull -0x1c(%ebp) c10450a7: 0f af ce imul %esi,%ecx c10450aa: 89 45 e4 mov %eax,-0x1c(%ebp) c10450ad: 8b 45 e4 mov -0x1c(%ebp),%eax c10450b0: 01 ca add %ecx,%edx c10450b2: 8b 0d dc 20 46 c1 mov 0xc14620dc,%ecx c10450b8: 89 55 e8 mov %edx,-0x18(%ebp) c10450bb: 8b 55 e8 mov -0x18(%ebp),%edx c10450be: 0f ad d0 shrd %cl,%edx,%eax c10450c1: d3 ea shr %cl,%edx c10450c3: f6 c1 20 test $0x20,%cl c10450c6: 74 04 je c10450cc <timekeeping_forward_now+0x72> c10450c8: 89 d0 mov %edx,%eax c10450ca: 31 d2 xor %edx,%edx c10450cc: 89 45 dc mov %eax,-0x24(%ebp) c10450cf: a1 c4 20 46 c1 mov 0xc14620c4,%eax c10450d4: 89 55 e0 mov %edx,-0x20(%ebp) c10450d7: 99 cltd c10450d8: 01 45 dc add %eax,-0x24(%ebp) c10450db: 11 55 e0 adc %edx,-0x20(%ebp) c10450de: 31 c9 xor %ecx,%ecx c10450e0: 8b 45 dc mov -0x24(%ebp),%eax c10450e3: 8b 55 e0 mov -0x20(%ebp),%edx c10450e6: eb 09 jmp c10450f1 <timekeeping_forward_now+0x97> c10450e8: 05 00 36 65 c4 add $0xc4653600,%eax c10450ed: 83 d2 ff adc $0xffffffff,%edx c10450f0: 41 inc %ecx c10450f1: 83 fa 00 cmp $0x0,%edx c10450f4: 77 f2 ja c10450e8 <timekeeping_forward_now+0x8e> c10450f6: 3d ff c9 9a 3b cmp $0x3b9ac9ff,%eax c10450fb: 77 eb ja c10450e8 <timekeeping_forward_now+0x8e> c10450fd: 8b 15 0c 21 46 c1 mov 0xc146210c,%edx c1045103: 8d 3c 39 lea (%ecx,%edi,1),%edi c1045106: 89 3d c0 20 46 c1 mov %edi,0xc14620c0 c104510c: 31 ff xor %edi,%edi c104510e: a3 c4 20 46 c1 mov %eax,0xc14620c4 c1045113: 89 55 e4 mov %edx,-0x1c(%ebp) c1045116: 8b 43 24 mov 0x24(%ebx),%eax c1045119: 31 d2 xor %edx,%edx c104511b: 89 55 e0 mov %edx,-0x20(%ebp) c104511e: 0f af f0 imul %eax,%esi c1045121: 89 45 dc mov %eax,-0x24(%ebp) c1045124: 8b 45 ec mov -0x14(%ebp),%eax c1045127: f7 65 dc mull -0x24(%ebp) c104512a: 01 f2 add %esi,%edx c104512c: 8b 35 10 21 46 c1 mov 0xc1462110,%esi c1045132: 89 45 ec mov %eax,-0x14(%ebp) c1045135: 8b 45 ec mov -0x14(%ebp),%eax c1045138: 89 55 f0 mov %edx,-0x10(%ebp) c104513b: 8b 4b 28 mov 0x28(%ebx),%ecx c104513e: 8b 55 f0 mov -0x10(%ebp),%edx c1045141: 0f ad d0 shrd %cl,%edx,%eax c1045144: d3 ea shr %cl,%edx c1045146: f6 c1 20 test $0x20,%cl c1045149: 0f 45 c2 cmovne %edx,%eax c104514c: 0f 45 d7 cmovne %edi,%edx c104514f: 89 c1 mov %eax,%ecx c1045151: 89 f7 mov %esi,%edi c1045153: 8b 45 e4 mov -0x1c(%ebp),%eax c1045156: 89 d3 mov %edx,%ebx c1045158: c1 ff 1f sar $0x1f,%edi c104515b: 01 f1 add %esi,%ecx c104515d: 11 fb adc %edi,%ebx c104515f: 31 d2 xor %edx,%edx c1045161: eb 0a jmp c104516d <timekeeping_forward_now+0x113> c1045163: 81 c1 00 36 65 c4 add $0xc4653600,%ecx c1045169: 83 d3 ff adc $0xffffffff,%ebx c104516c: 42 inc %edx c104516d: 83 fb 00 cmp $0x0,%ebx c1045170: 77 f1 ja c1045163 <timekeeping_forward_now+0x109> c1045172: 81 f9 ff c9 9a 3b cmp $0x3b9ac9ff,%ecx c1045178: 77 e9 ja c1045163 <timekeeping_forward_now+0x109> c104517a: 89 45 e4 mov %eax,-0x1c(%ebp) c104517d: 8d 04 02 lea (%edx,%eax,1),%eax c1045180: a3 0c 21 46 c1 mov %eax,0xc146210c c1045185: 89 0d 10 21 46 c1 mov %ecx,0xc1462110 c104518b: 83 c4 18 add $0x18,%esp c104518e: 5b pop %ebx c104518f: 5e pop %esi c1045190: 5f pop %edi c1045191: 5d pop %ebp c1045192: c3 ret Note that I got a gcc 4.4 (4.4.2) upgrade, but the problems also occurred at least one build earlier (i.e. with 4.3.4 as standard compiler), as also confirmed by the dpkg installation log and the kernel package timestamp. Plus I'm still wondering how - if it got stuck during boot with an excessively tough division and NMI watchdog triggered - then later in userspace clocksource_mutex was still stuck. And I need to point at nmi_watchdog=2 again, with the CPU being lapic capable but the BIOS not so much, AFAIR. Thanks for the very responsive help! Andreas Mohr -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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