Messages in this thread | | | Date | Tue, 28 Jun 2011 16:08:37 +0100 | From | Marc Zyngier <> | Subject | [next][bug] rcu_dyntick_kick_cpu() kills ARM SMP. |
| |
Paul,
I've updated my -next tree (to next-20110628) today, and discovered that my favorite ARM board wouldn't boot anymore:
[...] Hierarchical RCU implementation. NR_IRQS:128 nr_irqs:128 128 Console: colour dummy device 80x30 Calibrating delay loop... 83.35 BogoMIPS (lpj=416768) pid_max: default: 32768 minimum: 301 Mount-cache hash table entries: 512 CPU: Testing write buffer coherency: ok Calibrating local timer... 104.04MHz. CPU1: Booted secondary processor CPU1: Unknown IPI message 0x1 CPU2: Booted secondary processor CPU2: Unknown IPI message 0x1 CPU3: Booted secondary processor CPU3: Unknown IPI message 0x1 Brought up 4 CPUs SMP: Total of 4 processors activated (333.92 BogoMIPS). ------------[ cut here ]------------ WARNING: at kernel/smp.c:320 smp_call_function_single+0xe4/0x1c0() NET: Registered protocol family 16 Modules linked in: [<c00415d4>] (unwind_backtrace+0x0/0xf4) from [<c0056184>] (warn_slowpath_common+0x4c/0x64) [<c0056184>] (warn_slowpath_common+0x4c/0x64) from [<c00561b8>] (warn_slowpath_null+0x1c/0x24) [<c00561b8>] (warn_slowpath_null+0x1c/0x24) from [<c0088218>] (smp_call_function_single+0xe4/0x1c0) [<c0088218>] (smp_call_function_single+0xe4/0x1c0) from [<c0094804>] (rcu_start_gp+0x184/0x310) [<c0094804>] (rcu_start_gp+0x184/0x310) from [<c00955b0>] (__rcu_process_callbacks+0x274/0x398) [<c00955b0>] (__rcu_process_callbacks+0x274/0x398) from [<c0095708>] (rcu_process_callbacks+0x34/0x5c) [<c0095708>] (rcu_process_callbacks+0x34/0x5c) from [<c005c964>] (__do_softirq+0xa4/0x16c) [<c005c964>] (__do_softirq+0xa4/0x16c) from [<c005cc0c>] (irq_exit+0x80/0x9c) [<c005cc0c>] (irq_exit+0x80/0x9c) from [<c00353cc>] (do_local_timer+0x54/0x70) [<c00353cc>] (do_local_timer+0x54/0x70) from [<c003b618>] (__irq_svc+0x38/0xc0) Exception stack(0xdf467f90 to 0xdf467fd8) 7f80: df466000 00000000 df467fd8 00000000 7fa0: df466000 c045dd24 c034f6cc 00000000 c0445514 410fb020 70409ddc 00000000 7fc0: 00000000 df467fd8 c003c4ac c003c4b0 60000013 ffffffff [<c003b618>] (__irq_svc+0x38/0xc0) from [<c003c4b0>] (default_idle+0x24/0x28) [<c003c4b0>] (default_idle+0x24/0x28) from [<c003ccd0>] (cpu_idle+0x9c/0xdc) [<c003ccd0>] (cpu_idle+0x9c/0xdc) from [<70348734>] (0x70348734) ---[ end trace 1b75b31a2719ed1c ]---
... and here it dies.
The offending commit is b983032b7 (rcu: Avoid grace-period overflow for long dyntick-idle periods). rcu_dyntick_kick_cpu() tries to do a CPU cross-call with interrupts disabled, which kills the box. Reverting this patch results in a working system.
My RCU-foo being rather low, I haven't dug deeper into this. Please let me know if you want me to test anything.
Cheers,
M. -- Jazz is not dead. It just smells funny...
| |