is_vmalloc_addr(): Check if an address is within the vmalloc boundaries

Checking if an address is a vmalloc address is done in a couple of places.
Define a common version in mm.h and replace the other checks.

Again the include structures suck. The definition of VMALLOC_START and
VMALLOC_END is not available in vmalloc.h since highmem.c cannot be included
there.

Signed-off-by: Christoph Lameter <[e-mail]>
Cc: Nick Piggin <[e-mail]>
Signed-off-by: Andrew Morton <[e-mail]>
Signed-off-by: Linus Torvalds <[e-mail]>

drivers/net/cxgb3/cxgb3_offload.c

···
  */
 void cxgb_free_mem(void *addr)
 {
-	unsigned long p = (unsigned long)addr;
-
-	if (p >= VMALLOC_START && p < VMALLOC_END)
+	if (is_vmalloc_addr(addr))
 		vfree(addr);
 	else
 		kfree(addr);

fs/ntfs/malloc.h

···
 
 static inline void ntfs_free(void *addr)
 {
-	if (likely(((unsigned long)addr < VMALLOC_START) ||
-			((unsigned long)addr >= VMALLOC_END ))) {
+	if (!is_vmalloc_addr(addr)) {
 		kfree(addr);
 		/* free_page((unsigned long)addr); */
 		return;

fs/proc/kcore.c

···
 		if (m == NULL) {
 			if (clear_user(buffer, tsz))
 				return -EFAULT;
-		} else if ((start >= VMALLOC_START) && (start < VMALLOC_END)) {
+		} else if (is_vmalloc_addr((void *)start)) {
 			char * elf_buf;
 			struct vm_struct *m;
 			unsigned long curstart = start;

fs/xfs/linux-2.6/kmem.c

···
 void
 kmem_free(void *ptr, size_t size)
 {
-	if (((unsigned long)ptr < VMALLOC_START) ||
-	    ((unsigned long)ptr >= VMALLOC_END)) {
+	if (!is_vmalloc_addr(ptr)) {
 		kfree(ptr);
 	} else {
 		vfree(ptr);

fs/xfs/linux-2.6/xfs_buf.c

···
 mem_to_page(
 	void			*addr)
 {
-	if (((unsigned long)addr < VMALLOC_START) ||
-	    ((unsigned long)addr >= VMALLOC_END)) {
+	if ((!is_vmalloc_addr(addr))) {
 		return virt_to_page(addr);
 	} else {
 		return vmalloc_to_page(addr);

include/linux/mm.h

···
 struct page *vmalloc_to_page(const void *addr);
 unsigned long vmalloc_to_pfn(const void *addr);
 
+/* Determine if an address is within the vmalloc range */
+static inline int is_vmalloc_addr(const void *x)
+{
+	unsigned long addr = (unsigned long)x;
+
+	return addr >= VMALLOC_START && addr < VMALLOC_END;
+}
+
 static inline struct page *compound_head(struct page *page)
 {
 	if (unlikely(PageTail(page)))

mm/sparse.c

···
 	return __kmalloc_section_memmap(nr_pages);
 }
 
-static int vaddr_in_vmalloc_area(void *addr)
-{
-	if (addr >= (void *)VMALLOC_START &&
-	    addr < (void *)VMALLOC_END)
-		return 1;
-	return 0;
-}
-
 static void __kfree_section_memmap(struct page *memmap, unsigned long nr_pages)
 {
-	if (vaddr_in_vmalloc_area(memmap))
+	if (is_vmalloc_addr(memmap))
 		vfree(memmap);
 	else
 		free_pages((unsigned long)memmap,