mm/headers, sched/headers: Move task related MM types from <linux/mm_types.> to <linux/mm_types_task.h>

Separate all the MM types that are embedded directly in 'struct task_struct'
into the <linux/mm_types_task.h> header.

The goal is to include this header in <linux/sched.h>, not the full <linux/mm_types.h>
header, to reduce the size, complexity and coupling of <linux/sched.h>.

(This patch does not change <linux/sched.h> yet.)

Acked-by: Linus Torvalds <[e-mail]>
Cc: Mike Galbraith <[e-mail]>
Cc: Peter Zijlstra <[e-mail]>
Cc: Thomas Gleixner <[e-mail]>
Cc: [e-mail]
Signed-off-by: Ingo Molnar <[e-mail]>

include/linux/mm_types.h

···
 struct address_space;
 struct mem_cgroup;
 
-#define USE_SPLIT_PTE_PTLOCKS	(NR_CPUS >= CONFIG_SPLIT_PTLOCK_CPUS)
-#define USE_SPLIT_PMD_PTLOCKS	(USE_SPLIT_PTE_PTLOCKS && \
-		IS_ENABLED(CONFIG_ARCH_ENABLE_SPLIT_PMD_PTLOCK))
-#define ALLOC_SPLIT_PTLOCKS	(SPINLOCK_SIZE > BITS_PER_LONG/8)
-
 /*
  * Each physical page in the system has a struct page associated with
  * it to keep track of whatever it is we are using the page for at the
···
 #endif
 ;
 
-struct page_frag {
-	struct page *page;
-#if (BITS_PER_LONG > 32) || (PAGE_SIZE >= 65536)
-	__u32 offset;
-	__u32 size;
-#else
-	__u16 offset;
-	__u16 size;
-#endif
-};
-
 #define PAGE_FRAG_CACHE_MAX_SIZE	__ALIGN_MASK(32768, ~PAGE_MASK)
 #define PAGE_FRAG_CACHE_MAX_ORDER	get_order(PAGE_FRAG_CACHE_MAX_SIZE)
 
···
 	struct vm_userfaultfd_ctx vm_userfaultfd_ctx;
 };
 
-/*
- * The per task VMA cache array:
- */
-#define VMACACHE_BITS 2
-#define VMACACHE_SIZE (1U << VMACACHE_BITS)
-#define VMACACHE_MASK (VMACACHE_SIZE - 1)
-
-struct vmacache {
-	u32 seqnum;
-	struct vm_area_struct *vmas[VMACACHE_SIZE];
-};
-
 struct core_thread {
 	struct task_struct *task;
 	struct core_thread *next;
···
 	atomic_t nr_threads;
 	struct core_thread dumper;
 	struct completion startup;
-};
-
-enum {
-	MM_FILEPAGES,	/* Resident file mapping pages */
-	MM_ANONPAGES,	/* Resident anonymous pages */
-	MM_SWAPENTS,	/* Anonymous swap entries */
-	MM_SHMEMPAGES,	/* Resident shared memory pages */
-	NR_MM_COUNTERS
-};
-
-#if USE_SPLIT_PTE_PTLOCKS && defined(CONFIG_MMU)
-#define SPLIT_RSS_COUNTING
-/* per-thread cached information, */
-struct task_rss_stat {
-	int events;	/* for synchronization threshold */
-	int count[NR_MM_COUNTERS];
-};
-#endif /* USE_SPLIT_PTE_PTLOCKS */
-
-struct mm_rss_stat {
-	atomic_long_t count[NR_MM_COUNTERS];
 };
 
 struct kioctx_table;

include/linux/mm_types_task.h

···
 #ifndef _LINUX_MM_TYPES_TASK_H
 #define _LINUX_MM_TYPES_TASK_H
 
+/*
+ * Here are the definitions of the MM data types that are embedded in 'struct task_struct'.
+ *
+ * (These are defined separately to decouple sched.h from mm_types.h as much as possible.)
+ */
+
 #include <linux/types.h>
 #include <linux/threads.h>
 #include <linux/atomic.h>
 
 #include <asm/page.h>
+
+#define USE_SPLIT_PTE_PTLOCKS	(NR_CPUS >= CONFIG_SPLIT_PTLOCK_CPUS)
+#define USE_SPLIT_PMD_PTLOCKS	(USE_SPLIT_PTE_PTLOCKS && \
+		IS_ENABLED(CONFIG_ARCH_ENABLE_SPLIT_PMD_PTLOCK))
+#define ALLOC_SPLIT_PTLOCKS	(SPINLOCK_SIZE > BITS_PER_LONG/8)
+
+/*
+ * The per task VMA cache array:
+ */
+#define VMACACHE_BITS 2
+#define VMACACHE_SIZE (1U << VMACACHE_BITS)
+#define VMACACHE_MASK (VMACACHE_SIZE - 1)
+
+struct vmacache {
+	u32 seqnum;
+	struct vm_area_struct *vmas[VMACACHE_SIZE];
+};
+
+enum {
+	MM_FILEPAGES,	/* Resident file mapping pages */
+	MM_ANONPAGES,	/* Resident anonymous pages */
+	MM_SWAPENTS,	/* Anonymous swap entries */
+	MM_SHMEMPAGES,	/* Resident shared memory pages */
+	NR_MM_COUNTERS
+};
+
+#if USE_SPLIT_PTE_PTLOCKS && defined(CONFIG_MMU)
+#define SPLIT_RSS_COUNTING
+/* per-thread cached information, */
+struct task_rss_stat {
+	int events;	/* for synchronization threshold */
+	int count[NR_MM_COUNTERS];
+};
+#endif /* USE_SPLIT_PTE_PTLOCKS */
+
+struct mm_rss_stat {
+	atomic_long_t count[NR_MM_COUNTERS];
+};
+
+struct page_frag {
+	struct page *page;
+#if (BITS_PER_LONG > 32) || (PAGE_SIZE >= 65536)
+	__u32 offset;
+	__u32 size;
+#else
+	__u16 offset;
+	__u16 size;
+#endif
+};
 
 #endif /* _LINUX_MM_TYPES_TASK_H */