江苏宏远建设集团网站,wordpress用户个人页面,公司内部网站维护,建设企业网站官网u盾SysRq键简介
SysRq键是一个魔术案件#xff0c;只要在内核没有完全卡死的情况下#xff0c;内核都会相应SysRq 键的输入#xff0c;使用这些组合键都可以搜集包括系统内存使用、CPU任务处理、进程运行状态等系统运行信息。
配置
内核配置选项中要使能CONFIG_MAGIC_SYSRQ选…SysRq键简介
SysRq键是一个魔术案件只要在内核没有完全卡死的情况下内核都会相应SysRq 键的输入使用这些组合键都可以搜集包括系统内存使用、CPU任务处理、进程运行状态等系统运行信息。
配置
内核配置选项中要使能CONFIG_MAGIC_SYSRQ选项这样系统启动之后会生成/proc/sysrq-trigger节点用于调试。
修改/etc/sysctl.conf启动SysRq。
kernel.sysrq1执行下列命令使修改生效。
sysctl -p也可以通过写echo number /proc/sys/kernel/sysrq节点临时使能sysrq功能。
写入不同的值使能不同的功能
值描述/说明0完全禁用 sysrq1启用 sysrq 的所有功能2允许控制终端日志级别4允许控制终端日志级别8允许调试进程dump16允许执行sync命令32允许重新挂载文件系统为之读64允许发送信号给进程(term,kill,oom-kill)128允许重启/关机256允许调整实时任务的优先级
如何使用SysRq
echo command key /proc/sysrq-trigger命令键 command key 是区分大小写的。 command key 具体含义如下。
命令键功能b将立即重启系统不会同步或者卸载磁盘。c将执行系统 crash如果配置了系统 crashdump将执行 crashdump。d显示所有持有的锁。e发送 SIGTERM 信号给所有进程除了 init 进程。f将调用 oom killer 杀掉一个过度占用内存的进程如果什么任务都没杀 也不会 panic。gkgdb 使用内核调试器。h将会显示帮助。实际上除了这里列举的键其他的都将显示帮助 但是 h 容易记住i发送 SIGKILL 给所有进程除了 init 进程。j强制性的 “解冻它” - 用于被 FIFREEZE ioctl 操作冻住的文件系统。k安全访问秘钥(SAK)杀掉在当前虚拟控制台的所有程序注意参考 下面 SAK 节重要论述。l显示所有活动 cpu 的栈回溯。m将导出当前内存信息到你的控制台。n用于使所有实时任务变成普通任务。o将关闭系统如果配置和支持的话。p将导出当前寄存器和标志位到控制台。q将导出每个 cpu 上所有已装备的高精度定时器不是完整的 time_list 文件显示的 timers和所有时钟事件设备的详细信息。r关闭键盘的原始模式设置为转换模式。s将尝试同步所有的已挂载文件系统。t将导出当前所有任务列表和它们的信息到控制台。u将尝试重新挂载已挂载文件系统为只读。v强制恢复帧缓存控制台。v触发 ETM 缓存导出 [ARM 架构特有]w导出处于不可中断状态阻塞的任务。x在 ppc/powerpc 架构上用于 xmon 接口。 在 sparc64 架构上用于显示全局的 PMU性能监控单元寄存器。 在 MIPS 架构上导出所有的 tlb 条目。y显示全局 cpu 寄存器 [SPARC-64 架构特有]z导出 ftrace 缓存信息0-9设置控制台日志级别该级别控制什么样的内核信息将被打印到你的 控制台。比如 0 将使得只有紧急信息像 PANICs or OOPSes 才能到你的控制台。
打印内存使用信息
rootfirefly:~# echo m /proc/sysrq-trigger
[ 3100.196187] sysrq: SysRq : Show Memory
[ 3100.196675] Mem-Info:
[ 3100.196931] active_anon:48062 inactive_anon:2987 isolated_anon:0
[ 3100.196931] active_file:40449 inactive_file:53540 isolated_file:0
[ 3100.196931] unevictable:0 dirty:22 writeback:0 unstable:0
[ 3100.196931] slab_reclaimable:10518 slab_unreclaimable:6599
[ 3100.196931] mapped:44843 shmem:3710 pagetables:1568 bounce:0
[ 3100.196931] free:810482 free_pcp:497 free_cma:0
[ 3100.199998] DMA free:3241928kB min:7920kB low:9900kB high:11880kB active_anon:192248kB inactive_anon:11948kB active_file:161796kB inactive_file:214160kB unevictable:0kB isolated(anon):0kB isolated(file):0kB present:4030464kB managed:3933592kB mlocked:0kB dirty:88kB writeback:0kB mapped:179372kB shmem:14840kB slab_reclaimable:42072kB slab_unreclaimable:26396kB kernel_stack:5792kB pagetables:6272kB unstable:0kB bounce:0kB free_pcp:1988kB local_pcp:224kB free_cma:0kB writeback_tmp:0kB pages_scanned:0 all_unreclaimable? no
[ 3100.204031] lowmem_reserve[]: 0 0 0
[ 3100.204414] DMA: 272*4kB (U) 95*8kB (UM) 177*16kB (UME) 88*32kB (UME) 50*64kB (UM) 32*128kB (UM) 6*256kB (UM) 4*512kB (UM) 2*1024kB (M) 3*2048kB (UME) 785*4096kB (M) 3241928kB
[ 3100.206208] Node 0 hugepages_total0 hugepages_free0 hugepages_surp0 hugepages_size2048kB
[ 3100.206990] 97710 total pagecache pages
[ 3100.207345] 0 pages in swap cache
[ 3100.207679] Swap cache stats: add 0, delete 0, find 0/0
[ 3100.208156] Free swap 0kB
[ 3100.208425] Total swap 0kB
[ 3100.208721] 1007616 pages RAM
[ 3100.209003] 0 pages HighMem/MovableOnly
[ 3100.209352] 24218 pages reserved
rootfirefly:~# 打印进程列表
rootfirefly:~# echo t /proc/sysrq-trigger
[ 3357.426399] sysrq: SysRq : Show State
[ 3357.426902] Call trace:
[ 3357.427155] [ffffff8008085048] __switch_to0x94/0xbc
[ 3357.427759] [ffffff8008eee8cc] __schedule0x334/0x65c
[ 3357.428249] [ffffff8008eeec64] schedule0x70/0x84
[ 3357.428762] [ffffff8008ef175c] schedule_hrtimeout_range_clock0x54/0xd8
[ 3357.429390] [ffffff8008ef1818] schedule_hrtimeout_range0x38/0x48
[ 3357.430004] [ffffff80082286e8] SyS_epoll_wait0x2c0/0x334
[ 3357.430515] [ffffff8008228810] SyS_epoll_pwait0xb4/0x104
[ 3357.431057] [ffffff8008082f70] el0_svc_naked0x24/0x28
[ 3357.431576] Call trace:
[ 3359.224688] runnable tasks:
[ 3359.224688] task PID tree-key switches prio wait-time sum-exec sum-sleep
[ 3359.224688] ----------------------------------------------------------------------------------------------------------
[ 3359.226942] watchdog/5 31 -8.990375 842 0 0.010418 33.639974 0.011083 /
[ 3359.227935] migration/5 32 0.000000 11 0 0.006417 0.703626 0.011083 /
...............................
[ 3359.280491] rsyslogd 620 12549.402602 31 120 3.959710 13.067249 3000146.370846 /
[ 3359.281483] gmain 649 2780.837080 4 120 1.497875 0.234791 42.333083 /
[ 3359.282473] gdbus 653 6084.558463 235 120 11.845505 88.143377 5894.875470 /
[ 3359.283464] probing-thread 657 2798.851658 1 120 0.171209 0.046375 0.000000 /
[ 3359.284458] gmain 666 13129.747017 842 120 1.635792 160.937875 ...............................
[ 3359.347891] kbase_event 1087 5737.991190 2 100 0.000000 0.015416 0.022167 /
[ 3359.348888] kworker/5:0 1415 12729.712418 6352 120 94.661328 379.266952 300531.917073 /
[ 3359.349880] kworker/5:1 1421 13139.623478 4592 120 40.804756 269.058278 218093.165092 /
[ 3359.350919] 打印 CPU 信息
rootfirefly:~# echo w /proc/sysrq-trigger
[ 3461.098259] sysrq: SysRq : Show Blocked State
[ 3461.099495] Sched Debug Version: v0.11, 4.4.194 #15
[ 3461.099987] ktime : 3460974.551474
[ 3461.100559] sched_clk : 3461099.486338
[ 3461.101163] cpu_clk : 3461099.486629
[ 3461.101733] jiffies : 4298128273
[ 3461.102303]
[ 3461.102457] sysctl_sched
...............................
[ 3461.106084]
[ 3461.476753] task PID tree-key switches prio wait-time sum-exec sum-sleep
[ 3461.476753] ----------------------------------------------------------------------------------------------------------
[ 3461.479007] watchdog/5 31 -8.990375 868 0 0.010418 34.639809 0.011083 /
[ 3461.479999] migration/5 32 0.000000 11 0 0.006417 0.703626 0.011083 /
[ 3461.480990] ksoftirqd/5 33 12976.655002 282 120 31.262910 9.577926 3226896.156313 /
....................
[ 3461.598951] gdbus 981 5621.043245 63 120 10.429415 7.925751 240.024166 /
[ 3461.599945] kbase_event 1087 5737.991190 2 100 0.000000 0.015416 0.022167 /
[ 3461.600943] kworker/5:1 1421 13242.484431 6324 120 56.331917 371.919231 300578.331580 /
[ 3461.601934] kworker/5:0 1424 13267.128801 416 120 3.932261 25.079662 19671.560460 /
[ 3461.602964] 显示所有活动 cpu 的栈回溯
rootfirefly:~# echo l /proc/sysrq-trigger
[ 3602.003162] sysrq: SysRq : Show backtrace of all active CPUs
[ 3602.003919] Call trace:
[ 3602.004175] [ffffff8008088300] dump_backtrace0x0/0x220
rootfirefly:~# [ 3602.004675] [ffffff8008088544] show_stack0x24/0x30
[ 3602.005233] [ffffff80085bbdac] showacpu0x68/0x84
[ 3602.005688] [ffffff8008134b68] flush_smp_call_function_queue0x84/0x134
[ 3602.006303] [ffffff8008135584] generic_smp_call_function_single_interrupt0x18/0x20
[ 3602.007007] [ffffff800808cba4] handle_IPI0x19c/0x260
[ 3602.007490] [ffffff8008080eec] gic_handle_irq0x12c/0x184
[ 3602.007995] Exception stack(0xffffffc0f2f1fd90 to 0xffffffc0f2f1fec0)
[ 3602.008580] fd80: 0000000000000000 0000000000000003
[ 3602.009284] fda0: 00000040ee976000 0000000000000020 00ffffffffffffff 0000001425865f85
[ 3602.009988] fdc0: 000000000004b382 0000000000000003 00000032b5593519 ffffff8008081800
[ 3602.010691] fde0: 0000000000001000 0000000000000000 0000000034d5d91d 00000040ee976000
[ 3602.011394] fe00: ffffffc0f2f0a880 0000000000000000 0000000000000000 0000000000000000
[ 3602.012098] fe20: 0000000030d00800 00000346a09ab464 0000000000000002 ffffffc00a4bac00
[ 3602.012801] fe40: ffffff80097ace18 0000000000000001 0000034697fd8ddd ffffff800974e488
[ 3602.013504] fe60: 0000000001ab4000 00000000010f8244 0000000000000000 ffffffc0f2f1fec0
[ 3602.014209] fe80: ffffff8008b9eb10 ffffffc0f2f1fec0 ffffff8008b9eb14 0000000060000145
[ 3602.014912] fea0: ffffffc0f2f1fec0 ffffff8008b9eb10 ffffffffffffffff 0000000000000002
[ 3602.015615] [ffffff80080827b4] el1_irq0xb4/0x140
[ 3602.016070] [ffffff8008b9eb14] cpuidle_enter_state0x1cc/0x25c
[ 3602.016624] [ffffff8008b9ec18] cpuidle_enter0x34/0x44
[ 3602.017112] [ffffff80081004e4] call_cpuidle0x6c/0x74
[ 3602.017598] [ffffff8008100798] cpu_startup_entry0x2ac/0x2bc
[ 3602.018128] [ffffff800808c5b0] secondary_start_kernel0x190/0x1bc
[ 3602.018700] [00000000010f8188] 0x10f8188触发 Crashdump
rootfirefly:~# echo c /proc/sysrq-trigger
[ 3635.905960] sysrq: SysRq : Trigger a crash
[ 3635.906476] Unable to handle kernel NULL pointer dereference at virtual address 00000000
[ 3635.907201] pgd ffffffc0d4a3e000
[ 3635.907640] [00000000] *pgd0000000000000000, *pud0000000000000000
[ 3635.908305] Internal error: Oops: 96000045 [#1] SMP
..............................................................
[ 3648.331820] Exception stack(0xffffffc0cd8cbb30 to 0xffffffc0cd8cbc60)
[ 3648.332405] bb20: ffffff800967ff68 0000008000000000
[ 3648.333108] bb40: ffffffc0cd8cbd00 ffffff80085bb538 000000000000000f 0000000000000000
[ 3648.333811] bb60: ffffff80097f72f8 0000000000000002 ffffffc0cd8cbb90 000000030003c018
[ 3648.334514] bb80: 00000000000000c3 0000000100000000 ffffffc0cd8cbc30 ffffff800810d674
[ 3648.335218] bba0: ffffffc0cd8cbc90 ffffff80092b55d1 ffffff80095fa000 0000000000000006
[ 3648.335921] bbc0: 0000000000000063 0000000000000000 0000000000000001 0000000000000000
[ 3648.336623] bbe0: ffffffc0f7ee8320 0000000000000000 0000000000000000 0000000000000000
[ 3648.337327] bc00: 0000000000000010 ffffff800965ead8 ffffff8008478398 7f7f7f7f7f7f7f7f
[ 3648.338029] bc20: 71277660716d73ff 7f7f7f7f7f7f7f7f 0101010101010101 0000000000000000
[ 3648.338733] bc40: 0ffffffffffffffe 0000000000000000 ffffff80081e5cb8 0000007f8147b8c8
[ 3648.339434] [ffffff80080825cc] el1_da0x24/0x8c
[ 3648.339873] [ffffff80085bc008] __handle_sysrq0xa0/0x14c
[ 3648.340379] [ffffff80085bc434] write_sysrq_trigger0x5c/0x74
[ 3648.340911] [ffffff8008240cf4] proc_reg_write0xa8/0xcc
[ 3648.341406] [ffffff80081e4a88] __vfs_write0x48/0xe8
[ 3648.341877] [ffffff80081e5374] vfs_write0xa8/0x15c
[ 3648.342338] [ffffff80081e5d14] SyS_write0x5c/0xb0
[ 3648.342798] [ffffff8008082f70] el0_svc_naked0x24/0x28总结
SysRq 在处理系统挂起时安全重启方面已经比较完善了。
https://blog.csdn.net/QTM_Gitee/article/details/122929292
https://blog.csdn.net/weixin_42506599/article/details/108411139
https://www.codenong.com/cs106961584/
https://www.kernel.org/doc/html/latest/translations/zh_CN/admin-guide/sysrq.html?highlightsysrq
https://blog.csdn.net/zhangzhi123456789/article/details/47088253
