Dear Mantainers,

I find there is an inevitable problem for linux-5.x ARM64 kdump that the error "page excluded: kernel virtual address: xxx" will be occured when read the address of ext4_super_block for ext4 filesystem in latest crash utility debugging enviroment.

1) Here's my reproduce steps:

crash64> mount

     MOUNT           SUPERBLK     TYPE   DEVNAME   DIRNAME
ffff000001e65180 ffff000001c1c000 rootfs none      /
ffff00002ea66000 ffff00000288e000 ext4   /dev/root /
crash64> struct super_block.s_fs_info -x ffff00000288e000
  s_fs_info = 0xffff000002885000,
crash64> struct ext4_sb_info.s_es -x 0xffff000002885000
  s_es = 0xffff0000043c2400,
crash64> struct ext4_sb_info.s_es -x 0xffff0000043c2400
struct: page excluded: kernel virtual address: ffff0000043c2400  type: "gdb_readmem_callback"
crash64> rd 0xffff0000043c2400
rd: page excluded: kernel virtual address: ffff0000043c2400  type: "64-bit KVADDR"
crash64> kmem -p 0xffff0000043c2400
      PAGE       PHYSICAL      MAPPING       INDEX CNT FLAGS
fffffc000010f080 443c2000 ffff000002f93af0        0  2 ffff00000022036 referenced,uptodate,lru,active,private,mappedtodisk
crash64> vtop 0xffff0000043c2400
VIRTUAL           PHYSICAL
ffff0000043c2400  443c2400

PAGE DIRECTORY: ffff80001163b000
   PGD: ffff80001163b000 => 180000007fff9803
   PUD: ffff00003fff9000 => 180000007fff8803
   PMD: ffff00003fff8108 => 180000007ffe0803
   PTE: ffff00003ffe0e10 => 680000443c2f07
  PAGE: 443c2000

     PTE        PHYSICAL  FLAGS
680000443c2f07  443c2000  (VALID|SHARED|AF|NG|PXN|UXN)

      PAGE       PHYSICAL      MAPPING       INDEX CNT FLAGS
fffffc000010f080 443c2000 ffff000002f93af0        0  2 ffff00000022036 referenced,uptodate,lru,active,private,mappedtodisk


2) Here's the kernel virtual kernel memory layout for my tested arm64 kernel version 5.15, we can see 0xffff0000043c2400 is in the kernel linear memory region :

[    0.000000] Virtual kernel memory layout:
[    0.000000]     modules : 0xffff800008000000 - 0xffff800010000000   (   128 MB)
[    0.000000]     vmalloc : 0xffff800010000000 - 0xfffffbfff0000000   (126975 GB)
[    0.000000]       .text : 0xffff800010000000 - 0xffff8000111a0000   ( 18048 KB)
[    0.000000]       .init : 0xffff800011640000 - 0xffff800011760000   (  1152 KB)
[    0.000000]     .rodata : 0xffff8000111a0000 - 0xffff800011636000   (  4696 KB)
[    0.000000]       .data : 0xffff800011760000 - 0xffff800011902200   (  1673 KB)
[    0.000000]        .bss : 0xffff800011902200 - 0xffff8000119c6fb0   (   788 KB)
[    0.000000]     fixed   : 0xfffffbfffdbf9000 - 0xfffffbfffe000000   (  4124 KB)
[    0.000000]     PCI I/O : 0xfffffbfffe800000 - 0xfffffbffff800000   (    16 MB)
[    0.000000]     vmemmap : 0xfffffc0000000000 - 0xfffffe0000000000   (  2048 GB maximum)
[    0.000000]               0xfffffc0000000000 - 0xfffffc0001000000   (    16 MB actual)
[    0.000000]     memory  : 0xffff000000000000 - 0xffff000040000000   (  1024 MB)
[    0.000000]     PAGE_OFFSET  : 0xffff000000000000
[    0.000000]     KIMAGE_VADDR  : 0xffff800010000000
[    0.000000]     kimage_voffset : 0xffff7fffcfe00000
[    0.000000]     PHYS_OFFSET  : 0x40000000
[    0.000000]     start memory  : 0x40000000


I have no idea whether this problem is something wrong with crash utility. Could anybody please help this?

Thanks