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
117