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