Documentation/fault-injection/nvme-fault-injection.txt

   1 NVMe Fault Injection
   2 ====================
   3 Linux's fault injection framework provides a systematic way to support
   4 error injection via debugfs in the /sys/kernel/debug directory. When
   5 enabled, the default NVME_SC_INVALID_OPCODE with no retry will be
   6 injected into the nvme_end_request. Users can change the default status
   7 code and no retry flag via the debugfs. The list of Generic Command
   8 Status can be found in include/linux/nvme.h
   9
  10 Following examples show how to inject an error into the nvme.
  11
  12 First, enable CONFIG_FAULT_INJECTION_DEBUG_FS kernel config,
  13 recompile the kernel. After booting up the kernel, do the
  14 following.
  15
  16 Example 1: Inject default status code with no retry
  17 ---------------------------------------------------
  18
  19 mount /dev/nvme0n1 /mnt
  20 echo 1 > /sys/kernel/debug/nvme0n1/fault_inject/times
  21 echo 100 > /sys/kernel/debug/nvme0n1/fault_inject/probability
  22 cp a.file /mnt
  23
  24 Expected Result:
  25
  26 cp: cannot stat ‘/mnt/a.file’: Input/output error
  27
  28 Message from dmesg:
  29
  30 FAULT_INJECTION: forcing a failure.
  31 name fault_inject, interval 1, probability 100, space 0, times 1
  32 CPU: 0 PID: 0 Comm: swapper/0 Not tainted 4.15.0-rc8+ #2
  33 Hardware name: innotek GmbH VirtualBox/VirtualBox,
  34 BIOS VirtualBox 12/01/2006
  35 Call 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>
  51 RIP: 0010:native_safe_halt+0x2/0x10
  52 RSP: 0018:ffffffff82003e90 EFLAGS: 00000246 ORIG_RAX: ffffffffffffffdd
  53 RAX: ffffffff817a10c0 RBX: ffffffff82012480 RCX: 0000000000000000
  54 RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
  55 RBP: 0000000000000000 R08: 000000008e38ce64 R09: 0000000000000000
  56 R10: 0000000000000000 R11: 0000000000000000 R12: ffffffff82012480
  57 R13: 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
  66 EXT4-fs error (device nvme0n1): ext4_find_entry:1436:
  67 inode #2: comm cp: reading directory lblock 0
  68
  69 Example 2: Inject default status code with retry
  70 ------------------------------------------------
  71
  72 mount /dev/nvme0n1 /mnt
  73 echo 1 > /sys/kernel/debug/nvme0n1/fault_inject/times
  74 echo 100 > /sys/kernel/debug/nvme0n1/fault_inject/probability
  75 echo 1 > /sys/kernel/debug/nvme0n1/fault_inject/status
  76 echo 0 > /sys/kernel/debug/nvme0n1/fault_inject/dont_retry
  77
  78 cp a.file /mnt
  79
  80 Expected Result:
  81
  82 command success without error
  83
  84 Message from dmesg:
  85
  86 FAULT_INJECTION: forcing a failure.
  87 name fault_inject, interval 1, probability 100, space 0, times 1
  88 CPU: 1 PID: 0 Comm: swapper/1 Not tainted 4.15.0-rc8+ #4
  89 Hardware name: innotek GmbH VirtualBox/VirtualBox, BIOS VirtualBox 12/01/2006
  90 Call 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>
 104 RIP: 0010:native_safe_halt+0x2/0x10
 105 RSP: 0018:ffffc9000068bec0 EFLAGS: 00000246 ORIG_RAX: ffffffffffffff04
 106 RAX: ffffffff817a10c0 RBX: ffff88011a3c9680 RCX: 0000000000000000
 107 RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
 108 RBP: 0000000000000001 R08: 000000008e38c131 R09: 0000000000000000
 109 R10: 0000000000000000 R11: 0000000000000000 R12: ffff88011a3c9680
 110 R13: 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