flags are initialized as FAULT_FLAG_DEFAULT, and the only thing done
to that afterwards is |=; since FAULT_FLAG_DEFAULT already includes
FAULT_FLAG_ALLOW_RETRY, it's guaranteed to remain there all along.
Reviewed-by: Guo Ren (Alibaba Damo Academy) <guoren@kernel.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>