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Re: [Qemu-devel] [PATCH] tests: set MALLOC_PERTURB_ to expose memory bug
Re: [Qemu-devel] [PATCH] tests: set MALLOC_PERTURB_ to expose memory bugs
Fri, 17 May 2013 13:15:52 +0200
On Fri, May 17, 2013 at 11:54 AM, Markus Armbruster <address@hidden> wrote:
> Stefan Hajnoczi <address@hidden> writes:
>> glibc wipes malloc(3) memory when the MALLOC_PERTURB_ environment
>> variable is set. The value of the environment variable determines the
>> bit pattern used to wipe memory. For more information, see
>> Set MALLOC_PERTURB_ for gtester and qemu-iotests. Note we always set
>> the environment variable to 1 so the test is deterministic. Setting a
>> random variable might expose more bugs but would be harder to reproduce.
>> Both make check and qemu-iotests pass with MALLOC_PERTURB_ enabled.
>> Signed-off-by: Stefan Hajnoczi <address@hidden>
>> Lucas noticed KVM autotest failures when enabling MALLOC_PERTURB_. By
>> it for in-tree test suites we can detect memory management errors earlier.
>> tests/Makefile | 4 +++-
>> tests/qemu-iotests/check | 2 +-
>> 2 files changed, 4 insertions(+), 2 deletions(-)
>> diff --git a/tests/Makefile b/tests/Makefile
>> index a307d5a..25f6d28 100644
>> --- a/tests/Makefile
>> +++ b/tests/Makefile
>> @@ -171,6 +171,7 @@ GCOV_OPTIONS = -n $(if $(V),-f,)
>> $(patsubst %, check-qtest-%, $(QTEST_TARGETS)): check-qtest-%:
>> $(if $(CONFIG_GCOV),@rm -f *.gcda */*.gcda */*/*.gcda */*/*/*.gcda,)
>> $(call quiet-command,QTEST_QEMU_BINARY=$*-softmmu/qemu-system-$* \
>> + MALLOC_PERTURB_=1 \
>> gtester $(GTESTER_OPTIONS) -m=$(SPEED)
>> $(check-qtest-$*-y),"GTESTER $@")
>> $(if $(CONFIG_GCOV),@for f in $(gcov-files-$*-y); do \
>> echo Gcov report for $$f:;\
> If you want punishment, why not go for extra punishment?
> MALLOC_PERTURB_=$(($RANDOM % 255 + 1))
Covered in the commit description:
"Note we always set
the environment variable to 1 so the test is deterministic. Setting a
random variable might expose more bugs but would be harder to reproduce."
I didn't want to clutter output with "MALLOC_PERTURB_=123" on every
run. AFAIK we have no log where this can be silently stashed. I
guess we could write it to a file and add that to .gitignore.