nodemask: Split out include/linux/nodemask_types.h

sched.h, which defines task_struct, needs nodemask_t - but sched.h is a
frequently used header and ideally shouldn't be pulling in any more code
that it needs to.

This splits out nodemask_types.h which has the definition sched.h needs,
which will avoid a circular header dependency in the alloc tagging patch
series, and as a bonus should speed up kernel build times.
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
Signed-off-by: Suren Baghdasaryan <surenb@google.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>

include/linux/nodemask.h

@@ -93,10 +93,10 @@
 #include <linux/threads.h>
 #include <linux/bitmap.h>
 #include <linux/minmax.h>
+#include <linux/nodemask_types.h>
 #include <linux/numa.h>
 #include <linux/random.h>
 
-typedef struct { DECLARE_BITMAP(bits, MAX_NUMNODES); } nodemask_t;
 extern nodemask_t _unused_nodemask_arg_;
 
 /**

include/linux/nodemask_types.h

+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef __LINUX_NODEMASK_TYPES_H
+#define __LINUX_NODEMASK_TYPES_H
+
+#include <linux/bitops.h>
+#include <linux/numa.h>
+
+typedef struct { DECLARE_BITMAP(bits, MAX_NUMNODES); } nodemask_t;
+
+#endif /* __LINUX_NODEMASK_TYPES_H */

include/linux/sched.h

@@ -20,7 +20,7 @@
 #include <linux/hrtimer.h>
 #include <linux/irqflags.h>
 #include <linux/seccomp.h>
-#include <linux/nodemask.h>
+#include <linux/nodemask_types.h>
 #include <linux/rcupdate.h>
 #include <linux/refcount.h>
 #include <linux/resource.h>