[S390] protect _PAGE_SPECIAL bit against mprotect
[S390] protect _PAGE_SPECIAL bit against mprotect

Stop mprotect's pte_modify from wiping out the s390 pte_special bit, which
caused oops thereafter when vm_normal_page thought X's abnormal was normal.

Debugged-by: Ryan Hope <d257ac7320d0414f4196fc00f8b579c9d1c3bf9a@gmail.com>
Debugged-by: Zan Lynx <94847c0afb2269fa416551f44448144243cc108c@acm.org>
Acked-by: Hugh Dickins <a6c5230a10c458028ff1bd5985dd47c394028d47@veritas.com>
Signed-off-by: Nick Piggin <24829078df5003d9dd1dd871ca2aeb0b1cf95ef4@suse.de>
Signed-off-by: Martin Schwidefsky <52616596d8f5df0d597e85ab515377f92f939c68@de.ibm.com>

TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs