[PATCH 0/4] mm: percpu: Cleanup percpu first chunk function

[Kefeng Wang]

When support page mapping percpu first chunk allocator on arm64, we
found there are lots of duplicated codes in percpu embed/page first
chunk allocator. This patchset is aimed to cleanup them and should
no function change. 

The currently supported status about 'embed' and 'page' in Archs shows
below,

embed: NEED_PER_CPU_PAGE_FIRST_CHUNK
page:  NEED_PER_CPU_EMBED_FIRST_CHUNK

	embed	page
------------------------
arm64	  Y	 Y
mips	  Y	 N
powerpc	  Y	 Y
riscv	  Y	 N
sparc	  Y	 Y
x86	  Y	 Y
------------------------

There are two interfaces about percpu first chunk allocator,

 extern int __init pcpu_embed_first_chunk(size_t reserved_size, size_t dyn_size,
                                size_t atom_size,
                                pcpu_fc_cpu_distance_fn_t cpu_distance_fn,
-                               pcpu_fc_alloc_fn_t alloc_fn,
-                               pcpu_fc_free_fn_t free_fn);
+                               pcpu_fc_cpu_to_node_fn_t cpu_to_nd_fn);


 extern int __init pcpu_page_first_chunk(size_t reserved_size,
-                               pcpu_fc_alloc_fn_t alloc_fn,
-                               pcpu_fc_free_fn_t free_fn,
-                               pcpu_fc_populate_pte_fn_t populate_pte_fn);
+                               pcpu_fc_cpu_to_node_fn_t cpu_to_nd_fn);


The pcpu_fc_alloc_fn_t/pcpu_fc_free_fn_t is killed, we provide generic
pcpu_fc_alloc() and pcpu_fc_free() function, which are called in the
pcpu_embed/page_first_chunk().

1) For pcpu_embed_first_chunk(), pcpu_fc_cpu_to_node_fn_t is needed to be
   provided when archs supported NUMA.
2) For pcpu_page_first_chunk(), the pcpu_fc_populate_pte_fn_t is killed too,
   a generic pcpu_populate_pte() which marked '__weak' is provided, if you
   need a different function to populate pte on the arch(like x86), please
   provide its own implementation.

I have been built test on arm64/ia64/mips/powerpc/sparcx86/riscv based
on v5.16-rc4 on my machine, also all patches are in[1], which checked
by lkp too,
  [kevin78:percpu-cleanup] BUILD SUCCESS c14a59a0aad7db88ebddbeb5e914ddcccb406e1c.

[1] https://github.com/kevin78/linux.git percpu-cleanup

Changes since RFC
- Address Dennis's comments 

RFC:
https://lore.kernel.org/linux-mm/4fecd1ac-6c0a-f0fa-1ffb-18f3f266809d@xxxxxxxxxx/T/

Kefeng Wang (4):
  mm: percpu: Generalize percpu related config
  mm: percpu: Add pcpu_fc_cpu_to_node_fn_t typedef
  mm: percpu: Add generic pcpu_fc_alloc/free funciton
  mm: percpu: Add generic pcpu_populate_pte() function

 arch/arm64/Kconfig             |  20 +----
 arch/ia64/Kconfig              |   9 +-
 arch/mips/Kconfig              |  10 +--
 arch/mips/mm/init.c            |  14 +--
 arch/powerpc/Kconfig           |  17 +---
 arch/powerpc/kernel/setup_64.c |  97 ++-------------------
 arch/riscv/Kconfig             |  10 +--
 arch/sparc/Kconfig             |  12 +--
 arch/sparc/kernel/smp_64.c     | 103 +---------------------
 arch/x86/Kconfig               |  17 +---
 arch/x86/kernel/setup_percpu.c |  66 ++------------
 drivers/base/arch_numa.c       |  68 +--------------
 include/linux/percpu.h         |  13 +--
 mm/Kconfig                     |  12 +++
 mm/percpu.c                    | 154 +++++++++++++++++++++++++--------
 15 files changed, 180 insertions(+), 442 deletions(-)

-- 
2.18.0.huawei.25