Hi Randy,

On Sun, Sep 06, 2020 at 12:33:08PM -0700, Randy Dunlap wrote:
> From: Randy Dunlap <rdun...@infradead.org>
> 
> Fix build errors in Microblaze when CONFIG_MEMORY_ISOLATION is not
> set/enabled by adding stubs for 3 missing functions.

I've tried to follow Kconfig dependencies to see how could we have both
CONTIG_ALLOC=y and CONFIG_MEMORY_ISOLATION=n and I could not find how
was this possible.

We have 

config CONTIG_ALLOC
        def_bool (MEMORY_ISOLATION && COMPACTION) || CMA

and

config CMA
        bool "Contiguous Memory Allocator"
        depends on MMU
        select MIGRATION
        select MEMORY_ISOLATION

and alloc_contig_range() is hidden behind '#ifdef CONFIG_CONTIG_ALLOC'

In any rate, I think the better fix would be to update Kconfig
dependencies rather than add stubs for these functions.

> Fixes these build errors:
> 
> gcc-9.3.0-nolibc/microblaze-linux/bin/microblaze-linux-ld: mm/page_alloc.o: 
> in function `alloc_contig_range':
> (.text+0xa0c0): undefined reference to `start_isolate_page_range'
> gcc-9.3.0-nolibc/microblaze-linux/bin/microblaze-linux-ld: (.text+0xa2bc): 
> undefined reference to `test_pages_isolated'
> gcc-9.3.0-nolibc/microblaze-linux/bin/microblaze-linux-ld: (.text+0xa378): 
> undefined reference to `undo_isolate_page_range'
> 
> Fixes: 0815f3d81d76 ("mm: page_isolation: MIGRATE_CMA isolation functions 
> added") # v3.10
> Fixes: b023f46813cd ("memory-hotplug: skip HWPoisoned page when offlining 
> pages") # v3.10
> Reported-by: kernel test robot <l...@intel.com>
> Signed-off-by: Randy Dunlap <rdun...@infradead.org>
> Cc: Michal Nazarewicz <min...@mina86.com>
> Cc: Wen Congyang <we...@cn.fujitsu.com>
> Cc: Michal Simek <mon...@monstr.eu>
> Cc: Christoph Hellwig <h...@lst.de>
> Cc: Andrew Morton <a...@linux-foundation.org>
> Cc: Mike Rapoport <r...@linux.ibm.com>
> Cc: linux...@kvack.org
> ---
>  include/linux/page-isolation.h |   16 ++++++++++++++++
>  1 file changed, 16 insertions(+)
> 
> --- linux-next-20200903.orig/include/linux/page-isolation.h
> +++ linux-next-20200903/include/linux/page-isolation.h
> @@ -28,6 +28,22 @@ static inline bool is_migrate_isolate(in
>  {
>       return false;
>  }
> +static inline int test_pages_isolated(unsigned long start_pfn,
> +                                   unsigned long end_pfn, int isol_flags)
> +{
> +     return 0;
> +}
> +static inline int
> +start_isolate_page_range(unsigned long start_pfn, unsigned long end_pfn,
> +                      unsigned migratetype, int flags)
> +{
> +     return 0;
> +}
> +static inline void
> +undo_isolate_page_range(unsigned long start_pfn, unsigned long end_pfn,
> +                     unsigned migratetype)
> +{
> +}
>  #endif
>  
>  #define MEMORY_OFFLINE       0x1
> 
> 

-- 
Sincerely yours,
Mike.

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