On Thu, Aug 21, 2008 at 6:49 PM, Vegard Nossum <vegard.nossum@gmail.com> wrote:
quoted text
> But I think it would be a lot more useful to see _everything_. Why
> doesn't output to ttyS0 work? It works with tty0... I have tried
> various combinations (leaving out console=tty0, leaving out
> earlyprintk, using netconsole, kexec crashdump), but nothing seems to
> be able to help. Do you have any suggestions?

I did it!

With a little debug patch, I got the oops to ttyS0, but with each
printk() duplicated (I removed some of them). This is from resume:

BUG: unable to handle kernel BUG: unable to handle kernel paging
requestpaging request at 00200200
 at 00200200
IP:IP: [<c038accc>] list_del+0xc/0x90
 [<c038accc>] list_del+0xc/0x90
*pdpt = 00000000331a0001 *pde = 0000000000000000
Oops: 0000 [#1] Oops: 0000 [#1] PREEMPT PREEMPT SMP SMP
DEBUG_PAGEALLOCDEBUG_PAGEALLOC
Pid: 3473, comm: bash Not tainted (2.6.27-rc4-00003-ga798564-dirty #30)
EIP: 0060:[<c038accc>] EFLAGS: 00210082 CPU: 0
EIP is at list_del+0xc/0x90
EAX: 00200200 EBX: f77fcc00 ECX: 00000001 EDX: f31a6000
ESI: c088e814 EDI: c088e83c EBP: f31a7be8 ESP: f31a7bd0
 DS: 007b ES: 007b FS: 00d8 GS: 0033 SS: 0068
Process bash (pid: 3473, ti=f31a6000 task=f30ea700 task.ti=f31a6000)
Stack: Stack: 00000000 00000000 00000002 00000002 00000000 00000000
c01b39be c01b39be f77cefa0 f77cefa0 f77fcbd0 f77fcbd0 f31a7bfc
f31a7bfc c01b39ef c01b39ef
              f77cefa0 f77cefa0 00000000 00000000 c1133598 c1133598
f31a7c3c f31a7c3c c01b3ebc c01b3ebc c0b530c0 c0b530c0 f31a7c18
f31a7c18 c015b60e c015b60e
              f31a7c18 f31a7c18 ffffffff ffffffff 00000020 00000020
c088e800 c088e800 00200046 00200046 00000000 00000000 00000000
00000000 00000000 00000000
Call Trace:
 [<c01b39be>]  [<c01b39be>] ? ? get_partial_node+0x3e/0xc0
 [<c01b39ef>]  [<c01b39ef>] ? ? get_partial_node+0x6f/0xc0
 [<c01b3ebc>]  [<c01b3ebc>] ? ? __slab_alloc+0x11c/0x4e0
 [<c015b60e>]  [<c015b60e>] ? ? get_lock_stats+0x1e/0x50
 [<c01b5ffc>]  [<c01b5ffc>] ? ? __kmalloc+0x11c/0x130
 [<c03ceeb2>]  [<c03ceeb2>] ? ? tty_buffer_request_room+0xe2/0x130
 [<c03ceeb2>]  [<c03ceeb2>] ? ? tty_buffer_request_room+0xe2/0x130
 [<c03ceeb2>]  [<c03ceeb2>] ? ? tty_buffer_request_room+0xe2/0x130
 [<c03d131d>]  [<c03d131d>] ? ? tty_insert_flip_string_flags+0x2d/0xa0
 [<c03efcf1>]  [<c03efcf1>] ? ? receive_chars+0x161/0x290
 [<c03f0d24>]  [<c03f0d24>] ? ? serial8250_interrupt+0x134/0x150
 [<c017db28>]  [<c017db28>] ? ? handle_IRQ_event+0x28/0x70
 [<c017f0ef>]  [<c017f0ef>] ? ? handle_edge_irq+0xaf/0x140
 [<c0108138>]  [<c0108138>] ? ? do_IRQ+0x48/0xa0
 [<c037b7a4>]  [<c037b7a4>] ? ? trace_hardirqs_off_thunk+0xc/0x18
 [<c0105a3c>]  [<c0105a3c>] ? ? common_interrupt+0x28/0x30
 [<c013b2d1>]  [<c013b2d1>] ? ? vprintk+0x151/0x3c0
 [<c015e884>]  [<c015e884>] ? ? trace_hardirqs_on_caller+0xd4/0x160
 [<c015e91b>]  [<c015e91b>] ? ? trace_hardirqs_on+0xb/0x10
 [<c0687983>]  [<c0687983>] ? ? _spin_unlock_irqrestore+0x43/0x70
 [<c038ef8b>]  [<c038ef8b>] ? ? pci_bus_read_config_byte+0x5b/0x70
 [<c013b55b>]  [<c013b55b>] ? ? printk+0x1b/0x20
 [<c059a748>]  [<c059a748>] ? ? pcibios_set_master+0x68/0xa0
 [<c03925c4>]  [<c03925c4>] ? ? pci_set_master+0x54/0x60
 [<c0513d9c>]  [<c0513d9c>] ? ? usb_hcd_pci_resume+0x4c/0xf0
 [<c015e91b>]  [<c015e91b>] ? ? trace_hardirqs_on+0xb/0x10
 [<c0393cf6>]  [<c0393cf6>] ? ? pci_legacy_resume+0x16/0x30
 [<c0393d5a>]  [<c0393d5a>] ? ? pci_pm_restore+0x4a/0x60
 [<c03f83e5>]  [<c03f83e5>] ? ? pm_op+0x115/0x130
 [<c03f8986>]  [<c03f8986>] ? ? device_resume+0xd6/0x380
 [<c0168791>]  [<c0168791>] ? ? hibernation_snapshot+0xa1/0x220
 [<c013b55b>]  [<c013b55b>] ? ? printk+0x1b/0x20
 [<c01689f0>]  [<c01689f0>] ? ? hibernate+0xe0/0x180
 [<c01674a0>]  [<c01674a0>] ? ? state_store+0x0/0xd0
 [<c016755f>]  [<c016755f>] ? ? state_store+0xbf/0xd0
 [<c01674a0>]  [<c01674a0>] ? ? state_store+0x0/0xd0
 [<c0375ef4>]  [<c0375ef4>] ? ? kobj_attr_store+0x24/0x30
 [<c01fa432>]  [<c01fa432>] ? ? sysfs_write_file+0xa2/0x100
 [<c01bbf06>]  [<c01bbf06>] ? ? vfs_write+0x96/0x130
 [<c01fa390>]  [<c01fa390>] ? ? sysfs_write_file+0x0/0x100
 [<c01bc44d>]  [<c01bc44d>] ? ? sys_write+0x3d/0x70
 [<c0104f3b>]  [<c0104f3b>] ? ? sysenter_do_call+0x12/0x3f
 =======================
Code: Code: e8 e8 01 01 89 89 44 44 24 24 04 04 e8 e8 94 94 08 08 db
db ff ff 8b 8b 55 55 04 04 b8 b8 80 80 45 45 7a 7a c0 c0 e8 e8 e7 e7
c2 c2 dd dd ff ff e8 e8
 a2 a2 c7 c7 d7 d7 ff ff eb eb a9 a9 55 55 89 89 e5 e5 53 53 89 89 c3
c3 83 83 ec ec 14 14 8b 8b 40 40 04 04 <8b> <8b> 00 00 39 39 d8 d8 75
75 24 24 8b 8b 13 13
8b 8b 42 42 04 04 39 39 d8 d8 75 75 41 41 8b 8b 43 43 04 04 89 89 42 42 04 04
EIP: [<c038accc>] EIP: [<c038accc>] list_del+0xc/0x90list_del+0xc/0x90
SS:ESP 0068:f31a7bd0
Kernel panic - not syncing: Fatal exception in interrupt

The EIP corresponds to the first line of list_del, lib/list_debug.c:46:

void list_del(struct list_head *entry)
{
        WARN(entry->prev->next != entry,

I actually have one theory: Data arrives on the serial port at the
wrong moment, so interrupt happens before everything is
restored/resumed. You can see the interrupt in the stack trace. Does
this seem possible?


Vegard

-- 
"The animistic metaphor of the bug that maliciously sneaked in while
the programmer was not looking is intellectually dishonest as it
disguises that the error is the programmer's own creation."
	-- E. W. Dijkstra, EWD1036
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