On Fri, 17 Jul 2015 01:14:05 +0200 Oleg Nesterov <[email protected]> wrote:
> 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.
>
> ..
>
> --- 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)
> {
So if anyone starts testing aio on NOMMU, this patch will make the
whole thing immediately go BUG. This isn't helpful :(
Yes, making AIO depend on MMU sounds better. Because if it wasn't
busted before, it sure is now!
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