With CONFIG_PREEMPT=y on an SMP AMD (2CPU):
Sleeping function called from illegal context at /kernel/l-2.5.39/include/asm/semaphore.h:119
c1b75e20 c0117094 c0280b00 c028d480 00000077 c1b41cf0 c016bcf9 c028d480
00000077 c1b41c50 ffffffea c1b74000 00001000 c01937c6 c02e9578 c1b41cf0
c1b41c50 f7f0b840 c1b75eda c018ad0a c1b41c50 c02e9578 00000020 00000000
Call Trace:
[<c0117094>]__might_sleep+0x54/0x58
[<c016bcf9>]driverfs_create_file+0x39/0xa0
[<c01937c6>]device_create_file+0x26/0x40
[<c018ad0a>]pci_pool_create+0xea/0x170
[<c02034af>]hcd_buffer_create+0x3f/0x80
[<c02039c3>]usb_hcd_pci_probe+0x253/0x370
[<c01563d8>]alloc_inode+0x58/0x190
[<c018b751>]pci_device_probe+0x41/0x60
[<c0191b88>]probe+0x18/0x30
[<c0191c2b>]found_match+0x2b/0x60
[<c0191d57>]do_driver_attach+0x37/0x50
[<c019296c>]bus_for_each_dev+0x9c/0x130
[<c0191d83>]driver_attach+0x13/0x20
[<c0191d20>]do_driver_attach+0x0/0x50
[<c0192ee4>]driver_register+0x94/0xb0
[<c018b856>]pci_register_driver+0x36/0x50
[<c01050b7>]init+0x47/0x1c0
[<c0105070>]init+0x0/0x1c0
[<c010553d>]kernel_thread_helper+0x5/0x18