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