flush_tlb_mm's "optimized" uniprocessor case of allocating a new
context for userspace is exposing a race where we can suddely return
to a syscall with the protection id and space id out of sync, trapping
on the next userspace access.
Debugged-by: NJames Bottomley <James.Bottomley@HansenPartnership.com>
Tested-by: NHelge Deller <deller@gmx.de>
Signed-off-by: NKyle McMartin <kyle@mcmartin.ca>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>