Hi,
So I tried to play around a little bit with this patchset. I did a
checkout from:
git://linux-arm.org/linux-power.git energy_model_rfc_v4
and then, when I tried to enable the ENERGY_AWARE from sysfs inside
qemu (x86_64) and I got this:
[69452.750245] BUG: unable to handle kernel paging request at ffff88009d3fb958
[69452.750245] IP: [<ffffffff8107b8b5>] try_to_wake_up+0x125/0x310
[69452.750245] PGD 2155067 PUD 0
[69452.750245] Oops: 0000 [#1] SMP
[69452.750245] Modules linked in:
[69452.750245] CPU: 0 PID: 1007 Comm: sh Not tainted 4.1.0-rc2+ #8
[69452.750245] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996),
BIOS 1.8.1-20150318_183358- 04/01/2014
[69452.750245] task: ffff88007c9e5aa0 ti: ffff88007be0c000 task.ti:
ffff88007be0c000
[69452.750245] RIP: 0010:[<ffffffff8107b8b5>] [<ffffffff8107b8b5>]
try_to_wake_up+0x125/0x310
[69452.750245] RSP: 0000:ffff88007fc03d78 EFLAGS: 00000092
[69452.750245] RAX: 00000000ffffffff RBX: 00000000ffffffff RCX: 0000000000015a40
[69452.750245] RDX: 0000000000000001 RSI: 0000000000000000 RDI: ffff88007d005000
[69452.750245] RBP: ffff88007fc03dc8 R08: 0000000000000400 R09: 0000000000000000
[69452.750245] R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000015a40
[69452.750245] R13: ffff88007d3fbdaa R14: 0000000000000000 R15: ffff88007d3fb660
[69452.750245] FS: 00007f8a3c9f0700(0000) GS:ffff88007fc00000(0000)
knlGS:0000000000000000
[69452.750245] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[69452.750245] CR2: ffff88009d3fb958 CR3: 000000007c32c000 CR4: 00000000000006f0
[69452.750245] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[69452.750245] DR3: 0000000000000000 DR6: 0000000000000000 DR7: 0000000000000000
[69452.750245] Stack:
[69452.750245] ffff88007fc15aa8 ffff88007c9e5b08 ffff88007fc15aa8
0000000000000046
[69452.750245] ffff88007fc03e08 ffff88007c83fe60 ffffffff81e3c8a8
ffffffff81e3c890
[69452.750245] 0000000000000000 0000000000000003 ffff88007fc03dd8
ffffffff8107bb8d
[69452.750245] Call Trace:
[69452.750245] <IRQ>
[69452.750245] [<ffffffff8107bb8d>] default_wake_function+0xd/0x10
[69452.750245] [<ffffffff8108ed21>] autoremove_wake_function+0x11/0x40
[69452.750245] [<ffffffff8108e6b5>] __wake_up_common+0x55/0x90
[69452.750245] [<ffffffff8108e728>] __wake_up+0x38/0x60
[69452.750245] [<ffffffff810ab062>] rcu_gp_kthread_wake+0x42/0x50
[69452.750245] [<ffffffff810acd9f>] rcu_process_callbacks+0x2ef/0x5e0
[69452.750245] [<ffffffff81056e0f>] __do_softirq+0x9f/0x280
[69452.750245] [<ffffffff81057145>] irq_exit+0xa5/0xb0
[69452.750245] [<ffffffff81038bd1>] smp_apic_timer_interrupt+0x41/0x50
[69452.750245] [<ffffffff818ae5bb>] apic_timer_interrupt+0x6b/0x70
[69452.750245] <EOI>
[69452.750245] Code: 4c 89 ff ff d0 41 83 bf f8 02 00 00 01 41 8b 5f
48 7e 16 49 8b 47 60 89 de 44 89 f1 ba 10 00 00 00 4c 89 ff ff 50 40
89 c3 89 d8 <49> 0f a3 87 00 03 00 00 19 d2 85 d2 0f 84 59 01 00 00 48
8b 15
[69452.750245] RIP [<ffffffff8107b8b5>] try_to_wake_up+0x125/0x310
[69452.750245] RSP <ffff88007fc03d78>
[69452.750245] CR2: ffff88009d3fb958
[69452.750245] ---[ end trace 9b4570a93c243e98 ]---
[69452.750245] Kernel panic - not syncing: Fatal exception in interrupt
[69452.750245] Kernel Offset: disabled
[69452.750245] ---[ end Kernel panic - not syncing: Fatal exception in interrupt
and then I did a disassable from kgdb and I got this:
0xffffffff8107b8ae <+286>: callq *0x40(%rax)
0xffffffff8107b8b1 <+289>: mov %eax,%ebx
0xffffffff8107b8b3 <+291>: mov %ebx,%eax
0xffffffff8107b8b5 <+293>: bt %rax,0x300(%r15)
0xffffffff8107b8bd <+301>: sbb %edx,%edx
and then I did a objdump and got this:
static inline
int select_task_rq(struct task_struct *p, int cpu, int sd_flags, int wake_flags)
{
if (p->nr_cpus_allowed > 1)
7dcb: 7e 16 jle 7de3 <try_to_wake_up+0x123>
cpu = p->sched_class->select_task_rq(p, cpu, sd_flags,
wake_flags);
7dcd: 49 8b 47 60 mov 0x60(%r15),%rax
7dd1: 89 de mov %ebx,%esi
7dd3: 44 89 f1 mov %r14d,%ecx
7dd6: ba 10 00 00 00 mov $0x10,%edx
7ddb: 4c 89 ff mov %r15,%rdi
7dde: ff 50 40 callq *0x40(%rax)
7de1: 89 c3 mov %eax,%ebx
7de3: 89 d8 mov %ebx,%eax
7de5: 49 0f a3 87 00 03 00 bt %rax,0x300(%r15)
7dec: 00
7ded: 19 d2 sbb %edx,%edx
* Since this is common to all placement strategies, this lives here.
*
* [ this allows ->select_task() to simply return task_cpu(p) and
* not worry about this generic constraint ]
*/
if (unlikely(!cpumask_test_cpu(cpu, tsk_cpus_allowed(p)) ||
7def: 85 d2 test %edx,%edx
I wasn't able to determine the cause from the line:
7de5: 49 0f a3 87 00 03 00 bt %rax,0x300(%r15)
Finally, the question I have is: Could this happen because I'm running
it from qemu?
I hope all this info helps.
Thanks,
Abel.
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