get_mempolicy(): store policy in per-process VM structure

kernel/include/process.h

@@ -168,6 +168,15 @@
 
 #define PROCESS_NUMA_MASK_BITS 64
 
+enum {
+	MPOL_DEFAULT,
+	MPOL_PREFERRED,
+	MPOL_BIND,
+	MPOL_INTERLEAVE,
+	MPOL_LOCAL,
+	MPOL_MAX,	/* always last member of enum */
+};
+
 #include <waitq.h>
 #include <futex.h>
 
@@ -598,6 +607,7 @@ struct process_vm {
 
 	long currss;
 	DECLARE_BITMAP(numa_mask, PROCESS_NUMA_MASK_BITS);
+	int numa_mem_policy;
 };
 
 static inline int has_cap_ipc_lock(struct thread *th)

kernel/process.c

@@ -223,6 +223,7 @@ init_process_vm(struct process *owner, struct address_space *asp, struct process
 		}
 		set_bit(i, &vm->numa_mask[0]);
 	}
+	vm->numa_mem_policy = MPOL_DEFAULT;
 
 	return 0;
 }
@@ -384,6 +385,8 @@ clone_thread(struct thread *org, unsigned long pc, unsigned long sp,
 		}
 		memcpy(&proc->vm->numa_mask, &org->vm->numa_mask,
 				sizeof(proc->vm->numa_mask));
+		proc->vm->numa_mem_policy =
+			org->vm->numa_mem_policy;
 
 		thread->proc = proc;
 		thread->vm = proc->vm;

kernel/syscall.c

@@ -7077,16 +7077,6 @@ out:
 	return error;
 } /* sys_getcpu() */
 
-/* XXX: move this to header.. */
-enum {
-	MPOL_DEFAULT,
-	MPOL_PREFERRED,
-	MPOL_BIND,
-	MPOL_INTERLEAVE,
-	MPOL_LOCAL,
-	MPOL_MAX,	/* always last member of enum */
-};
-
 SYSCALL_DECLARE(mbind)
 {
 	return -ENOSYS;
@@ -7112,7 +7102,9 @@ SYSCALL_DECLARE(get_mempolicy)
 	}
 
 	if (mode) {
-		error = copy_to_user(mode, MPOL_DEFAULT, sizeof(*mode));
+		error = copy_to_user(mode,
+				&cpu_local_var(current)->vm->numa_mem_policy,
+				sizeof(int));
 		if (error) {
 			error = -EINVAL;
 			goto out;