[PATCH] <linux/page-isolation.h>: provide stubs for MEMORY_ISOLATION not set (for Microblaze)

[Randy Dunlap]

From: Randy Dunlap <rdunlap@xxxxxxxxxxxxx>

Fix build errors in Microblaze when CONFIG_MEMORY_ISOLATION is not
set/enabled by adding stubs for 3 missing 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 <lkp@xxxxxxxxx>
Signed-off-by: Randy Dunlap <rdunlap@xxxxxxxxxxxxx>
Cc: Michal Nazarewicz <mina86@xxxxxxxxxx>
Cc: Wen Congyang <wency@xxxxxxxxxxxxxx>
Cc: Michal Simek <monstr@xxxxxxxxx>
Cc: Christoph Hellwig <hch@xxxxxx>
Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Cc: Mike Rapoport <rppt@xxxxxxxxxxxxx>
Cc: linux-mm@xxxxxxxxx
---
 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