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