yardstick -

Age	Commit message (Expand)	Author	Files	Lines
2017-02-17	Update missing license headers	Deepak S	1	-0/+8
2016-07-05	SFC Yardstick test	Manuel Buil	1	-0/+50

Fault injection capabilities infrastructure =========================================== See also drivers/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 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. 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> 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 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