Messages in this thread | | | Date | Tue, 22 Feb 2005 15:41:25 -0500 (EST) | From | Alan Stern <> | Subject | Re: [linux-usb-devel] 2.6: USB Storage hangs machine on bootup for ~2 minutes |
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On Tue, 22 Feb 2005, Parag Warudkar wrote:
> > You said that the system hangs during bootup. Where in the log does that > > hang occur? The log itself looks perfectly normal. The Maxtor drive is > > scanned, the partitions detected, and then apparently one or two > > partitions are mounted. There's no indication of any problem. > > I have tracked down the reason for this hang - it seems that kudzu gets stuck > in D state on usb_device_read - Below SysRQ+T from 2.6.11-rc4 - always > reproducible. > > kudzu D 00000000ffffffff 0 4424 4472 > (NOTLB) > ffff81002bebfd98 0000000000000086 ffff81002c538150 ffff81002f21d00e > 000000078847ce40 ffff81002b5977c0 000000000000fd38 ffffffff803defc0 > ffff81002bebfd88 ffffffff80219b32 > Call Trace: > <ffffffff80219b32>{_atomic_dec_and_lock+290} <ffffffff80383835>{__down+421} > <ffffffff80133e30>{default_wake_function+0} > <ffffffff803868ae>{__down_failed+53} > <ffffffff802db9f1>{.text.lock.usb+5} > <ffffffff802edb35>{usb_device_read+229} > <ffffffff801998d1>{vfs_read+225} <ffffffff80199bd0>{sys_read+80} > <ffffffff8010ed1e>{system_call+126} > > Thereafter, if I try to mount the USB drive, even mount gets stuck.
usb_device_read acquires a couple of locks, one for the USB bus list and one for the root hub of the bus it's looking at. I don't know which one occurs at offset 229 on your system -- maybe you can tell. Oddly enough, neither of those locks is for a USB device like the Maxtor drive. So it's not at all clear why plugging in the drive should mess up kudzu. Or why the blockage should clear up after a couple of minutes.
Perhaps we can find out by looking at other entries in the stack trace. Of particular interest are the khubd, usb-storage, and scsi_eh processes.
Alan Stern
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