329409aeda
This patch provides stacktrace filtering feature. The stacktrace filter allows failing only for the caller you are interested in. For example someone may want to inject kmalloc() failures into only e100 module. they want to inject not only direct kmalloc() call, but also indirect allocation, too. - e100_poll --> netif_receive_skb --> packet_rcv_spkt --> skb_clone --> kmem_cache_alloc This patch enables to detect function calls like this by stacktrace and inject failures. The script Documentaion/fault-injection/failmodule.sh helps it. The range of text section of loaded e100 is expected to be [/sys/module/e100/sections/.text, /sys/module/e100/sections/.exit.text) So failmodule.sh stores these values into /debug/failslab/address-start and /debug/failslab/address-end. The maximum stacktrace depth is specified by /debug/failslab/stacktrace-depth. Please see the example that demonstrates how to inject slab allocation failures only for a specific module in Documentation/fault-injection/fault-injection.txt [dwm@meer.net: reject failure if any caller lies within specified range] Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com> Signed-off-by: Don Mullis <dwm@meer.net> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
226 lines
5.7 KiB
Plaintext
226 lines
5.7 KiB
Plaintext
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_make_request
|
|
|
|
injects disk IO errors on permitted devices by
|
|
/sys/block/<device>/make-it-fail or
|
|
/sys/block/<device>/<partition>/make-it-fail. (generic_make_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.
|
|
|
|
- /debug/*/probability:
|
|
|
|
likelihood of failure injection, in percent.
|
|
Format: <percent>
|
|
|
|
Note that one-failure-per-handred is a very high error rate
|
|
for some testcases. Please set probably=100 and configure
|
|
/debug/*/interval for such testcases.
|
|
|
|
- /debug/*/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.
|
|
|
|
- /debug/*/times:
|
|
|
|
specifies how many times failures may happen at most.
|
|
A value of -1 means "no limit".
|
|
|
|
- /debug/*/space:
|
|
|
|
specifies an initial resource "budget", decremented by "size"
|
|
on each call to should_fail(,size). Failure injection is
|
|
suppressed until "space" reaches zero.
|
|
|
|
- /debug/*/verbose
|
|
|
|
Format: { 0 | 1 | 2 }
|
|
specifies the verbosity of the messages when failure is injected.
|
|
We default to 0 (no extra messages), setting it to '1' will
|
|
print only to tell failure happened, '2' will print call trace too -
|
|
it is useful to debug the problems revealed by fault injection
|
|
capabilities.
|
|
|
|
- /debug/*/task-filter:
|
|
|
|
Format: { 0 | 1 }
|
|
A value of '0' disables filtering by process (default).
|
|
Any positive value limits failures to only processes indicated by
|
|
/proc/<pid>/make-it-fail==1.
|
|
|
|
- /debug/*/require-start:
|
|
- /debug/*/require-end:
|
|
- /debug/*/reject-start:
|
|
- /debug/*/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).
|
|
|
|
- /debug/*/stacktrace-depth:
|
|
|
|
specifies the maximum stacktrace depth walked during search
|
|
for a caller within [address-start,address-end).
|
|
|
|
- /debug/fail_page_alloc/ignore-gfp-highmem:
|
|
|
|
Format: { 0 | 1 }
|
|
default is 0, setting it to '1' won't inject failures into
|
|
highmem/user allocations.
|
|
|
|
- /debug/failslab/ignore-gfp-wait:
|
|
- /debug/fail_page_alloc/ignore-gfp-wait:
|
|
|
|
Format: { 0 | 1 }
|
|
default is 0, setting it to '1' will inject failures
|
|
only into non-sleep allocations (GFP_ATOMIC allocations).
|
|
|
|
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=<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 the 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.
|
|
There is a helper function for it.
|
|
|
|
init_fault_attr_entries(entries, attr, name);
|
|
void cleanup_fault_attr_entries(entries);
|
|
|
|
- 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
|
|
|
|
should_fail() returns 1 when failures should happen.
|
|
|
|
should_fail(attr,size);
|
|
|
|
Application Examples
|
|
--------------------
|
|
|
|
o inject slab allocation failures into module init/cleanup code
|
|
|
|
------------------------------------------------------------------------------
|
|
#!/bin/bash
|
|
|
|
FAILCMD=Documentation/fault-injection/failcmd.sh
|
|
BLACKLIST="root_plug evbug"
|
|
|
|
FAILNAME=failslab
|
|
echo Y > /debug/$FAILNAME/task-filter
|
|
echo 10 > /debug/$FAILNAME/probability
|
|
echo 100 > /debug/$FAILNAME/interval
|
|
echo -1 > /debug/$FAILNAME/times
|
|
echo 2 > /debug/$FAILNAME/verbose
|
|
echo 1 > /debug/$FAILNAME/ignore-gfp-wait
|
|
|
|
blacklist()
|
|
{
|
|
echo $BLACKLIST | grep $1 > /dev/null 2>&1
|
|
}
|
|
|
|
oops()
|
|
{
|
|
dmesg | grep BUG > /dev/null 2>&1
|
|
}
|
|
|
|
find /lib/modules/`uname -r` -name '*.ko' -exec basename {} .ko \; |
|
|
while read i
|
|
do
|
|
oops && exit 1
|
|
|
|
if ! blacklist $i
|
|
then
|
|
echo inserting $i...
|
|
bash $FAILCMD modprobe $i
|
|
fi
|
|
done
|
|
|
|
lsmod | awk '{ if ($3 == 0) { print $1 } }' |
|
|
while read i
|
|
do
|
|
oops && exit 1
|
|
|
|
if ! blacklist $i
|
|
then
|
|
echo removing $i...
|
|
bash $FAILCMD modprobe -r $i
|
|
fi
|
|
done
|
|
|
|
------------------------------------------------------------------------------
|
|
|
|
o inject slab allocation failures only for a specific module
|
|
|
|
------------------------------------------------------------------------------
|
|
#!/bin/bash
|
|
|
|
FAILMOD=Documentation/fault-injection/failmodule.sh
|
|
|
|
echo injecting errors into the module $1...
|
|
|
|
modprobe $1
|
|
bash $FAILMOD failslab $1 10
|
|
echo 25 > /debug/failslab/probability
|
|
|
|
------------------------------------------------------------------------------
|
|
|