On Fri, Dec 11, 2009 at 6:53 PM, Sachin Sant <sachinp@xxxxxxxxxx> wrote: > While executing cpu_hotplug(from autotest) tests against latest > next on a power6 box, the machine locks up. A soft reset shows > the following trace > > cpu 0x0: Vector: 100 (System Reset) at [c00000000c9333d0] > pc: c0000000003433d8: .find_next_bit+0x54/0xc4 > lr: c000000000342f10: .cpumask_next_and+0x4c/0x94 > sp: c00000000c933650 > msr: 8000000000089032 > current = 0xc00000000c173840 > paca = 0xc000000000bc2600 > pid = 2602, comm = hotplug06.top.s > enter ? for help > [link register ] c000000000342f10 .cpumask_next_and+0x4c/0x94 > [c00000000c933650] c0000000000e9f34 .cpuset_cpus_allowed_locked+0x38/0x74 > (unreliable) > [c00000000c9336e0] c000000000090074 .move_task_off_dead_cpu+0xc4/0x1ac > [c00000000c9337a0] c0000000005e4e5c .migration_call+0x304/0x830 > [c00000000c933880] c0000000005e0880 .notifier_call_chain+0x68/0xe0 > [c00000000c933920] c00000000012a92c ._cpu_down+0x210/0x34c > [c00000000c933a90] c00000000012aad8 .cpu_down+0x70/0xa8 > [c00000000c933b20] c000000000525940 .store_online+0x54/0x894 > [c00000000c933bb0] c000000000463430 .sysdev_store+0x3c/0x50 > [c00000000c933c20] c0000000001f8320 .sysfs_write_file+0x124/0x18c > [c00000000c933ce0] c00000000017edac .vfs_write+0xd4/0x1fc > [c00000000c933d80] c00000000017efdc .SyS_write+0x58/0xa0 > [c00000000c933e30] c0000000000085b4 syscall_exit+0x0/0x40 > --- Exception: c01 (System Call) at 00000fff9fa8a8f8 > SP (fffe7aef200) is in userspace > 0:mon> e > cpu 0x0: Vector: 100 (System Reset) at [c00000000c9333d0] > pc: c0000000003433d8: .find_next_bit+0x54/0xc4 > lr: c000000000342f10: .cpumask_next_and+0x4c/0x94 > sp: c00000000c933650 > msr: 8000000000089032 > current = 0xc00000000c173840 > paca = 0xc000000000bc2600 > pid = 2602, comm = hotplug06.top.s > Does this testcase hotplug cpu 0 off? > Last few messages from the dmesg log shows > > 0:mon> <4>IRQ 17 affinity broken off cpu 0 > <4>IRQ 18 affinity broken off cpu 0 > <4>IRQ 19 affinity broken off cpu 0 > <4>IRQ 264 affinity broken off cpu 0 > <4>cpu 0 (hwid 0) Ready to die... > <7>clockevent: decrementer mult[83126e97] shift[32] cpu[0] > <4>Processor 0 found. > <4>IRQ 17 affinity broken off cpu 1 > <4>IRQ 18 affinity broken off cpu 1 > <4>IRQ 19 affinity broken off cpu 1 > <4>IRQ 264 affinity broken off cpu 1 > <4>cpu 1 (hwid 1) Ready to die... > <7>clockevent: decrementer mult[83126e97] shift[32] cpu[1] > <4>Processor 1 found. > <4>cpu 1 (hwid 1) Ready to die... > <7>clockevent: decrementer mult[83126e97] shift[32] cpu[1] > <4>Processor 1 found. > <4>cpu 1 (hwid 1) Ready to die... > <6>process 2423 (bash) no longer affine to cpu1 > <7>clockevent: decrementer mult[83126e97] shift[32] cpu[1] > <4>Processor 1 found. > <4>cpu 1 (hwid 1) Ready to die... > <7>clockevent: decrementer mult[83126e97] shift[32] cpu[1] > <4>Processor 1 found. > <4>cpu 1 (hwid 1) Ready to die... > <7>clockevent: decrementer mult[83126e97] shift[32] cpu[1] > <4>Processor 1 found. > <4>cpu 1 (hwid 1) Ready to die... > <3>INFO: RCU detected CPU 0 stall (t=1000 jiffies) > <3>INFO: RCU detected CPU 0 stall (t=4000 jiffies) > 0:mon> > > After some debugging a possible suspect seems to be commit > 6ad4c18.. : sched: Fix balance vs hotplug race > > If i revert this patch i am able to execute the tests on this > power6 without any issues. > But at the same time the above patch is required to solve the > cpu hotplug related race on x86_64(as a side note this same > x86_64 issue can be recreated against latest Linus git as well) > that i reported here : > > http://marc.info/?l=linux-kernel&m=125802682922299&w=2 > > I will try few more iterations with and without the above > patch just to make sure i have the correct results. > > If someone has a suggestion let me know. > > Thanks > -Sachin > > > -- > > --------------------------------- > Sachin Sant > IBM Linux Technology Center > India Systems and Technology Labs > Bangalore, India > --------------------------------- > > -- > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in > the body of a message to majordomo@xxxxxxxxxxxxxxx > More majordomo info at http://vger.kernel.org/majordomo-info.html > Please read the FAQ at http://www.tux.org/lkml/ > -- To unsubscribe from this list: send the line "unsubscribe linux-next" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
