On Fri, 14 Aug 2020 at 18:11, Steven Rostedt <rostedt@xxxxxxxxxxx> wrote:
>
> On Fri, 14 Aug 2020 14:53:36 +0530
> Naresh Kamboju <naresh.kamboju@xxxxxxxxxx> wrote:
>
> > steps to reproduce:
> > # Boot qemu arm64 with trace configs enabled ^.
> > # cd /opt/ltp
> > # ./runltp -f tracing
>
> I don't run ltp, what exactly is this doing?
LTP running ftrace stress testing
Test case :
------------
LOOP=200
# Use up to 10% of free memory
free_mem=`cat /proc/meminfo | grep '^MemFree' | awk '{ print $2 }'`
cpus=`tst_ncpus`
step=$(( $free_mem / 10 / $LOOP / $cpus ))
if [ $step -eq 0 ]; then
step=1
LOOP=50
fi
while true; do
new_size=1
i=0
while [ $i -lt $LOOP ]; do
echo $new_size > "$TRACING_PATH"/buffer_size_kb ----> Test
got failed here
new_size=$(( $new_size + $step ))
i=$((i + 1))
done
i=0
while [ $i -lt $LOOP ]; do
new_size=$(( $new_size - $step ))
echo $new_size > "$TRACING_PATH"/buffer_size_kb
i=$((i + 1))
done
sleep 1
done
test case link,
https://raw.githubusercontent.com/linux-test-project/ltp/master/testcases/kernel/tracing/ftrace_test/ftrace_stress/ftrace_buffer_size_kb.sh
ftrace_buffer_size_kb.sh: line 33: echo: write error: Cannot allocate memory
ftrace_buffer_size_kb.sh: line 33: echo: write error: Cannot allocate memory
ftrace_buffer_size_kb.sh: line 33: echo: write error: Cannot allocate memory
ftrace_buffer_size_kb.sh: line 33: echo: write error: Cannot allocate memory
ftrace_buffer_size_kb.sh: line 33: echo: write error: Cannot allocate memory
[ 90.729590] ------------[ cut here ]------------
[ 90.729882] WARNING: CPU: 1 PID: 2840 at
kernel/trace/ring_buffer.c:1273 rb_set_head_page+0x7c/0x108
[ 90.733593] Modules linked in: rfkill snd_soc_hdmi_codec
crct10dif_ce adv7511 cec qcom_spmi_temp_alarm rtc_pm8xxx msm
snd_soc_msm8916_analog qcom_camss mdt_loader videobuf2_dma_sg
v4l2_fwnode videobuf2_memops snd_soc_lpass_apq8016 i2c_qcom_cci
drm_kms_helper snd_soc_lpass_cpu qcom_rng snd_soc_msm8916_digital
videobuf2_v4l2 snd_soc_lpass_platform snd_soc_apq8016_sbc
snd_soc_qcom_common videobuf2_common qrtr ns socinfo display_connector
drm rmtfs_mem fuse
[ 90.761426] CPU: 1 PID: 2840 Comm: cat Not tainted 5.8.0-next-20200814 #1
[ 90.782653] Hardware name: Qualcomm Technologies, Inc. APQ 8016 SBC (DT)
[ 90.789423] pstate: 60000085 (nZCv daIf -PAN -UAO BTYPE=--)
[ 90.796165] pc : rb_set_head_page+0x7c/0x108
[ 90.801416] lr : rb_per_cpu_empty+0x18/0x88
[ 90.805922] sp : ffff80001673bc30
File and line number:
kernel/trace/ring_buffer.c:1273 rb_set_head_page
static struct buffer_page *
rb_set_head_page(struct ring_buffer_per_cpu *cpu_buffer)
{
struct buffer_page *head;
struct buffer_page *page;
struct list_head *list;
int i;
if (RB_WARN_ON(cpu_buffer, !cpu_buffer->head_page))
return NULL;
/* sanity check */
list = cpu_buffer->pages;
if (RB_WARN_ON(cpu_buffer, rb_list_head(list->prev->next) != list))
return NULL;
page = head = cpu_buffer->head_page;
/*
* It is possible that the writer moves the header behind
* where we started, and we miss in one loop.
* A second loop should grab the header, but we'll do
* three loops just because I'm paranoid.
*/
for (i = 0; i < 3; i++) {
do {
if (rb_is_head_page(cpu_buffer, page, page->list.prev)) {
cpu_buffer->head_page = page;
return page;
}
rb_inc_page(cpu_buffer, &page);
} while (page != head);
}
RB_WARN_ON(cpu_buffer, 1); ---> pointing this link number 1273
Full test case output and kernel warning,
https://qa-reports.linaro.org/lkft/linux-next-oe/build/next-20200814/testrun/3066187/suite/linux-log-parser/test/check-kernel-bug-1668287/log
- Naresh Kamboju
>
> -- Steve
