> On Wed, Oct 10, 2012 at 6:08 PM, Oliver Neukum <oneukum@xxxxxxx> wrote: > > > A reset always applies to the whole device. Resets are used in error > > handling of block devices (storage and uas). If you reset a device, > > pre_reset() and post_reset() of all interfaces need to be called. So they > > are part of the SCSI error handler. SCSI error handlers can allocate memory > > only with GFP_NOIO (or GFP_ATOMIC) because any IO for paging > > can cause the SCSI layer to wait for the error handling to finish. The error > > handling can only finish when pre/post_reset() have finished. Catch-22 > > IMO, it is not practical to obey the rule for drivers, because driver may > call many other kernel component API which may allocate memory > via GFP_KERNEL in the path easily. What about the error handler/sleep/resume code calling into the memory allocator to indicate that all allocates be GFP_NOIO until it calls back to indicate that the restricted path is complete. Might be a per-cpu count? David -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
