mm: replace access_process_vm() write parameter with gup_flags

This removes the 'write' argument from access_process_vm() and replaces
it with 'gup_flags' as use of this function previously silently implied
FOLL_FORCE, whereas after this patch callers explicitly pass this flag.

We make this explicit as use of FOLL_FORCE can result in surprising
behaviour (and hence bugs) within the mm subsystem.

Signed-off-by: Lorenzo Stoakes <lstoakes@gmail.com>
Acked-by: Jesper Nilsson <jesper.nilsson@axis.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Acked-by: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

arch/blackfin/kernel/ptrace.c

@@ -271,7 +271,7 @@ long arch_ptrace(struct task_struct *child, long request,
 			case BFIN_MEM_ACCESS_CORE:
 			case BFIN_MEM_ACCESS_CORE_ONLY:
 				copied = access_process_vm(child, addr, &tmp,
-				                           to_copy, 0);
+							   to_copy, FOLL_FORCE);
 				if (copied)
 					break;
 
@@ -324,7 +324,8 @@ long arch_ptrace(struct task_struct *child, long request,
 			case BFIN_MEM_ACCESS_CORE:
 			case BFIN_MEM_ACCESS_CORE_ONLY:
 				copied = access_process_vm(child, addr, &data,
-				                           to_copy, 1);
+				                           to_copy,
+							   FOLL_FORCE | FOLL_WRITE);
 				break;
 			case BFIN_MEM_ACCESS_DMA:
 				if (safe_dma_memcpy(paddr, &data, to_copy))