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Diffstat (limited to '')
| -rw-r--r-- | Documentation/fault-injection/fault-injection.txt | 435 | ||||
| -rw-r--r-- | Documentation/fault-injection/notifier-error-inject.txt | 94 | ||||
| -rw-r--r-- | Documentation/fault-injection/nvme-fault-injection.txt | 116 | ||||
| -rw-r--r-- | Documentation/fault-injection/provoke-crashes.txt | 38 |
4 files changed, 683 insertions, 0 deletions
diff --git a/Documentation/fault-injection/fault-injection.txt b/Documentation/fault-injection/fault-injection.txt new file mode 100644 index 000000000..4d1b7b4cc --- /dev/null +++ b/Documentation/fault-injection/fault-injection.txt @@ -0,0 +1,435 @@ +Fault injection capabilities infrastructure +=========================================== + +See also drivers/md/md-faulty.c and "every_nth" module option for scsi_debug. + + +Available fault injection capabilities +-------------------------------------- + +o failslab + + injects slab allocation failures. (kmalloc(), kmem_cache_alloc(), ...) + +o fail_page_alloc + + injects page allocation failures. (alloc_pages(), get_free_pages(), ...) + +o fail_futex + + injects futex deadlock and uaddr fault errors. + +o fail_make_request + + injects disk IO errors on devices permitted by setting + /sys/block/<device>/make-it-fail or + /sys/block/<device>/<partition>/make-it-fail. (generic_make_request()) + +o fail_mmc_request + + injects MMC data errors on devices permitted by setting + debugfs entries under /sys/kernel/debug/mmc0/fail_mmc_request + +o fail_function + + injects error return on specific functions, which are marked by + 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 +----------------------------------------------- + +o debugfs entries + +fault-inject-debugfs kernel module provides some debugfs entries for runtime +configuration of fault-injection capabilities. + +- /sys/kernel/debug/fail*/probability: + + likelihood of failure injection, in percent. + Format: <percent> + + Note that one-failure-per-hundred is a very high error rate + for some testcases. Consider setting probability=100 and configure + /sys/kernel/debug/fail*/interval for such testcases. + +- /sys/kernel/debug/fail*/interval: + + specifies the interval between failures, for calls to + should_fail() that pass all the other tests. + + Note that if you enable this, by setting interval>1, you will + probably want to set probability=100. + +- /sys/kernel/debug/fail*/times: + + specifies how many times failures may happen at most. + A value of -1 means "no limit". + +- /sys/kernel/debug/fail*/space: + + specifies an initial resource "budget", decremented by "size" + on each call to should_fail(,size). Failure injection is + suppressed until "space" reaches zero. + +- /sys/kernel/debug/fail*/verbose + + Format: { 0 | 1 | 2 } + specifies the verbosity of the messages when failure is + injected. '0' means no messages; '1' will print only a single + log line per failure; '2' will print a call trace too -- useful + to debug the problems revealed by fault injection. + +- /sys/kernel/debug/fail*/task-filter: + + Format: { 'Y' | 'N' } + A value of 'N' disables filtering by process (default). + Any positive value limits failures to only processes indicated by + /proc/<pid>/make-it-fail==1. + +- /sys/kernel/debug/fail*/require-start: +- /sys/kernel/debug/fail*/require-end: +- /sys/kernel/debug/fail*/reject-start: +- /sys/kernel/debug/fail*/reject-end: + + specifies the range of virtual addresses tested during + stacktrace walking. Failure is injected only if some caller + in the walked stacktrace lies within the required range, and + none lies within the rejected range. + Default required range is [0,ULONG_MAX) (whole of virtual address space). + Default rejected range is [0,0). + +- /sys/kernel/debug/fail*/stacktrace-depth: + + specifies the maximum stacktrace depth walked during search + for a caller within [require-start,require-end) OR + [reject-start,reject-end). + +- /sys/kernel/debug/fail_page_alloc/ignore-gfp-highmem: + + Format: { 'Y' | 'N' } + default is 'N', setting it to 'Y' won't inject failures into + highmem/user allocations. + +- /sys/kernel/debug/failslab/ignore-gfp-wait: +- /sys/kernel/debug/fail_page_alloc/ignore-gfp-wait: + + Format: { 'Y' | 'N' } + default is 'N', setting it to 'Y' will inject failures + only into non-sleep allocations (GFP_ATOMIC allocations). + +- /sys/kernel/debug/fail_page_alloc/min-order: + + specifies the minimum page allocation order to be injected + failures. + +- /sys/kernel/debug/fail_futex/ignore-private: + + Format: { 'Y' | 'N' } + default is 'N', setting it to 'Y' will disable failure injections + when dealing with private (address space) futexes. + +- /sys/kernel/debug/fail_function/inject: + + Format: { 'function-name' | '!function-name' | '' } + specifies the target function of error injection by name. + If the function name leads '!' prefix, given function is + removed from injection list. If nothing specified ('') + injection list is cleared. + +- /sys/kernel/debug/fail_function/injectable: + + (read only) shows error injectable functions and what type of + error values can be specified. The error type will be one of + below; + - NULL: retval must be 0. + - ERRNO: retval must be -1 to -MAX_ERRNO (-4096). + - ERR_NULL: retval must be 0 or -1 to -MAX_ERRNO (-4096). + +- /sys/kernel/debug/fail_function/<functiuon-name>/retval: + + specifies the "error" return value to inject to the given + function for given function. This will be created when + user specifies new injection entry. + +o Boot option + +In order to inject faults while debugfs is not available (early boot time), +use the boot option: + + failslab= + fail_page_alloc= + fail_make_request= + fail_futex= + mmc_core.fail_request=<interval>,<probability>,<space>,<times> + +o proc entries + +- /proc/<pid>/fail-nth: +- /proc/self/task/<tid>/fail-nth: + + Write to this file of integer N makes N-th call in the task fail. + Read from this file returns a integer value. A value of '0' indicates + that the fault setup with a previous write to this file was injected. + A positive integer N indicates that the fault wasn't yet injected. + Note that this file enables all types of faults (slab, futex, etc). + This setting takes precedence over all other generic debugfs settings + like probability, interval, times, etc. But per-capability settings + (e.g. fail_futex/ignore-private) take precedence over it. + + This feature is intended for systematic testing of faults in a single + system call. See an example below. + +How to add new fault injection capability +----------------------------------------- + +o #include <linux/fault-inject.h> + +o define the fault attributes + + DECLARE_FAULT_INJECTION(name); + + Please see the definition of struct fault_attr in fault-inject.h + for details. + +o provide a way to configure fault attributes + +- boot option + + If you need to enable the fault injection capability from boot time, you can + provide boot option to configure it. There is a helper function for it: + + setup_fault_attr(attr, str); + +- debugfs entries + + failslab, fail_page_alloc, and fail_make_request use this way. + Helper functions: + + fault_create_debugfs_attr(name, parent, attr); + +- module parameters + + If the scope of the fault injection capability is limited to a + single kernel module, it is better to provide module parameters to + configure the fault attributes. + +o add a hook to insert failures + + Upon should_fail() returning true, client code should inject a failure. + + should_fail(attr, size); + +Application Examples +-------------------- + +o Inject slab allocation failures into module init/exit code + +#!/bin/bash + +FAILTYPE=failslab +echo Y > /sys/kernel/debug/$FAILTYPE/task-filter +echo 10 > /sys/kernel/debug/$FAILTYPE/probability +echo 100 > /sys/kernel/debug/$FAILTYPE/interval +echo -1 > /sys/kernel/debug/$FAILTYPE/times +echo 0 > /sys/kernel/debug/$FAILTYPE/space +echo 2 > /sys/kernel/debug/$FAILTYPE/verbose +echo 1 > /sys/kernel/debug/$FAILTYPE/ignore-gfp-wait + +faulty_system() +{ + bash -c "echo 1 > /proc/self/make-it-fail && exec $*" +} + +if [ $# -eq 0 ] +then + echo "Usage: $0 modulename [ modulename ... ]" + exit 1 +fi + +for m in $* +do + echo inserting $m... + faulty_system modprobe $m + + echo removing $m... + faulty_system modprobe -r $m +done + +------------------------------------------------------------------------------ + +o Inject page allocation failures only for a specific module + +#!/bin/bash + +FAILTYPE=fail_page_alloc +module=$1 + +if [ -z $module ] +then + echo "Usage: $0 <modulename>" + exit 1 +fi + +modprobe $module + +if [ ! -d /sys/module/$module/sections ] +then + echo Module $module is not loaded + exit 1 +fi + +cat /sys/module/$module/sections/.text > /sys/kernel/debug/$FAILTYPE/require-start +cat /sys/module/$module/sections/.data > /sys/kernel/debug/$FAILTYPE/require-end + +echo N > /sys/kernel/debug/$FAILTYPE/task-filter +echo 10 > /sys/kernel/debug/$FAILTYPE/probability +echo 100 > /sys/kernel/debug/$FAILTYPE/interval +echo -1 > /sys/kernel/debug/$FAILTYPE/times +echo 0 > /sys/kernel/debug/$FAILTYPE/space +echo 2 > /sys/kernel/debug/$FAILTYPE/verbose +echo 1 > /sys/kernel/debug/$FAILTYPE/ignore-gfp-wait +echo 1 > /sys/kernel/debug/$FAILTYPE/ignore-gfp-highmem +echo 10 > /sys/kernel/debug/$FAILTYPE/stacktrace-depth + +trap "echo 0 > /sys/kernel/debug/$FAILTYPE/probability" SIGINT SIGTERM EXIT + +echo "Injecting errors into the module $module... (interrupt to stop)" +sleep 1000000 + +------------------------------------------------------------------------------ + +o Inject open_ctree error while btrfs mount + +#!/bin/bash + +rm -f testfile.img +dd if=/dev/zero of=testfile.img bs=1M seek=1000 count=1 +DEVICE=$(losetup --show -f testfile.img) +mkfs.btrfs -f $DEVICE +mkdir -p tmpmnt + +FAILTYPE=fail_function +FAILFUNC=open_ctree +echo $FAILFUNC > /sys/kernel/debug/$FAILTYPE/inject +echo -12 > /sys/kernel/debug/$FAILTYPE/$FAILFUNC/retval +echo N > /sys/kernel/debug/$FAILTYPE/task-filter +echo 100 > /sys/kernel/debug/$FAILTYPE/probability +echo 0 > /sys/kernel/debug/$FAILTYPE/interval +echo -1 > /sys/kernel/debug/$FAILTYPE/times +echo 0 > /sys/kernel/debug/$FAILTYPE/space +echo 1 > /sys/kernel/debug/$FAILTYPE/verbose + +mount -t btrfs $DEVICE tmpmnt +if [ $? -ne 0 ] +then + echo "SUCCESS!" +else + echo "FAILED!" + umount tmpmnt +fi + +echo > /sys/kernel/debug/$FAILTYPE/inject + +rmdir tmpmnt +losetup -d $DEVICE +rm testfile.img + + +Tool to run command with failslab or fail_page_alloc +---------------------------------------------------- +In order to make it easier to accomplish the tasks mentioned above, we can use +tools/testing/fault-injection/failcmd.sh. Please run a command +"./tools/testing/fault-injection/failcmd.sh --help" for more information and +see the following examples. + +Examples: + +Run a command "make -C tools/testing/selftests/ run_tests" with injecting slab +allocation failure. + + # ./tools/testing/fault-injection/failcmd.sh \ + -- make -C tools/testing/selftests/ run_tests + +Same as above except to specify 100 times failures at most instead of one time +at most by default. + + # ./tools/testing/fault-injection/failcmd.sh --times=100 \ + -- make -C tools/testing/selftests/ run_tests + +Same as above except to inject page allocation failure instead of slab +allocation failure. + + # env FAILCMD_TYPE=fail_page_alloc \ + ./tools/testing/fault-injection/failcmd.sh --times=100 \ + -- make -C tools/testing/selftests/ run_tests + +Systematic faults using fail-nth +--------------------------------- + +The following code systematically faults 0-th, 1-st, 2-nd and so on +capabilities in the socketpair() system call. + +#include <sys/types.h> +#include <sys/stat.h> +#include <sys/socket.h> +#include <sys/syscall.h> +#include <fcntl.h> +#include <unistd.h> +#include <string.h> +#include <stdlib.h> +#include <stdio.h> +#include <errno.h> + +int main() +{ + int i, err, res, fail_nth, fds[2]; + char buf[128]; + + system("echo N > /sys/kernel/debug/failslab/ignore-gfp-wait"); + sprintf(buf, "/proc/self/task/%ld/fail-nth", syscall(SYS_gettid)); + fail_nth = open(buf, O_RDWR); + for (i = 1;; i++) { + sprintf(buf, "%d", i); + write(fail_nth, buf, strlen(buf)); + res = socketpair(AF_LOCAL, SOCK_STREAM, 0, fds); + err = errno; + pread(fail_nth, buf, sizeof(buf), 0); + if (res == 0) { + close(fds[0]); + close(fds[1]); + } + printf("%d-th fault %c: res=%d/%d\n", i, atoi(buf) ? 'N' : 'Y', + res, err); + if (atoi(buf)) + break; + } + return 0; +} + +An example output: + +1-th fault Y: res=-1/23 +2-th fault Y: res=-1/23 +3-th fault Y: res=-1/12 +4-th fault Y: res=-1/12 +5-th fault Y: res=-1/23 +6-th fault Y: res=-1/23 +7-th fault Y: res=-1/23 +8-th fault Y: res=-1/12 +9-th fault Y: res=-1/12 +10-th fault Y: res=-1/12 +11-th fault Y: res=-1/12 +12-th fault Y: res=-1/12 +13-th fault Y: res=-1/12 +14-th fault Y: res=-1/12 +15-th fault Y: res=-1/12 +16-th fault N: res=0/12 diff --git a/Documentation/fault-injection/notifier-error-inject.txt b/Documentation/fault-injection/notifier-error-inject.txt new file mode 100644 index 000000000..e861d761d --- /dev/null +++ b/Documentation/fault-injection/notifier-error-inject.txt @@ -0,0 +1,94 @@ +Notifier error injection +======================== + +Notifier error injection provides the ability to inject artificial errors to +specified notifier chain callbacks. It is useful to test the error handling of +notifier call chain failures which is rarely executed. There are kernel +modules that can be used to test the following notifiers. + + * PM notifier + * Memory hotplug notifier + * powerpc pSeries reconfig notifier + * Netdevice notifier + +PM notifier error injection module +---------------------------------- +This feature is controlled through debugfs interface +/sys/kernel/debug/notifier-error-inject/pm/actions/<notifier event>/error + +Possible PM notifier events to be failed are: + + * PM_HIBERNATION_PREPARE + * PM_SUSPEND_PREPARE + * PM_RESTORE_PREPARE + +Example: Inject PM suspend error (-12 = -ENOMEM) + + # cd /sys/kernel/debug/notifier-error-inject/pm/ + # echo -12 > actions/PM_SUSPEND_PREPARE/error + # echo mem > /sys/power/state + bash: echo: write error: Cannot allocate memory + +Memory hotplug notifier error injection module +---------------------------------------------- +This feature is controlled through debugfs interface +/sys/kernel/debug/notifier-error-inject/memory/actions/<notifier event>/error + +Possible memory notifier events to be failed are: + + * MEM_GOING_ONLINE + * MEM_GOING_OFFLINE + +Example: Inject memory hotplug offline error (-12 == -ENOMEM) + + # cd /sys/kernel/debug/notifier-error-inject/memory + # echo -12 > actions/MEM_GOING_OFFLINE/error + # echo offline > /sys/devices/system/memory/memoryXXX/state + bash: echo: write error: Cannot allocate memory + +powerpc pSeries reconfig notifier error injection module +-------------------------------------------------------- +This feature is controlled through debugfs interface +/sys/kernel/debug/notifier-error-inject/pSeries-reconfig/actions/<notifier event>/error + +Possible pSeries reconfig notifier events to be failed are: + + * PSERIES_RECONFIG_ADD + * PSERIES_RECONFIG_REMOVE + * PSERIES_DRCONF_MEM_ADD + * PSERIES_DRCONF_MEM_REMOVE + +Netdevice notifier error injection module +---------------------------------------------- +This feature is controlled through debugfs interface +/sys/kernel/debug/notifier-error-inject/netdev/actions/<notifier event>/error + +Netdevice notifier events which can be failed are: + + * NETDEV_REGISTER + * NETDEV_CHANGEMTU + * NETDEV_CHANGENAME + * NETDEV_PRE_UP + * NETDEV_PRE_TYPE_CHANGE + * NETDEV_POST_INIT + * NETDEV_PRECHANGEMTU + * NETDEV_PRECHANGEUPPER + * NETDEV_CHANGEUPPER + +Example: Inject netdevice mtu change error (-22 == -EINVAL) + + # cd /sys/kernel/debug/notifier-error-inject/netdev + # echo -22 > actions/NETDEV_CHANGEMTU/error + # ip link set eth0 mtu 1024 + RTNETLINK answers: Invalid argument + +For more usage examples +----------------------- +There are tools/testing/selftests using the notifier error injection features +for CPU and memory notifiers. + + * tools/testing/selftests/cpu-hotplug/on-off-test.sh + * tools/testing/selftests/memory-hotplug/on-off-test.sh + +These scripts first do simple online and offline tests and then do fault +injection tests if notifier error injection module is available. diff --git a/Documentation/fault-injection/nvme-fault-injection.txt b/Documentation/fault-injection/nvme-fault-injection.txt new file mode 100644 index 000000000..8fbf3bf60 --- /dev/null +++ b/Documentation/fault-injection/nvme-fault-injection.txt @@ -0,0 +1,116 @@ +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 diff --git a/Documentation/fault-injection/provoke-crashes.txt b/Documentation/fault-injection/provoke-crashes.txt new file mode 100644 index 000000000..7a9d3d815 --- /dev/null +++ b/Documentation/fault-injection/provoke-crashes.txt @@ -0,0 +1,38 @@ +The lkdtm module provides an interface to crash or injure the kernel at +predefined crashpoints to evaluate the reliability of crash dumps obtained +using different dumping solutions. The module uses KPROBEs to instrument +crashing points, but can also crash the kernel directly without KRPOBE +support. + + +You can provide the way either through module arguments when inserting +the module, or through a debugfs interface. + +Usage: insmod lkdtm.ko [recur_count={>0}] cpoint_name=<> cpoint_type=<> + [cpoint_count={>0}] + + recur_count : Recursion level for the stack overflow test. Default is 10. + + cpoint_name : Crash point where the kernel is to be crashed. It can be + one of INT_HARDWARE_ENTRY, INT_HW_IRQ_EN, INT_TASKLET_ENTRY, + FS_DEVRW, MEM_SWAPOUT, TIMERADD, SCSI_DISPATCH_CMD, + IDE_CORE_CP, DIRECT + + cpoint_type : Indicates the action to be taken on hitting the crash point. + It can be one of PANIC, BUG, EXCEPTION, LOOP, OVERFLOW, + CORRUPT_STACK, UNALIGNED_LOAD_STORE_WRITE, OVERWRITE_ALLOCATION, + WRITE_AFTER_FREE, + + cpoint_count : Indicates the number of times the crash point is to be hit + to trigger an action. The default is 10. + +You can also induce failures by mounting debugfs and writing the type to +<mountpoint>/provoke-crash/<crashpoint>. E.g., + + mount -t debugfs debugfs /mnt + echo EXCEPTION > /mnt/provoke-crash/INT_HARDWARE_ENTRY + + +A special file is `DIRECT' which will induce the crash directly without +KPROBE instrumentation. This mode is the only one available when the module +is built on a kernel without KPROBEs support. |