[kernel-debug] Kdump kernel panic's at memblock_alloc_try_nid() or kasan_populate_pmd() function.

Issue

• Kdump kernel is immediately getting panic during testing in kernel-debug environment.
• it is reproducible if the crashkernel reservation set to below 768M.
• Nothing is showing on the console or serial console after issuing the sysrq to the system.
• Found below panic message by adding earlyprint=ttyS0 to the kernel command line.

KASLR disabled: 'nokaslr' on cmdline.
[    0.000000] Linux version 4.18.0-348.7.1.el8_5.x86_64+debug (mockbuild@x86-vm-08.build.eng.bos.redhat.com) (gcc version 8.5.0 20210514 (Red Hat 8.5.0-4) (GCC)) #1 SMP Wed Dec 8 21:17:08 EST 2021

[    0.000000] On node 0 totalpages: 65693
[    0.000000]   DMA zone: 3 pages used for memmap
[    0.000000]   DMA zone: 158 pages, LIFO batch:0
[    0.000000]   DMA32 zone: 1024 pages used for memmap
[    0.000000]   DMA32 zone: 65535 pages, LIFO batch:15
[    0.000000] Kernel panic - not syncing: memblock_alloc_try_nid: Failed to allocate 4096 bytes align=0x1000 nid=0 from=0x1000000 max_addr=0x0 <<----
[    0.000000] CPU: 0 PID: 0 Comm: swapper Not tainted 4.18.0-348.7.1.el8_5.x86_64+debug #1
[    0.000000] Hardware name: Red Hat KVM/RHEL-AV, BIOS 1.13.0-2.module+el8.3.0+7353+9de0a3cc 04/01/2014
[    0.000000] Call Trace:
[    0.000000]  ? dump_stack+0x8e/0xd0
[    0.000000]  ? panic+0x1cc/0x3f3
[    0.000000]  ? __warn_printk+0xdb/0xdb
[    0.000000]  ? memblock_alloc_internal+0x163/0x22a
[    0.000000]  ? memblock_alloc_range+0x11/0x11
[    0.000000]  ? kasan_report+0x20/0x50
[    0.000000]  ? memblock_alloc_try_nid+0x87/0x9d
[    0.000000]  ? kasan_populate_pgd+0x6a0/0x7ed
[    0.000000]  ? kasan_populate_shadow+0xe4/0xf9
[    0.000000]  ? kasan_init+0x47e/0x644
[    0.000000]  ? setup_arch+0x1593/0x1a05
[    0.000000]  ? reserve_standard_io_resources+0x49/0x49
[    0.000000]  ? vprintk_emit+0x164/0x490
[    0.000000]  ? printk+0x9f/0xc5
[    0.000000]  ? kmsg_dump_rewind_nolock+0xd9/0xd9
[    0.000000]  ? cgroup_init_early+0x2ce/0x474
[    0.000000]  ? start_kernel+0xc6/0x7ba
[    0.000000]  ? thread_stack_cache_init+0x6/0x6
[    0.000000]  ? x86_family+0x5/0x20
[    0.000000]  ? load_ucode_bsp+0x49/0x22b
[    0.000000]  ? secondary_startup_64_no_verify+0xc2/0xcb
[    0.000000] ---[ end Kernel panic - not syncing: memblock_alloc_try_nid: Failed to allocate 4096 bytes align=0x1000 nid=0 from=0x1000000 max_addr=0x0
[    0.000000]  ]---
PANIC: early exception 0x0d IP 10:ffffffff81220e96 error 7eb cr2 0xffff88807e001000
PANIC: early exception 0x0d IP 10:ffffffff819efe5c error 0 cr2 0xffff88807e001000

• In another instance.

[    0.213768] Kernel panic - not syncing: kasan_populate_pmd+0x137/0x208: Failed to allocate page, nid=0 from=1000000
[    0.218179] CPU: 0 PID: 0 Comm: swapper Not tainted 5.14.0-39.el9.x86_64+debug #1
[    0.220125] Hardware name: Red Hat KVM/RHEL-AV, BIOS 0.0.0 02/06/2015
[    0.221799] Call Trace:
[    0.222482]  ? dump_stack_lvl+0x57/0x7d
[    0.223507]  ? panic+0x216/0x4c9
[    0.224352]  ? __warn_printk+0xf3/0xf3
[    0.225338]  ? memblock_alloc_try_nid_raw+0x102/0x102
[    0.226661]  ? pud_set_huge+0x2b0/0x2b0
[    0.227671]  ? kasan_populate_pmd+0x137/0x208
[    0.228821]  ? early_alloc+0x95/0x99
[    0.229759]  ? kasan_populate_pmd+0x137/0x208
[    0.230906]  ? kasan_populate_pud+0x16f/0x188
[    0.232054]  ? kasan_populate_shadow+0x1a9/0x1fb
[    0.233278]  ? kasan_init+0x49d/0x5f5
[    0.234253]  ? setup_arch+0x1013/0x13c4
[    0.235270]  ? start_kernel+0x74/0x3eb
[    0.236263]  ? secondary_startup_64_no_verify+0xc2/0xcb
[    0.237735] ---[ end Kernel panic - not syncing: kasan_populate_pmd+0x137/0x208: Failed to allocate page, nid=0 from=1000000 ]---
PANIC: early exception 0x0d IP 10:ffffffff8305b697 error 763 cr2 0xffff88807adff000