fs/proc/vmcore.c: fix warning when CONFIG_MMU=n

>> fs/proc/vmcore.c:424:19: warning: 'mmap_vmcore_fault' defined but not used [-Wunused-function]
     424 | static vm_fault_t mmap_vmcore_fault(struct vm_fault *vmf)

Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202411140156.2o0nS4fl-lkp@intel.com/
Cc: Qi Xi <xiqi2@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

Author: akpm00

fs/proc/vmcore.c

@@ -414,6 +414,34 @@ static ssize_t read_vmcore(struct kiocb *iocb, struct iov_iter *iter)
 	return __read_vmcore(iter, &iocb->ki_pos);
 }
 
+/**
+ * vmcore_alloc_buf - allocate buffer in vmalloc memory
+ * @size: size of buffer
+ *
+ * If CONFIG_MMU is defined, use vmalloc_user() to allow users to mmap
+ * the buffer to user-space by means of remap_vmalloc_range().
+ *
+ * If CONFIG_MMU is not defined, use vzalloc() since mmap_vmcore() is
+ * disabled and there's no need to allow users to mmap the buffer.
+ */
+static inline char *vmcore_alloc_buf(size_t size)
+{
+#ifdef CONFIG_MMU
+	return vmalloc_user(size);
+#else
+	return vzalloc(size);
+#endif
+}
+
+/*
+ * Disable mmap_vmcore() if CONFIG_MMU is not defined. MMU is
+ * essential for mmap_vmcore() in order to map physically
+ * non-contiguous objects (ELF header, ELF note segment and memory
+ * regions in the 1st kernel pointed to by PT_LOAD entries) into
+ * virtually contiguous user-space in ELF layout.
+ */
+#ifdef CONFIG_MMU
+
 /*
  * The vmcore fault handler uses the page cache and fills data using the
  * standard __read_vmcore() function.
@@ -457,34 +485,6 @@ static vm_fault_t mmap_vmcore_fault(struct vm_fault *vmf)
 #endif
 }
 
-/**
- * vmcore_alloc_buf - allocate buffer in vmalloc memory
- * @size: size of buffer
- *
- * If CONFIG_MMU is defined, use vmalloc_user() to allow users to mmap
- * the buffer to user-space by means of remap_vmalloc_range().
- *
- * If CONFIG_MMU is not defined, use vzalloc() since mmap_vmcore() is
- * disabled and there's no need to allow users to mmap the buffer.
- */
-static inline char *vmcore_alloc_buf(size_t size)
-{
-#ifdef CONFIG_MMU
-	return vmalloc_user(size);
-#else
-	return vzalloc(size);
-#endif
-}
-
-/*
- * Disable mmap_vmcore() if CONFIG_MMU is not defined. MMU is
- * essential for mmap_vmcore() in order to map physically
- * non-contiguous objects (ELF header, ELF note segment and memory
- * regions in the 1st kernel pointed to by PT_LOAD entries) into
- * virtually contiguous user-space in ELF layout.
- */
-#ifdef CONFIG_MMU
-
 static const struct vm_operations_struct vmcore_mmap_ops = {
 	.fault = mmap_vmcore_fault,
 };