> On Wed, Oct 10, 2012 at 6:08 PM, Oliver Neukum <[email protected]> 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
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