arch, mm: introduce arch_mm_preinit

Currently, implementation of mem_init() in every architecture consists of
one or more of the following:

* initializations that must run before page allocator is active, for
  instance swiotlb_init()
* a call to memblock_free_all() to release all the memory to the buddy
  allocator
* initializations that must run after page allocator is ready and there is
  no arch-specific hook other than mem_init() for that, like for example
  register_page_bootmem_info() in x86 and sparc64 or simple setting of
  mem_init_done = 1 in several architectures
* a bunch of semi-related stuff that apparently had no better place to
  live, for example a ton of BUILD_BUG_ON()s in parisc.

Introduce arch_mm_preinit() that will be the first thing called from
mm_core_init(). On architectures that have initializations that must happen
before the page allocator is ready, move those into arch_mm_preinit() along
with the code that does not depend on ordering with page allocator setup.

On several architectures this results in reduction of mem_init() to a
single call to memblock_free_all() that allows its consolidation next.

Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Mike Rapoport (Microsoft) <[email protected]>
Acked-by: Dave Hansen <[email protected]>	[x86]
Tested-by: Mark Brown <[email protected]>
Cc: Alexander Gordeev <[email protected]>
Cc: Andreas Larsson <[email protected]>
Cc: Andy Lutomirski <[email protected]>
Cc: Ard Biesheuvel <[email protected]>
Cc: Arnd Bergmann <[email protected]>
Cc: Borislav Betkov <[email protected]>
Cc: Catalin Marinas <[email protected]>
Cc: David S. Miller <[email protected]>
Cc: Dinh Nguyen <[email protected]>
Cc: Geert Uytterhoeven <[email protected]>
Cc: Gerald Schaefer <[email protected]>
Cc: Guo Ren (csky) <[email protected]>
Cc: Heiko Carstens <[email protected]>
Cc: Helge Deller <[email protected]>
Cc: Huacai Chen <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: Jiaxun Yang <[email protected]>
Cc: Johannes Berg <[email protected]>
Cc: John Paul Adrian Glaubitz <[email protected]>
Cc: Madhavan Srinivasan <[email protected]>
Cc: Matt Turner <[email protected]>
Cc: Max Filippov <[email protected]>
Cc: Michael Ellerman <[email protected]>
Cc: Michal Simek <[email protected]>
Cc: Palmer Dabbelt <[email protected]>
Cc: Richard Weinberger <[email protected]>
Cc: Russel King <[email protected]>
Cc: Stafford Horne <[email protected]>
Cc: Thomas Bogendoerfer <[email protected]>
Cc: Thomas Gleinxer <[email protected]>
Cc: Vasily Gorbik <[email protected]>
Cc: Vineet Gupta <[email protected]>
Cc: Will Deacon <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

1 files changed, 5 insertions, 0 deletions

diff --git a/mm/mm_init.c b/mm/mm_init.c
index bd7071c32a44..6844de516a50 100644
--- a/mm/mm_init.c
+++ b/mm/mm_init.c
@@ -2734,11 +2734,16 @@ static void __init mem_init_print_info(void)
 		);
 }
 
+void __init __weak arch_mm_preinit(void)
+{
+}
+
 /*
  * Set up kernel memory allocators
  */
 void __init mm_core_init(void)
 {
+	arch_mm_preinit();
 	hugetlb_bootmem_alloc();
 
 	/* Initializations relying on SMP setup */