I got linode outage for 2 hours, solved it with restart, linode support says it is php service crash and that my kernel started to panic don't know why it is panicking when all you need is to restart joking. Aynway this is first time for this ever, wondering what could be the cause, which logs file to look? i checked var/log/apache2/error.log and there is nothing, this is from my lish console

NFO: rcu_sched self-detected stall on CPU
3: (2910498 ticks this GP) idle=1c3/140000000000001/0
(t=2940058 jiffies)
Pid: 19638, comm: php5 Tainted: G B D 3.6.5-linode47 #1


[<c01938dd>] ? acct_update_integrals+0x7d/0x130
[<c019204a>] ? __rcu_pending+0xca/0x1b0
[<c01921ef>] ? rcu_check_callbacks+0xbf/0xe0
[<c013e9b5>] ? update_process_times+0x35/0x70
[<c016dbed>] ? tick_sched_timer+0x6d/0xc0
[<c0150db5>] ? __remove_hrtimer+0x45/0xa0
[<c016db80>] ? tick_nohz_handler+0xe0/0xe0
[<c0150f3d>] ? __run_hrtimer+0x4d/0xf0
[<c01513b9>] ? hrtimer_interrupt+0x119/0x2f0
[<c0106887>] ? xen_timer_interrupt+0x17/0x30
[<c018b92f>] ? handle_irq_event_percpu+0x3f/0x150
[<c018ddc5>] ? irq_get_irq_data+0x5/0x10
[<c04e7765>] ? info_for_irq+0x5/0x20
[<c04e7f00>] ? evtchn_from_irq+0x10/0x40
[<c018e081>] ? handle_percpu_irq+0x31/0x50
[<c04e7622>] ? __xen_evtchn_do_upcall+0x162/0x210
[<c04e8a18>] ? xen_evtchn_do_upcall+0x18/0x30
[<c076d887>] ? xen_do_upcall+0x7/0xc
[<c018007b>] ? cpuset_attach+0x17b/0x180
[<c04e00d8>] ? raid6_sse11_gen_syndrome+0xe8/0x100
[<c01013a7>] ? hypercall_page+0x3a7/0x1000
[<c04e7f77>] ? xen_poll_irq_timeout+0x47/0x60
[<c0108245>] ? xen_spin_lock_slow+0x65/0xd0
[<c010830c>] ? xen_spin_lock_flags+0x5c/0x70
[<c076c957>] ? _raw_spin_lock_irqsave+0x27/0x40
[<c01a8e7d>] ? pagevec_lru_move_fn+0x5d/0xb0
[<c01a87b0>] ? pagevec_lookup+0x20/0x20
[<c01a9011>] ? lru_add_drain_cpu+0x61/0xc0
[<c01bd5fb>] ? unmap_region+0x2b/0xc0
[<c01be979>] ? __split_vma+0xd9/0x180
[<c01bebeb>] ? do_munmap+0x1cb/0x2a0
[<c01becf7>] ? vm_munmap+0x37/0x60
[<c076cc21>] ? syscall_call+0x7/0xb
[<c0760000>] ? ceph_str_hash_linux+0x40/0x40

Got same error, but in swapper, exactly a hour after a few-minutes-long outage that I assumed to be a network outage.
Yes, the binary junk on the (1GPs behind) line was real binary junk.

kernel: INFO: rcu_bh self-detected stall on CPU
kernel:         3: (1 GPs behind) idle=1a9/1/0  /^UGûÊrâÿÿÿÿ<Ìò
kernel:          (t=0 jiffies)
kernel: Pid: 0, comm: swapper/3 Not tainted 3.5.2-linode45 #1
kernel: Call Trace:
kernel: [<c018ccba>] ? print_cpu_stall+0xda/0x190
kernel: [<c01215d7>] ? pvclock_clocksource_read+0xf7/0x190
kernel: [<c01215d7>] ? pvclock_clocksource_read+0xf7/0x190
kernel: [<c018ce3a>] ? __rcu_pending+0xca/0x1a0
kernel: [<c018cfd3>] ? rcu_check_callbacks+0xc3/0xd0
kernel: [<c013ac05>] ? update_process_times+0x35/0x70
kernel: [<c0168cf9>] ? tick_sched_timer+0x59/0xb0
kernel: [<c014c6d5>] ? __remove_hrtimer+0x45/0xa0
kernel: [<c0168ca0>] ? tick_nohz_handler+0xe0/0xe0
kernel: [<c014c85d>] ? __run_hrtimer+0x4d/0xf0
kernel: [<c014ccd9>] ? hrtimer_interrupt+0x119/0x2f0
kernel: [<c0106677>] ? xen_timer_interrupt+0x17/0x30
kernel: [<c0186aef>] ? handle_irq_event_percpu+0x3f/0x150
kernel: [<c0188f65>] ? irq_get_irq_data+0x5/0x10
kernel: [<c04c3e05>] ? info_for_irq+0x5/0x20
kernel: [<c04c45a0>] ? evtchn_from_irq+0x10/0x40
kernel: [<c0189221>] ? handle_percpu_irq+0x31/0x50
kernel: [<c04c3cc2>] ? __xen_evtchn_do_upcall+0x162/0x210
kernel: [<c04c50b8>] ? xen_evtchn_do_upcall+0x18/0x30
kernel: [<c072edc7>] ? xen_do_upcall+0x7/0xc
kernel: [<c01013a7>] ? hypercall_page+0x3a7/0x1000
kernel: [<c010606f>] ? xen_safe_halt+0xf/0x20
kernel: [<c011006c>] ? default_idle+0x1c/0x40
kernel: [<c011028a>] ? cpu_idle+0x4a/0x80

_________________
rsk, providing useless advice on the Internet since 2005.