Re: Checkin 7404ad3b6d04efbd918e9e2e776bf560fbedf47d breaks booton KVM
From: H. Peter Anvin
Date: Tue Oct 14 2008 - 12:01:30 EST
James Bottomley wrote:
Actually, it is surprising. That patch takes the default arithmetic for
calculating the disk size out of sd and uses a routine to do it more
efficiently in lib/string_helpers.c
So there are two problems: Why does it panic on revert (could you post
the oops) and what does kvm object to in string_get_size ... it's a
fairly innocuous routine as I read it ... your symptoms sound like the
for loop isn't terminating.
Here is the oops. Note that it does get well past the hang point before
it crashes. It is 100% reproducible.
console [netcon0] enabled
netconsole: network logging started
Uniform Multi-Platform E-IDE driver
ide-floppy driver 1.00
Driver 'sd' needs updating - please use bus_type methods
scsi0 : ata_piix
scsi1 : ata_piix
ata1: PATA max MWDMA2 cmd 0x1f0 ctl 0x3f6 bmdma 0xc000 irq 14
ata2: PATA max MWDMA2 cmd 0x170 ctl 0x376 bmdma 0xc008 irq 15
ata1.00: ATA-7: QEMU HARDDISK, 0.9.1, max UDMA/100
ata1.00: 16777216 sectors, multi 16: LBA48
ata1.00: configured for MWDMA2
ata2.00: ATAPI: QEMU DVD-ROM, 0.9.1, max UDMA/100
ata2.00: configured for MWDMA2
scsi 0:0:0:0: Direct-Access ATA QEMU HARDDISK 0.9. PQ: 0
ANSI: 5
sd 0:0:0:0: [sda] 16777216 512-byte hardware sectors (8590 MB)
sd 0:0:0:0: [sda] Write Protect is off
sd 0:0:0:0: [sda] Write cache: disabled, read cache: enabled, doesn't
support DPO or FUA
sd 0:0:0:0: [sda] 16777216 512-byte hardware sectors (8590 MB)
sd 0:0:0:0: [sda] Write Protect is off
sd 0:0:0:0: [sda] Write cache: disabled, read cache: enabled, doesn't
support DPO or FUA
sda: sda1
sd 0:0:0:0: [sda] Attached SCSI disk
scsi 1:0:0:0: CD-ROM QEMU QEMU DVD-ROM 0.9. PQ: 0
ANSI: 5
PNP: PS/2 Controller [PNP0303:KBD,PNP0f13:MOU] at 0x60,0x64 irq 1,12
serio: i8042 KBD port at 0x60,0x64 irq 1
serio: i8042 AUX port at 0x60,0x64 irq 12
mice: PS/2 mouse device common for all mice
input: AT Translated Set 2 keyboard as /class/input/input0
md: linear personality registered for level -1
md: raid0 personality registered for level 0
md: raid1 personality registered for level 1
md: raid10 personality registered for level 10
raid6: int32x1 972 MB/s
raid6: int32x2 1032 MB/s
raid6: int32x4 763 MB/s
raid6: int32x8 729 MB/s
raid6: mmxx1 2572 MB/s
raid6: mmxx2 3154 MB/s
raid6: sse1x1 2036 MB/s
raid6: sse1x2 2430 MB/s
raid6: sse2x1 3506 MB/s
raid6: sse2x2 3428 MB/s
raid6: using algorithm sse2x1 (3506 MB/s)
md: raid6 personality registered for level 6
md: raid5 personality registered for level 5
md: raid4 personality registered for level 4
EDAC MC: Ver: 2.1.0 Oct 13 2008
input: ImExPS/2 Generic Explorer Mouse as /class/input/input1
dcdbas dcdbas: Dell Systems Management Base Driver (version 5.6.0-3.2)
usbcore: registered new interface driver hiddev
usbcore: registered new interface driver usbhid
usbhid: v2.6:USB HID core driver
TCP cubic registered
NET: Registered protocol family 17
RPC: Registered udp transport module.
RPC: Registered tcp transport module.
Using IPI Shortcut mode
registered taskstats version 1
BIOS EDD facility v0.16 2004-Jun-25, 1 devices found
md: Autodetecting RAID arrays.
md: Scanned 0 and added 0 devices.
md: autorun ...
md: ... autorun DONE.
kjournald starting. Commit interval 5 seconds
EXT3-fs: mounted filesystem with ordered data mode.
VFS: Mounted root (ext3 filesystem) readonly.
Freeing unused kernel memory: 304k freed
Write protecting the kernel text: 3692k
Write protecting the kernel read-only data: 1556k
BUG: spinlock bad magic on CPU#0, swapper/1
lock: c0b75418, .magic: 00000000, .owner: <none>/-1, .owner_cpu: 0
Pid: 1, comm: swapper Not tainted 2.6.27 #17
Call Trace:
[<c0597388>] ? printk+0xf/0x17
[<c03ac8ae>] spin_bug+0x75/0x80
[<c03ac97c>] _raw_spin_lock+0x1e/0xe4
[<c0412a3f>] ? serial8250_startup+0x33e/0x4e5
[<c0599821>] _spin_lock_irq+0x32/0x3a
[<c0412a3f>] ? serial8250_startup+0x33e/0x4e5
[<c0412a3f>] serial8250_startup+0x33e/0x4e5
[<c040f5fb>] uart_startup+0x84/0x143
[<c0410309>] uart_open+0x14b/0x381
[<c05996ba>] ? _spin_unlock+0x27/0x3c
[<c03f483f>] ? check_tty_count+0x3b/0x8a
[<c03f70b9>] tty_open+0x263/0x366
[<c0271b2a>] chrdev_open+0x168/0x180
[<c026df19>] __dentry_open+0x146/0x234
[<c026e08e>] nameidata_to_filp+0x1f/0x33
[<c02719c2>] ? chrdev_open+0x0/0x180
[<c0278ed1>] do_filp_open+0x342/0x659
[<c023651c>] ? trace_hardirqs_off+0xb/0xd
[<c05996ba>] ? _spin_unlock+0x27/0x3c
[<c026dcff>] do_sys_open+0x42/0xb7
[<c026ddb6>] sys_open+0x1e/0x26
[<c0201216>] init_post+0x2a/0x13c
[<c0203d53>] ? kernel_thread_helper+0x7/0x10
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