crash load 5.12 before vmcore, parse section_size_bits equals 27,
but it should be equals 30. because defined "CONFIG_ARM64_4K_PAGES",
The commit "568c6f04" for compat android gki, so we should cleanup.

Exp:
Before:
crash vmcore vmlinux -d1
...
xtime timespec.tv_sec: 603549d0: Wed Feb 24 02:30:40 CST 2021
utsname:
     sysname: Linux
    nodename: localhost
     release: 4.14.180-perf-g4483caa8ae80-dirty
     version: #1 SMP PREEMPT Wed Feb 24 03:16:01 CST 2021
     machine: aarch64
  domainname: localdomain
...
SECTION_SIZE_BITS: 27
...

After:
crash vmcore vmlinux -d1
...
xtime timespec.tv_sec: 603549d0: Wed Feb 24 02:30:40 CST 2021
utsname:
     sysname: Linux
    nodename: localhost
     release: 4.14.180-perf-g4483caa8ae80-dirty
     version: #1 SMP PREEMPT Wed Feb 24 03:16:01 CST 2021
     machine: aarch64
  domainname: localdomain
...
SECTION_SIZE_BITS: 30
...

diff --git a/arm64.c b/arm64.c
index 06e7451..05ffdb3 100644
--- a/arm64.c
+++ b/arm64.c
@@ -1698,14 +1698,7 @@ arm64_get_section_size_bits(void)
                if ((ret = get_kernel_config("CONFIG_MEMORY_HOTPLUG", NULL)) == IKCONFIG_Y) {
                        if ((ret = get_kernel_config("CONFIG_HOTPLUG_SIZE_BITS", &string)) == IKCONFIG_STR)
                                machdep->section_size_bits = atol(string);
-               }
-
-               /* arm64: reduce section size for sparsemem */
-               if ((ret = get_kernel_config("CONFIG_ARM64_4K_PAGES", NULL)) == IKCONFIG_Y
-                       || (ret = get_kernel_config("CONFIG_ARM64_16K_PAGES", NULL)) == IKCONFIG_Y)
-                       machdep->section_size_bits = _SECTION_SIZE_BITS_5_12;
-               else if ((ret = get_kernel_config("CONFIG_ARM64_64K_PAGES", NULL)) == IKCONFIG_Y)
-                       machdep->section_size_bits = _SECTION_SIZE_BITS_5_12_64K;
+               }
        }
 
        if (CRASHDEBUG(1))

Thanks,

Guanyou.