Re: [mmotm:master 140/321] fs/built-in.o:undefined reference to `filemap_page_mkwrite'

[Oleg Nesterov <oleg@redhat.com>]

Thanks!

On 07/16, kbuild test robot wrote:
>
> tree:   git://git.cmpxchg.org/linux-mmotm.git master
> head:   6102e3c755ac0084fdce65f69a7a149fc51a8a86
> commit: db5e4748f77b7cefa37e61324cc440f8670213c2 [140/321] mm: move ->mremap() from file_operations to vm_operations_struct
> config: sh-rsk7269_defconfig (attached as .config)
> reproduce:
>   wget https://git.kernel.org/cgit/linux/kernel/git/wfg/lkp-tests.git/plain/sbin/make.cross -O ~/bin/make.cross
>   chmod +x ~/bin/make.cross
>   git checkout db5e4748f77b7cefa37e61324cc440f8670213c2
>   # save the attached .config to linux build tree
>   make.cross ARCH=sh

doesn't work for me...

> All error/warnings (new ones prefixed by >>):
>
> >> fs/built-in.o:(.rodata+0x1090): undefined reference to `filemap_page_mkwrite'

but the problem looks clear: CONFIG_MMU is not set, so we need
a dummy filemap_page_mkwrite() along with generic_file_mmap() and
generic_file_readonly_mmap().

I'll send the fix, but...

Benjamin, Jeff, shouldn't AIO depend on MMU? Or it can actually work even
if CONFIG_MMU=n?

Oleg.

--- a/init/Kconfig
+++ b/init/Kconfig
@@ -1558,6 +1558,7 @@ config SHMEM
 
 config AIO
 	bool "Enable AIO support" if EXPERT
+	depends on MMU
 	default y
 	help
 	  This option enables POSIX asynchronous I/O which may by used

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