[Techtalk] BUG: soft lockup detected on CPU#0!

David Sumbler david at aeolia.co.uk
Sat Apr 7 09:49:14 UTC 2007

A friend of mine bought a Lenovo N100 laptop computer about 4 months
ago.  This has twin processors, and came with Ubuntu 6.06 and Windows XP
installed on it.  She uses Linux now, loves it, and regrets having paid
extra to have XP installed.  It is certainly a lovely machine.

Unfortunately, occasionally it goes into mega-go-slow mode.  When this
happened yesterday I logged into her machine and, after looking at "top"
etc. I found the following at the end of the 'dmesg' output.

[17214216.700000] BUG: soft lockup detected on CPU#0!
[17214216.700000] Pid: 0, comm:              swapper
[17214216.700000] EIP: 0060:[<c012b93f>] CPU: 0
[17214216.700000] EIP is at __do_softirq+0x5f/0xe0
[17214216.700000]  EFLAGS: 00000202    Tainted: P       (2.6.15-28-686)
[17214216.700000] EAX: 01085f60 EBX: 00000020 ECX: c03a6000 EDX:
[17214216.700000] ESI: c03a0f40 EDI: c03fdee0 EBP: 0000000a DS: 007b ES:
[17214216.700000] CR0: 8005003b CR2: b6f1b000 CR3: 1a55a000 CR4:
[17214216.700000]  [<c014f54c>] __do_IRQ+0xcc/0x110
[17214216.700000]  [<c012b9f5>] do_softirq+0x35/0x40
[17214216.700000]  [<c012bad5>] irq_exit+0x45/0x50
[17214216.700000]  [<c0105c8e>] do_IRQ+0x1e/0x30
[17214216.700000]  [<c0103ebe>] common_interrupt+0x1a/0x20
[17214216.700000]  [<e0853e9b>] acpi_processor_idle+0x184/0x32d
[17214216.700000]  [<c010111f>] cpu_idle+0x6f/0xc0
[17214216.700000]  [<c03aca3f>] start_kernel+0x19f/0x200
[17214216.700000]  [<c03ac3c0>] unknown_bootoption+0x0/0x1f0
[17214251.144000] BUG: soft lockup detected on CPU#0!
[17214251.144000] Pid: 0, comm:              swapper
[17214251.144000] EIP: 0060:[<e0853e9b>] CPU: 0
[17214251.144000] EIP is at acpi_processor_idle+0x184/0x32d [processor]
[17214251.144000]  EFLAGS: 00000246    Tainted: P       (2.6.15-28-686)
[17214251.144000] EAX: ffffe000 EBX: 0019d499 ECX: 0019d0bf EDX:
[17214251.144000] ESI: deae60bc EDI: deae6000 EBP: 0047d007 DS: 007b ES:
[17214251.144000] CR0: 8005003b CR2: b7f84fdc CR3: 003ff000 CR4:
[17214251.144000]  [<c010111f>] cpu_idle+0x6f/0xc0
[17214251.144000]  [<c03aca3f>] start_kernel+0x19f/0x200
[17214251.144000]  [<c03ac3c0>] unknown_bootoption+0x0/0x1f0

Although I have just quoted the last two, there were actually numerous
such entries, at intervals of a few seconds to a few minutes.

Can anyone shed any light as to what is causing the problem?

One suggestion that was made to me is that the driver which I installed
for my friend's USB ADSL modem could be to blame, as it may be written
only for a single processor.  Is that likely to be the case?

One other thing: on a couple of previous occasions when the computer
slowed down, 'top' seemed to show that the problem was Evolution 2.6.1
(which is standard with Ubuntu 6.06), and which had taken huge amounts
of memory.  I have looked to see if this bug is reported anywhere, but
can't find any reference to it, which is very odd.  Could the apparently
more fundamental problem shown by 'dmesg' somehow be causing Evolution
occasionally to misbehave?

I'd be very grateful for any suggestions.


David Sumbler <david at aeolia.co.uk>

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