Subject: [PATCH] mm-move-mremap-from-file_operations-to-vm_operations_struct-fix

From: Oleg Nesterov <[email-masked]>
Date: Fri, 17 Jul 2015 01:14:05 +0200

fs/aio.c can't be compiled if CONFIG_MMU=n, filemap_page_mkwrite()
is not defined in this case. Add yet another "must not be called"
helper into nommu.c to make the linker happy.

I still think this is pointless, afaics sys_io_setup() simply can't
succeed if CONFIG_MMU=n. Instead we should make CONFIG_AIO depend
on CONFIG_MMU.

Reported-by: Fengguang Wu <[email-masked]>
Reported-by: Stephen Rothwell <[email-masked]>
Signed-off-by: Oleg Nesterov <[email-masked]>
---
 mm/nommu.c |    6 ++++++
 1 files changed, 6 insertions(+), 0 deletions(-)

diff --git a/mm/nommu.c b/mm/nommu.c
index e3026fd..979afad 100644
--- a/mm/nommu.c
+++ b/mm/nommu.c
@@ -2008,6 +2008,12 @@ void filemap_map_pages(struct vm_area_struct *vma, struct vm_fault *vmf)
 }
 EXPORT_SYMBOL(filemap_map_pages);
 
+int filemap_page_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf)
+{
+	BUG();
+	return 0;
+}
+
 static int __access_remote_vm(struct task_struct *tsk, struct mm_struct *mm,
 		unsigned long addr, void *buf, int len, int write)
 {
-- 
1.5.5.1