Messages in this thread | | | Date | Fri, 11 Dec 2009 16:23:59 +0530 | From | Sachin Sant <> | Subject | [Next] CPU Hotplug test failures on powerpc |
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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
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
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--------------------------------- Sachin Sant IBM Linux Technology Center India Systems and Technology Labs Bangalore, India ---------------------------------
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