RE: [PATCH v2] x86/mce: set MCE_IN_KERNEL_COPYIN for all MC-Safe Copy

[Luck, Tony]

> As mentioned above, I am focus on copy_mc_XXX calling, it will
> abort if the exception fires when accessing the source, and we
> want to isolate the corrupted src page, maybe we could a new flag
> to indicate this scenario, the *Final Goals* is to let core
> do_machine_check to deal with the corrupted src page.

A new flag seems like a good direction. Re-using the existing
MCE_IN_KERNEL_COPYIN one happens to work now, but
is causing confusing now (since this case isn't a copy-from-user)
and may cause code maintenance issues in the future.

-Tony