I do often experiencing deadlock while copying large amounts of data 
drom USB camera.

I am not sure what subsystem is guilty, it may be either USB, SCSI, FAT 
or something I do not imagine.

Kernel 2.4.20 from ftp.kernel.org compiled with gcc 3.2.1 (as from 
ftp.gcc.org). USB, SCSI and FAT compiled as modules.
.config is attached.

Camera is Sony DSC-P9, it supports USB mass storage.
Media in the camera - memory stick 128Mb, FAT; bug appears when copying 
some 50+ Mb, usually when CPU is busy with some background process.

Process that copy files get stalled in __lock_page function. Besides 
this, everything continue to work. After reboot copy wents well.

I captured situation when 'mc' (midnight commander) get stalled; and got 
kernel stack information using Ctl+Alt+SysRq+T. Attached file contains 
stack for 'mc' task, plus sorted 'ksyms'.

I am able and will be glad to do kernel modifications and/or provide 
additional information if I will know what to look for.

Regards, Vladimir.