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Add default stack checking 

When your kernel is built with kernel stack tracing enabled and you
have the debugfs filesystem mounted.  Then the zfs.sh script will clear
the worst observed kernel stack depth on module load and check the worst
case usage on module removal.  If the stack depth ever exceeds 7000
bytes the full stack will be printed for debugging.  This is dangerously
close to overrunning the default 8k stack.

This additional advisory debugging is particularly valuable when running
the regression tests on a kernel built with 16k stacks.  In this case,
almost no matter how bad the stack overrun is you will see be able to
get a clean stack trace for debugging.  Since the worst case stack usage
can be highly variable it's helpful to always check the worst case usage.
This commit is contained in:
Brian Behlendorf 2011-06-11 22:48:49 -07:00
parent da88a7fbe8
commit 10715a0187
2 changed files with 28 additions and 0 deletions
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26
scripts/common.sh.in
View File

@ -635,3 +635,29 @@ wait_udev() {
return 0 return 0
} }
stack_clear() {
local STACK_MAX_SIZE=/sys/kernel/debug/tracing/stack_max_size
local STACK_TRACER_ENABLED=/proc/sys/kernel/stack_tracer_enabled
if [ -e $STACK_MAX_SIZE ]; then
echo 1 >$STACK_TRACER_ENABLED
echo 0 >$STACK_MAX_SIZE
fi
}
stack_check() {
local STACK_MAX_SIZE=/sys/kernel/debug/tracing/stack_max_size
local STACK_TRACE=/sys/kernel/debug/tracing/stack_trace
local STACK_LIMIT=7000
if [ -e $STACK_MAX_SIZE ]; then
STACK_SIZE=`cat $STACK_MAX_SIZE`
if [ $STACK_SIZE -ge $STACK_LIMIT ]; then
echo
echo "Warning: max stack size $STACK_SIZE bytes"
cat $STACK_TRACE
fi
fi
}

2
scripts/zfs.sh
View File

@ -66,8 +66,10 @@ fi
if [ ${UNLOAD} ]; then if [ ${UNLOAD} ]; then
umount -t zfs -a umount -t zfs -a
stack_check
unload_modules unload_modules
else else
stack_clear
check_modules || die "${ERROR}" check_modules || die "${ERROR}"
load_modules "$@" load_modules "$@"
wait_udev /dev/zfs 30 wait_udev /dev/zfs 30