3、log 命令可以打印系统消息缓冲区，从而可能找到系统崩溃的线索。输出太多，这里只截取部分信息。
crash> log [ 0.000000] Initializing cgroup subsys cpuset [ 0.000000] Initializing cgroup subsys cpu [ 0.000000] Initializing cgroup subsys cpuacct [ 0.000000] Linux version 3.10.0-1160.15.2.el7.x86_64 (mockbuild@kbuilder.bsys.centos.org) (gcc version 4.8.5 20150623 (Red Hat 4.8.5-44) (GCC) ) #1 SMP Wed Feb 3 15:06:38 UTC 2021 [ 0.000000] Command line: BOOT_IMAGE=http://www.likecs.com/boot/vmlinuz-3.10.0-1160.15.2.el7.x86_64 root=UUID=1114fe9e-2309-4580-b183-d778e6d97397 ro crashkernel=auto rhgb quiet LANG=en_US.UTF-8 idle=halt biosdevname=0 net.ifnames=0 console=tty0 console=ttyS0,115200n8 noibrs [ 0.000000] e820: BIOS-provided physical RAM map: [ 0.000000] BIOS-e820: [mem 0x0000000000000000-0x000000000009fbff] usable [ 0.000000] BIOS-e820: [mem 0x000000000009fc00-0x000000000009ffff] reserved [ 0.000000] BIOS-e820: [mem 0x00000000000f0000-0x00000000000fffff] reserved [ 0.000000] BIOS-e820: [mem 0x0000000000100000-0x0000000013ffffff] usable [ 0.000000] BIOS-e820: [mem 0x0000000014000000-0x000000001511ffff] reserved [ 0.000000] BIOS-e820: [mem 0x0000000015120000-0x00000000bffcdfff] usable [ 0.000000] BIOS-e820: [mem 0x00000000bffce000-0x00000000bfffffff] reserved [ 0.000000] BIOS-e820: [mem 0x00000000feffc000-0x00000000feffffff] reserved [ 0.000000] BIOS-e820: [mem 0x00000000fffc0000-0x00000000ffffffff] reserved [ 0.000000] BIOS-e820: [mem 0x0000000100000000-0x0000000fffffffff] usable [ 0.000000] BIOS-e820: [mem 0x0000001000000000-0x000000103fffffff] reserved [ 0.000000] NX (Execute Disable) protection: active [ 0.000000] SMBIOS 2.8 present. [ 0.000000] DMI: Alibaba Cloud Alibaba Cloud ECS, BIOS e623647 04/01/2014 [ 0.000000] Hypervisor detected: KVM [ 0.000000] e820: update [mem 0x00000000-0x00000fff] usable ==> reserved [ 0.000000] e820: remove [mem 0x000a0000-0x000fffff] usable [ 0.000000] e820: last_pfn = 0x1000000 max_arch_pfn = 0x400000000 [ 0.000000] MTRR default type: write-back [ 0.000000] MTRR fixed ranges enabled: [ 0.000000] 00000-9FFFF write-back [ 0.000000] A0000-BFFFF uncachable [ 0.000000] C0000-FFFFF write-protect [ 0.000000] MTRR variable ranges enabled: [ 0.000000] 0 base 0000C0000000 mask 3FFFC0000000 uncachable [ 0.000000] 1 disabled [ 0.000000] 2 disabled [ 0.000000] 3 disabled [ 0.000000] 4 disabled [ 0.000000] 5 disabled [ 0.000000] 6 disabled [ 0.000000] 7 disabled [ 0.000000] PAT configuration [0-7]: WB WC UC- UC WB WP UC- UC [ 0.000000] e820: last_pfn = 0xbffce max_arch_pfn = 0x400000000 [ 0.000000] found SMP MP-table at [mem 0x000f5a00-0x000f5a0f] mapped at [ffffffffff200a00] [ 0.000000] Base memory trampoline at [ffff90f800099000] 99000 size 24576 [ 0.000000] Using GB pages for direct mapping [ 0.000000] BRK [0x70e74000, 0x70e74fff] PGTABLE [ 0.000000] BRK [0x70e75000, 0x70e75fff] PGTABLE [ 0.000000] BRK [0x70e76000, 0x70e76fff] PGTABLE [ 0.000000] BRK [0x70e77000, 0x70e77fff] PGTABLE [ 0.000000] BRK [0x70e78000, 0x70e78fff] PGTABLE [ 0.000000] RAMDISK: [mem 0x3625c000-0x37125fff] [ 0.000000] Early table checksum verification disabled [ 0.000000] ACPI: RSDP 00000000000f59b0 00014 (v00 BOCHS ) [ 0.000000] ACPI: RSDT 00000000bffe2185 00034 (v01 BOCHS BXPCRSDT 00000001 BXPC 00000001) [ 0.000000] ACPI: FACP 00000000bffe093e 00074 (v01 BOCHS BXPCFACP 00000001 BXPC 00000001) [ 0.000000] ACPI: DSDT 00000000bffdfd80 00BBE (v01 BOCHS BXPCDSDT 00000001 BXPC 00000001) [ 0.000000] ACPI: FACS 00000000bffdfd40 00040 [ 0.000000] ACPI: SSDT 00000000bffe09b2 015FB (v01 BOCHS BXPCSSDT 00000001 BXPC 00000001) [ 0.000000] ACPI: APIC 00000000bffe1fad 000B0 (v01 BOCHS BXPCAPIC 00000001 BXPC 00000001) [ 0.000000] ACPI: SRAT 00000000bffe205d 00128 (v01 BOCHS BXPCSRAT 00000001 BXPC 00000001) [ 4.722250] Adding 33554428k swap on /data/swapfile. Priority:-2 extents:24 across:35823612k FS [ 5.841211] input: QEMU QEMU USB Tablet as /devices/pci0000:00/0000:00:01.2/usb1/1-1/1-1:1.0/input/input5 [ 5.841325] hid-generic 0003:0627:0001.0001: input,hidraw0: USB HID v0.01 Pointer [QEMU QEMU USB Tablet] on usb-0000:00:01.2-1/input0 [ 13.615575] mzoneinfo: loading out-of-tree module taints kernel. [ 13.615611] mzoneinfo: module verification failed: signature and/or required key missing - tainting kernel [ 305.100071] BUG: unable to handle kernel NULL pointer dereference at 0000000000000074 [ 305.101048] IP: [<ffffffffc02d74c0>] 0xffffffffc02d74c0 [ 305.101653] PGD 800000010d7ed067 PUD 176f9c067 PMD 0 [ 305.102276] Oops: 0000 [#1] SMP [ 305.102675] Modules linked in: tcp_diag inet_diag cirrus ttm nfit drm_kms_helper libnvdimm syscopyarea ppdev sysfillrect intel_powerclamp sysimgblt fb_sys_fops drm iosf_mbi parport_pc crc32_pclmul virtio_balloon parport ghash_clmulni_intel aesni_intel lrw gf128mul drm_panel_orientation_quirks glue_helper pcspkr i2c_piix4 joydev ablk_helper cryptd ip_tables ext4 mbcache jbd2 ata_generic pata_acpi virtio_net virtio_console net_failover virtio_blk failover ata_piix libata crct10dif_pclmul crct10dif_common crc32c_intel virtio_pci virtio_ring floppy serio_raw virtio [ 305.109021] CPU: 5 PID: 1362 Comm: AliYunDun Kdump: loaded Tainted: G OE ------------ 3.10.0-1160.15.2.el7.x86_64 #1 [ 305.110306] Hardware name: Alibaba Cloud Alibaba Cloud ECS, BIOS e623647 04/01/2014 [ 305.111150] task: ffff90f972365280 ti: ffff90f9767a4000 task.ti: ffff90f9767a4000 [ 305.111977] RIP: 0010:[<ffffffffc02d74c0>] [<ffffffffc02d74c0>] 0xffffffffc02d74c0 [ 305.112843] RSP: 0018:ffff90f9767a7b48 EFLAGS: 00010283 [ 305.113437] RAX: fffffffffffffbd0 RBX: 0000000000000240 RCX: 00000000000007cd [ 305.114228] RDX: 0000000000000000 RSI: ffff90f972365280 RDI: 00000000ffffffff [ 305.115014] RBP: ffff90f9767a7b88 R08: 0000000040000000 R09: 0000000000000400 [ 305.115804] R10: 0000000000000000 R11: ffffd9d105c1ea00 R12: 0000000000000240 [ 305.116586] R13: 0000000000000258 R14: 0000000000000018 R15: ffff90f9707aa000 [ 305.117377] FS: 00007f84fb012700(0000) GS:ffff9107ffd40000(0000) knlGS:0000000000000000 [ 305.118276] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 305.118921] CR2: 0000000000000074 CR3: 000000017839e000 CR4: 00000000003606e0 [ 305.119710] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 305.120502] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 305.121291] Call Trace: [ 305.121581] [<ffffffff92428a0c>] ? kmem_cache_alloc_trace+0x3c/0x200 [ 305.122304] [<ffffffff9242832e>] ? __kmalloc+0x2e/0x230 [ 305.122898] [<ffffffff92471d94>] ? mntput+0x24/0x40 [ 305.123458] [<ffffffff9226d3be>] ? kvm_sched_clock_read+0x1e/0x30 [ 305.124162] [<ffffffff9245fd3d>] ? putname+0x3d/0x60 [ 305.124733] [<ffffffff92994f92>] ? system_call_fastpath+0x25/0x2a [ 305.125417] Code: 65 48 8b 34 25 c0 0e 01 00 48 8b 96 30 04 00 00 48 8d 82 d0 fb ff ff 48 39 c6 74 2c 3b 7a 74 74 2a b9 d0 07 00 00 eb 0d 0f 1f 00 <3b> 7a 74 74 1b 83 e9 01 74 13 48 8b 90 30 04 00 00 48 8d 82 d0 [ 305.128647] RIP [<ffffffffc02d74c0>] 0xffffffffc02d74c0 [ 305.129263] RSP <ffff90f9767a7b48> [ 305.129660] CR2: 0000000000000074