When build with !CONFIG_MMU, the variable 'vmcore_mmap_ops'
is defined but not used:

>> fs/proc/vmcore.c:458:42: warning: unused variable 'vmcore_mmap_ops'
     458 | static const struct vm_operations_struct vmcore_mmap_ops = {

Fix this by only defining it when CONFIG_MMU is enabled.

Fixes: 9cb218131de1 ("vmcore: introduce remap_oldmem_pfn_range()")
Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/lkml/202410301936.GcE8yUos-lkp@intel.com/
Signed-off-by: Qi Xi <xiqi2@huawei.com>
---
v3: move changelogs after the '---' line
v2: use ifdef instead of __maybe_unused

 fs/proc/vmcore.c | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/fs/proc/vmcore.c b/fs/proc/vmcore.c
index 1fb213f379a5..9ed1f6902c8f 100644
--- a/fs/proc/vmcore.c
+++ b/fs/proc/vmcore.c
@@ -455,10 +455,6 @@ static vm_fault_t mmap_vmcore_fault(struct vm_fault *vmf)
 #endif
 }
 
-static const struct vm_operations_struct vmcore_mmap_ops = {
-	.fault = mmap_vmcore_fault,
-};
-
 /**
  * vmcore_alloc_buf - allocate buffer in vmalloc memory
  * @size: size of buffer
@@ -486,6 +482,11 @@ static inline char *vmcore_alloc_buf(size_t size)
  * virtually contiguous user-space in ELF layout.
  */
 #ifdef CONFIG_MMU
+
+static const struct vm_operations_struct vmcore_mmap_ops = {
+	.fault = mmap_vmcore_fault,
+};
+
 /*
  * remap_oldmem_pfn_checked - do remap_oldmem_pfn_range replacing all pages
  * reported as not being ram with the zero page.
-- 
2.33.0