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
 19mount /dev/nvme0n1 /mnt
 20echo 1 > /sys/kernel/debug/nvme0n1/fault_inject/times
 21echo 100 > /sys/kernel/debug/nvme0n1/fault_inject/probability
 22cp a.file /mnt
 23
 24Expected Result:
 25
 26cp: cannot stat ‘/mnt/a.file’: Input/output error
 27
 28Message from dmesg:
 29
 30FAULT_INJECTION: forcing a failure.
 31name fault_inject, interval 1, probability 100, space 0, times 1
 32CPU: 0 PID: 0 Comm: swapper/0 Not tainted 4.15.0-rc8+ #2
 33Hardware name: innotek GmbH VirtualBox/VirtualBox,
 34BIOS VirtualBox 12/01/2006
 35Call Trace:
 36  <IRQ>
 37  dump_stack+0x5c/0x7d
 38  should_fail+0x148/0x170
 39  nvme_should_fail+0x2f/0x50 [nvme_core]
 40  nvme_process_cq+0xe7/0x1d0 [nvme]
 41  nvme_irq+0x1e/0x40 [nvme]
 42  __handle_irq_event_percpu+0x3a/0x190
 43  handle_irq_event_percpu+0x30/0x70
 44  handle_irq_event+0x36/0x60
 45  handle_fasteoi_irq+0x78/0x120
 46  handle_irq+0xa7/0x130
 47  ? tick_irq_enter+0xa8/0xc0
 48  do_IRQ+0x43/0xc0
 49  common_interrupt+0xa2/0xa2
 50  </IRQ>
 51RIP: 0010:native_safe_halt+0x2/0x10
 52RSP: 0018:ffffffff82003e90 EFLAGS: 00000246 ORIG_RAX: ffffffffffffffdd
 53RAX: ffffffff817a10c0 RBX: ffffffff82012480 RCX: 0000000000000000
 54RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
 55RBP: 0000000000000000 R08: 000000008e38ce64 R09: 0000000000000000
 56R10: 0000000000000000 R11: 0000000000000000 R12: ffffffff82012480
 57R13: ffffffff82012480 R14: 0000000000000000 R15: 0000000000000000
 58  ? __sched_text_end+0x4/0x4
 59  default_idle+0x18/0xf0
 60  do_idle+0x150/0x1d0
 61  cpu_startup_entry+0x6f/0x80
 62  start_kernel+0x4c4/0x4e4
 63  ? set_init_arg+0x55/0x55
 64  secondary_startup_64+0xa5/0xb0
 65  print_req_error: I/O error, dev nvme0n1, sector 9240
 66EXT4-fs error (device nvme0n1): ext4_find_entry:1436:
 67inode #2: comm cp: reading directory lblock 0
 68
 69Example 2: Inject default status code with retry
 70------------------------------------------------
 71
 72mount /dev/nvme0n1 /mnt
 73echo 1 > /sys/kernel/debug/nvme0n1/fault_inject/times
 74echo 100 > /sys/kernel/debug/nvme0n1/fault_inject/probability
 75echo 1 > /sys/kernel/debug/nvme0n1/fault_inject/status
 76echo 0 > /sys/kernel/debug/nvme0n1/fault_inject/dont_retry
 77
 78cp a.file /mnt
 79
 80Expected Result:
 81
 82command success without error
 83
 84Message from dmesg:
 85
 86FAULT_INJECTION: forcing a failure.
 87name fault_inject, interval 1, probability 100, space 0, times 1
 88CPU: 1 PID: 0 Comm: swapper/1 Not tainted 4.15.0-rc8+ #4
 89Hardware name: innotek GmbH VirtualBox/VirtualBox, BIOS VirtualBox 12/01/2006
 90Call Trace:
 91  <IRQ>
 92  dump_stack+0x5c/0x7d
 93  should_fail+0x148/0x170
 94  nvme_should_fail+0x30/0x60 [nvme_core]
 95  nvme_loop_queue_response+0x84/0x110 [nvme_loop]
 96  nvmet_req_complete+0x11/0x40 [nvmet]
 97  nvmet_bio_done+0x28/0x40 [nvmet]
 98  blk_update_request+0xb0/0x310
 99  blk_mq_end_request+0x18/0x60
100  flush_smp_call_function_queue+0x3d/0xf0
101  smp_call_function_single_interrupt+0x2c/0xc0
102  call_function_single_interrupt+0xa2/0xb0
103  </IRQ>
104RIP: 0010:native_safe_halt+0x2/0x10
105RSP: 0018:ffffc9000068bec0 EFLAGS: 00000246 ORIG_RAX: ffffffffffffff04
106RAX: ffffffff817a10c0 RBX: ffff88011a3c9680 RCX: 0000000000000000
107RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
108RBP: 0000000000000001 R08: 000000008e38c131 R09: 0000000000000000
109R10: 0000000000000000 R11: 0000000000000000 R12: ffff88011a3c9680
110R13: ffff88011a3c9680 R14: 0000000000000000 R15: 0000000000000000
111  ? __sched_text_end+0x4/0x4
112  default_idle+0x18/0xf0
113  do_idle+0x150/0x1d0
114  cpu_startup_entry+0x6f/0x80
115  start_secondary+0x187/0x1e0
116  secondary_startup_64+0xa5/0xb0