Hi Will and Catalin，any comments，kindly ping, thanks.

On 2021/7/20 10:51, Kefeng Wang wrote:

Percpu embedded first chunk allocator is the firstly option, but it
could fails on ARM64, eg,
   "percpu: max_distance=0x5fcfdc640000 too large for vmalloc space 0x781fefff0000"
   "percpu: max_distance=0x600000540000 too large for vmalloc space 0x7dffb7ff0000"
   "percpu: max_distance=0x5fff9adb0000 too large for vmalloc space 0x5dffb7ff0000"

then we could meet "WARNING: CPU: 15 PID: 461 at vmalloc.c:3087 pcpu_get_vm_areas+0x488/0x838",
even the system could not boot successfully.

Let's implement page mapping percpu first chunk allocator as a fallback
to the embedding allocator to increase the robustness of the system.

Also fix a crash when both NEED_PER_CPU_PAGE_FIRST_CHUNK and KASAN_VMALLOC enabled.

Tested on ARM64 qemu with cmdline "percpu_alloc=page" based on v5.14-rc2.

V2:
- fix build error when CONFIG_KASAN disabled, found by lkp@intel.com
- drop wrong __weak comment from kasan_populate_early_vm_area_shadow(),
   found by Marco Elver [off-list ref]

Kefeng Wang (3):
   vmalloc: Choose a better start address in vm_area_register_early()
   arm64: Support page mapping percpu first chunk allocator
   kasan: arm64: Fix pcpu_page_first_chunk crash with KASAN_VMALLOC

  arch/arm64/Kconfig         |  4 ++
  arch/arm64/mm/kasan_init.c | 17 ++++++++
  drivers/base/arch_numa.c   | 82 +++++++++++++++++++++++++++++++++-----
  include/linux/kasan.h      |  6 +++
  mm/kasan/init.c            |  5 +++
  mm/vmalloc.c               |  9 +++--
  6 files changed, 110 insertions(+), 13 deletions(-)

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