1NVMe Fault Injection 2==================== 3Linux's fault injection framework provides a systematic way to support 4error injection via debugfs in the /sys/kernel/debug directory. When 5enabled, the default NVME_SC_INVALID_OPCODE with no retry will be 6injected into the nvme_end_request. Users can change the default status 7code and no retry flag via the debugfs. The list of Generic Command 8Status can be found in include/linux/nvme.h 9 10Following examples show how to inject an error into the nvme. 11 12First, enable CONFIG_FAULT_INJECTION_DEBUG_FS kernel config, 13recompile the kernel. After booting up the kernel, do the 14following. 15 16Example 1: Inject default status code with no retry 17--------------------------------------------------- 18 19:: 20 21 mount /dev/nvme0n1 /mnt 22 echo 1 > /sys/kernel/debug/nvme0n1/fault_inject/times 23 echo 100 > /sys/kernel/debug/nvme0n1/fault_inject/probability 24 cp a.file /mnt 25 26Expected Result:: 27 28 cp: cannot stat ‘/mnt/a.file’: Input/output error 29 30Message from dmesg:: 31 32 FAULT_INJECTION: forcing a failure. 33 name fault_inject, interval 1, probability 100, space 0, times 1 34 CPU: 0 PID: 0 Comm: swapper/0 Not tainted 4.15.0-rc8+ #2 35 Hardware name: innotek GmbH VirtualBox/VirtualBox, 36 BIOS VirtualBox 12/01/2006 37 Call Trace: 38 <IRQ> 39 dump_stack+0x5c/0x7d 40 should_fail+0x148/0x170 41 nvme_should_fail+0x2f/0x50 [nvme_core] 42 nvme_process_cq+0xe7/0x1d0 [nvme] 43 nvme_irq+0x1e/0x40 [nvme] 44 __handle_irq_event_percpu+0x3a/0x190 45 handle_irq_event_percpu+0x30/0x70 46 handle_irq_event+0x36/0x60 47 handle_fasteoi_irq+0x78/0x120 48 handle_irq+0xa7/0x130 49 ? tick_irq_enter+0xa8/0xc0 50 do_IRQ+0x43/0xc0 51 common_interrupt+0xa2/0xa2 52 </IRQ> 53 RIP: 0010:native_safe_halt+0x2/0x10 54 RSP: 0018:ffffffff82003e90 EFLAGS: 00000246 ORIG_RAX: ffffffffffffffdd 55 RAX: ffffffff817a10c0 RBX: ffffffff82012480 RCX: 0000000000000000 56 RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000 57 RBP: 0000000000000000 R08: 000000008e38ce64 R09: 0000000000000000 58 R10: 0000000000000000 R11: 0000000000000000 R12: ffffffff82012480 59 R13: ffffffff82012480 R14: 0000000000000000 R15: 0000000000000000 60 ? __sched_text_end+0x4/0x4 61 default_idle+0x18/0xf0 62 do_idle+0x150/0x1d0 63 cpu_startup_entry+0x6f/0x80 64 start_kernel+0x4c4/0x4e4 65 ? set_init_arg+0x55/0x55 66 secondary_startup_64+0xa5/0xb0 67 print_req_error: I/O error, dev nvme0n1, sector 9240 68 EXT4-fs error (device nvme0n1): ext4_find_entry:1436: 69 inode #2: comm cp: reading directory lblock 0 70 71Example 2: Inject default status code with retry 72------------------------------------------------ 73 74:: 75 76 mount /dev/nvme0n1 /mnt 77 echo 1 > /sys/kernel/debug/nvme0n1/fault_inject/times 78 echo 100 > /sys/kernel/debug/nvme0n1/fault_inject/probability 79 echo 1 > /sys/kernel/debug/nvme0n1/fault_inject/status 80 echo 0 > /sys/kernel/debug/nvme0n1/fault_inject/dont_retry 81 82 cp a.file /mnt 83 84Expected Result:: 85 86 command success without error 87 88Message from dmesg:: 89 90 FAULT_INJECTION: forcing a failure. 91 name fault_inject, interval 1, probability 100, space 0, times 1 92 CPU: 1 PID: 0 Comm: swapper/1 Not tainted 4.15.0-rc8+ #4 93 Hardware name: innotek GmbH VirtualBox/VirtualBox, BIOS VirtualBox 12/01/2006 94 Call Trace: 95 <IRQ> 96 dump_stack+0x5c/0x7d 97 should_fail+0x148/0x170 98 nvme_should_fail+0x30/0x60 [nvme_core] 99 nvme_loop_queue_response+0x84/0x110 [nvme_loop] 100 nvmet_req_complete+0x11/0x40 [nvmet] 101 nvmet_bio_done+0x28/0x40 [nvmet] 102 blk_update_request+0xb0/0x310 103 blk_mq_end_request+0x18/0x60 104 flush_smp_call_function_queue+0x3d/0xf0 105 smp_call_function_single_interrupt+0x2c/0xc0 106 call_function_single_interrupt+0xa2/0xb0 107 </IRQ> 108 RIP: 0010:native_safe_halt+0x2/0x10 109 RSP: 0018:ffffc9000068bec0 EFLAGS: 00000246 ORIG_RAX: ffffffffffffff04 110 RAX: ffffffff817a10c0 RBX: ffff88011a3c9680 RCX: 0000000000000000 111 RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000 112 RBP: 0000000000000001 R08: 000000008e38c131 R09: 0000000000000000 113 R10: 0000000000000000 R11: 0000000000000000 R12: ffff88011a3c9680 114 R13: ffff88011a3c9680 R14: 0000000000000000 R15: 0000000000000000 115 ? __sched_text_end+0x4/0x4 116 default_idle+0x18/0xf0 117 do_idle+0x150/0x1d0 118 cpu_startup_entry+0x6f/0x80 119 start_secondary+0x187/0x1e0 120 secondary_startup_64+0xa5/0xb0 121