[PATCH AUTOSEL 5.3 42/49] mm: add dummy can_do_mlock() helper

[Sasha Levin]

From: Arnd Bergmann <arnd@xxxxxxxx>

[ Upstream commit 710ec38b0f633ab3e2581f07a73442d809e28ab0 ]

On kernels without CONFIG_MMU, we get a link error for the siw driver:

drivers/infiniband/sw/siw/siw_mem.o: In function `siw_umem_get':
siw_mem.c:(.text+0x4c8): undefined reference to `can_do_mlock'

This is probably not the only driver that needs the function and could
otherwise build correctly without CONFIG_MMU, so add a dummy variant that
always returns false.

Link: http://lkml.kernel.org/r/20190909204201.931830-1-arnd@xxxxxxxx
Fixes: 2251334dcac9 ("rdma/siw: application buffer management")
Signed-off-by: Arnd Bergmann <arnd@xxxxxxxx>
Suggested-by: Jason Gunthorpe <jgg@xxxxxxxxxxxx>
Acked-by: Michal Hocko <mhocko@xxxxxxxx>
Cc: Bernard Metzler <bmt@xxxxxxxxxxxxxx>
Cc: "Matthew Wilcox (Oracle)" <willy@xxxxxxxxxxxxx>
Cc: "Kirill A. Shutemov" <kirill.shutemov@xxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
 include/linux/mm.h | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/include/linux/mm.h b/include/linux/mm.h
index 0334ca97c584d..fe4552e1c40b4 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -1405,7 +1405,11 @@ extern void pagefault_out_of_memory(void);
 
 extern void show_free_areas(unsigned int flags, nodemask_t *nodemask);
 
+#ifdef CONFIG_MMU
 extern bool can_do_mlock(void);
+#else
+static inline bool can_do_mlock(void) { return false; }
+#endif
 extern int user_shm_lock(size_t, struct user_struct *);
 extern void user_shm_unlock(size_t, struct user_struct *);
 
-- 
2.20.1