On Fri 21-05-21 17:46:04, Andreas Gruenbacher wrote:

On Fri, May 21, 2021 at 5:23 PM Jan Kara [off-list ref] wrote:

quoted

On Thu 20-05-21 16:07:56, Andreas Gruenbacher wrote:

quoted

quoted

So you probably need to add a new VM_FAULT_
return code that will behave like VM_FAULT_SIGBUS except it will not raise
the signal.

A new VM_FAULT_* flag might make the code easier to read, but I don't
know if we can have one.

Well, this is kernel-internal API and there's still plenty of space in
vm_fault_reason.

That's in the context of the page fault. The other issue is how to
propagate that out through iov_iter_fault_in_readable ->
fault_in_pages_readable -> __get_user, for example. I don't think
there's much of a chance to get an additional error code out of
__get_user and __put_user.

Yes, at that level we'd get EFAULT as in any other case. Really the only
difference of the new VM_FAULT_ error code from a case of "standard" error
and VM_FAULT_SIGBUS would be not raising the signal.

								Honza
-- 
Jan Kara [off-list ref]
SUSE Labs, CR