Documentation: nvme: Documentation for nvme fault injection

  ALLOW_ERROR_INJECTION() macro, by setting debugfs entries

  under /sys/kernel/debug/fail_function. No boot option supported.

o NVMe fault injection

  inject NVMe status code and retry flag on devices permitted by setting

  debugfs entries under /sys/kernel/debug/nvme*/fault_inject. The default

  status code is NVME_SC_INVALID_OPCODE with no retry. The status code and

  retry flag can be set via the debugfs.

Configure fault-injection capabilities behavior

-----------------------------------------------

NVMe Fault Injection

====================

Linux's fault injection framework provides a systematic way to support

error injection via debugfs in the /sys/kernel/debug directory. When

enabled, the default NVME_SC_INVALID_OPCODE with no retry will be

injected into the nvme_end_request. Users can change the default status

code and no retry flag via the debugfs. The list of Generic Command

Status can be found in include/linux/nvme.h

Following examples show how to inject an error into the nvme.

First, enable CONFIG_FAULT_INJECTION_DEBUG_FS kernel config,

recompile the kernel. After booting up the kernel, do the

following.

Example 1: Inject default status code with no retry

---------------------------------------------------

mount /dev/nvme0n1 /mnt

echo 1 > /sys/kernel/debug/nvme0n1/fault_inject/times

echo 100 > /sys/kernel/debug/nvme0n1/fault_inject/probability

cp a.file /mnt

Expected Result:

cp: cannot stat ‘/mnt/a.file’: Input/output error

Message from dmesg:

FAULT_INJECTION: forcing a failure.

name fault_inject, interval 1, probability 100, space 0, times 1

CPU: 0 PID: 0 Comm: swapper/0 Not tainted 4.15.0-rc8+ #2

Hardware name: innotek GmbH VirtualBox/VirtualBox,

BIOS VirtualBox 12/01/2006

Call Trace:

  <IRQ>

  dump_stack+0x5c/0x7d

  should_fail+0x148/0x170

  nvme_should_fail+0x2f/0x50 [nvme_core]

  nvme_process_cq+0xe7/0x1d0 [nvme]

  nvme_irq+0x1e/0x40 [nvme]

  __handle_irq_event_percpu+0x3a/0x190

  handle_irq_event_percpu+0x30/0x70

  handle_irq_event+0x36/0x60

  handle_fasteoi_irq+0x78/0x120

  handle_irq+0xa7/0x130

  ? tick_irq_enter+0xa8/0xc0

  do_IRQ+0x43/0xc0

  common_interrupt+0xa2/0xa2

  </IRQ>

RIP: 0010:native_safe_halt+0x2/0x10

RSP: 0018:ffffffff82003e90 EFLAGS: 00000246 ORIG_RAX: ffffffffffffffdd

RAX: ffffffff817a10c0 RBX: ffffffff82012480 RCX: 0000000000000000

RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000

RBP: 0000000000000000 R08: 000000008e38ce64 R09: 0000000000000000

R10: 0000000000000000 R11: 0000000000000000 R12: ffffffff82012480

R13: ffffffff82012480 R14: 0000000000000000 R15: 0000000000000000

  ? __sched_text_end+0x4/0x4

  default_idle+0x18/0xf0

  do_idle+0x150/0x1d0

  cpu_startup_entry+0x6f/0x80

  start_kernel+0x4c4/0x4e4

  ? set_init_arg+0x55/0x55

  secondary_startup_64+0xa5/0xb0

  print_req_error: I/O error, dev nvme0n1, sector 9240

EXT4-fs error (device nvme0n1): ext4_find_entry:1436:

inode #2: comm cp: reading directory lblock 0

Example 2: Inject default status code with retry

------------------------------------------------

mount /dev/nvme0n1 /mnt

echo 1 > /sys/kernel/debug/nvme0n1/fault_inject/times

echo 100 > /sys/kernel/debug/nvme0n1/fault_inject/probability

echo 1 > /sys/kernel/debug/nvme0n1/fault_inject/status

echo 0 > /sys/kernel/debug/nvme0n1/fault_inject/dont_retry

cp a.file /mnt

Expected Result:

command success without error

Message from dmesg:

FAULT_INJECTION: forcing a failure.

name fault_inject, interval 1, probability 100, space 0, times 1

CPU: 1 PID: 0 Comm: swapper/1 Not tainted 4.15.0-rc8+ #4

Hardware name: innotek GmbH VirtualBox/VirtualBox, BIOS VirtualBox 12/01/2006

Call Trace:

  <IRQ>

  dump_stack+0x5c/0x7d

  should_fail+0x148/0x170

  nvme_should_fail+0x30/0x60 [nvme_core]

  nvme_loop_queue_response+0x84/0x110 [nvme_loop]

  nvmet_req_complete+0x11/0x40 [nvmet]

  nvmet_bio_done+0x28/0x40 [nvmet]

  blk_update_request+0xb0/0x310

  blk_mq_end_request+0x18/0x60

  flush_smp_call_function_queue+0x3d/0xf0

  smp_call_function_single_interrupt+0x2c/0xc0

  call_function_single_interrupt+0xa2/0xb0

  </IRQ>

RIP: 0010:native_safe_halt+0x2/0x10

RSP: 0018:ffffc9000068bec0 EFLAGS: 00000246 ORIG_RAX: ffffffffffffff04

RAX: ffffffff817a10c0 RBX: ffff88011a3c9680 RCX: 0000000000000000

RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000

RBP: 0000000000000001 R08: 000000008e38c131 R09: 0000000000000000

R10: 0000000000000000 R11: 0000000000000000 R12: ffff88011a3c9680

R13: ffff88011a3c9680 R14: 0000000000000000 R15: 0000000000000000

  ? __sched_text_end+0x4/0x4

  default_idle+0x18/0xf0

  do_idle+0x150/0x1d0

  cpu_startup_entry+0x6f/0x80

  start_secondary+0x187/0x1e0

  secondary_startup_64+0xa5/0xb0