Re: Lockups with 4.2-rc kernels and qemu

[Ken Moffat]

On Tue, Aug 25, 2015 at 12:40:15AM +0100, Ken Moffat wrote:
> (Cc'ing qemu-devel, please keep me in the Cc).
> 
> TL;DR - qemu locks up my machine when I use 4.2-rc kernels.
> 
Previous mail, or at least the copy to qemu, archived at
https://lists.gnu.org/archive/html/qemu-devel/2015-08/msg02784.html

I started bisecting, but it is going to be a slow business - kernels
which seem to be ok after e.g. 3 hours can still lock the box.  I
left it running overnight, and this morning it was still up - but
firefox could no longer connect externally.  I eventually tracked
that to my logs taking the space.  But one reason the logs had
become so big was the following (found from this morning's restart):

Aug 27 09:50:28 ac4tv kernel: [  124.279813] BUG: scheduling while
atomic: qemu-system-x86/1789/0x00000002
Aug 27 09:50:28 ac4tv kernel: [  124.279819] Modules linked in:
psmouse i2c_piix4 asus_atk0110 microcode k10temp
Aug 27 09:50:28 ac4tv kernel: [  124.279828] Preemption disabled
at:[<ffffffff8100787c>] kvm_vcpu_ioctl+0x7c/0x580
Aug 27 09:50:28 ac4tv kernel: [  124.279839] 
Aug 27 09:50:28 ac4tv kernel: [  124.279842] CPU: 2 PID: 1789 Comm:
qemu-system-x86 Not tainted 4.1.0-10762-g8c7febe #4
Aug 27 09:50:28 ac4tv kernel: [  124.279843] Hardware name: System
manufacturer System Product Name/M5A78L-M LX V2, BIOS 0601
11/30/2011
Aug 27 09:50:28 ac4tv kernel: [  124.279845]  ffff88021fd14880
ffff88020718fc38 ffffffff8178316e 0000000080000002
Aug 27 09:50:28 ac4tv kernel: [  124.279847]  0000000000014880
ffff88020718fc48 ffffffff810b93d7 ffff88020718fca8
Aug 27 09:50:28 ac4tv kernel: [  124.279849]  ffffffff8178607c
ffff88021fc14880 ffff880215ebc100 ffff88020718fc78
Aug 27 09:50:28 ac4tv kernel: [  124.279851] Call Trace:
Aug 27 09:50:28 ac4tv kernel: [  124.279855]  [<ffffffff8178316e>]
dump_stack+0x4f/0x7b
Aug 27 09:50:28 ac4tv kernel: [  124.279859]  [<ffffffff810b93d7>]
__schedule_bug+0x57/0xa0
Aug 27 09:50:28 ac4tv kernel: [  124.279861]  [<ffffffff8178607c>]
__schedule+0x67c/0x9d0
Aug 27 09:50:28 ac4tv kernel: [  124.279864]  [<ffffffff8178b008>] ?
_raw_write_unlock_irqrestore+0x18/0x40
Aug 27 09:50:28 ac4tv kernel: [  124.279865]  [<ffffffff817864b1>]
schedule+0x41/0x90
Aug 27 09:50:28 ac4tv kernel: [  124.279867]  [<ffffffff81786888>]
schedule_preempt_disabled+0x18/0x30
Aug 27 09:50:28 ac4tv kernel: [  124.279869]  [<ffffffff81788f9d>]
__mutex_lock_slowpath+0x10d/0x340
Aug 27 09:50:28 ac4tv kernel: [  124.279871]  [<ffffffff817891e6>]
mutex_lock+0x16/0x30
Aug 27 09:50:28 ac4tv kernel: [  124.279874]  [<ffffffff8115c4c2>]
static_key_slow_inc+0x42/0xc0
Aug 27 09:50:28 ac4tv kernel: [  124.279875]  [<ffffffff810b92dd>]
preempt_notifier_register+0x1d/0x60
Aug 27 09:50:28 ac4tv kernel: [  124.279881]  [<ffffffff8100774d>]
vcpu_load+0x4d/0x90
Aug 27 09:50:28 ac4tv kernel: [  124.279887]  [<ffffffff8100787c>]
kvm_vcpu_ioctl+0x7c/0x580
Aug 27 09:50:28 ac4tv kernel: [  124.279892]  [<ffffffff8178af77>] ?
_raw_write_unlock_irq+0x17/0x40
Aug 27 09:50:28 ac4tv kernel: [  124.279898]  [<ffffffff811bb445>]
do_vfs_ioctl+0x295/0x480
Aug 27 09:50:28 ac4tv kernel: [  124.279905]  [<ffffffff811c5189>] ?
__fget+0x79/0xb0
Aug 27 09:50:28 ac4tv kernel: [  124.279910]  [<ffffffff811bb67c>]
SyS_ioctl+0x4c/0x90
Aug 27 09:50:28 ac4tv kernel: [  124.279914]  [<ffffffff8115cf23>] ?
context_tracking_user_enter+0x13/0x20
Aug 27 09:50:28 ac4tv kernel: [  124.279917]  [<ffffffff8105c055>] ?
syscall_trace_leave+0xa5/0x140
Aug 27 09:50:28 ac4tv kernel: [  124.279919]  [<ffffffff8178b657>]
entry_SYSCALL_64_fastpath+0x12/0x6a
Aug 27 09:50:28 ac4tv kernel: [  124.477786] kvm: zapping shadow
pages for mmio generation wraparound
Aug 27 09:50:31 ac4tv kernel: [  127.177303] BUG: scheduling while
atomic: qemu-system-x86/1788/0x00000002
Aug 27 09:50:31 ac4tv kernel: [  127.177309] Modules linked in:
Aug 27 09:50:31 ac4tv kernel: [  127.177317] BUG: scheduling while
atomic: qemu-system-x86/1790/0x00000002
Aug 27 09:50:31 ac4tv kernel: [  127.177318]  psmouse i2c_piix4
asus_atk0110 microcode k10temp
Aug 27 09:50:31 ac4tv kernel: [  127.177332] Preemption disabled at:
Aug 27 09:50:31 ac4tv kernel: [  127.177334] Modules linked in:
psmouse i2c_piix4 asus_atk0110 microcode k10temp
Aug 27 09:50:31 ac4tv kernel: [  127.177341] Preemption disabled
at:[<ffffffff8100787c>] kvm_vcpu_ioctl+0x7c/0x580
 etc, etc.

I have not _noticed_ these messages on -rc8, but for the moment I am
inclined to treat them as another sign of the same problem.  Which
means a fresh bisection.  <sigh/>

Äen
-- 
This one goes up to eleven: but only on a clear day, with the wind in
the right direction.
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