Hi Christophe Leroy and gpio experts,
Greeting!
Platform: Tigerlake-H and so on x86 platforms
All detailed info is in link: https://github.com/xupengfe/syzkaller_logs/tree/main/issue_bisect/230406_gpi... Bisect info: https://github.com/xupengfe/syzkaller_logs/blob/main/issue_bisect/230406_gpi...
gpio-mockup.sh kslef-test failed in v6.3-rc5 kernel. gpio-mockup.sh(gpio overflow test) in kself-test could reproduce this issue: cd linux/tools/testing/selftests 1. ./kselftest_install.sh 2. cd linux/tools/testing/selftests/kselftest_install/gpio # ./gpio-mockup.sh 1. Module load tests 1.1. dynamic allocation of gpio 2. Module load error tests 2.1 gpio overflow test failed: unexpected chip - gpiochip1 GPIO gpio-mockup test FAIL
And the simplified steps to reproduce this issue are as follow: " # Load gpio_mockup with overflow ranges -1,1024: modprobe -q gpio_mockup gpio_mockup_ranges="-1,1024"
# Check is there some Call Trace generated in dmesg dmesg | grep -C 5 Call
# Should not generate any gpiochip folder like /sys/kernel/debug/gpio-mockup/gpiochip1 # Because load gpio_mockup with overflow ranges -1,1024 find "/sys/kernel/debug/gpio-mockup/" -name gpiochip* -type d | sort
# Unload the gpio_mockup module modprobe -r gpio_mockup # Check is there "Call Trace" generated in dmesg dmesg | grep -C 5 Call "
Actually the judgement "gpio-mockup.sh" test/bisect judgement point is that: Should not generate any gpiochip folder like /sys/kernel/debug/gpio-mockup/gpiochip1 after load gpio_mockup with overflow ranges -1,1024.
I met gpio-mockup.sh test failed but there is no any "Call Trace" dmesg info sometimes.
So the shortest check steps are as follow: " 1. modprobe -q gpio_mockup gpio_mockup_ranges="-1,1024" After above gpio_mockup module loaded with overflow range "-1,1024": Correct behavior as previous v6.1 or older kernel:"gpio should not load "gpiochip1" due to overflow range -1,1024"; Wrong behavior in v6.3-rc5 kernel: "gpio *load* "gpiochip1" with overflow range -1,1024 and "gpiochip1" should not be loaded". The underlying problem was already buried here.
2. Could use below command to check if "gpiochip1" generated: As before v6.1, there was no "/sys/kernel/debug/gpio-mockup/gpiochip1" sysfs folder due to overflow range -1,1024"; Wrong behavior in v6.3-rc5 kernel: "/sys/kernel/debug/gpio-mockup/gpiochip1" sysfs folder generated as follow command check: # find "/sys/kernel/debug/gpio-mockup/" -name gpiochip* -type d | sort /sys/kernel/debug/gpio-mockup/gpiochip1 If there is gpiochip* generated, gpio-mockup.sh kself-test would be failed also. "
Bisected and found the bad commit was: " 7b61212f2a07a5afd213c8876e52b5c9946441e2 gpiolib: Get rid of ARCH_NR_GPIOS " And after reverted the above commit on top of v6.3-rc5 kernel, above gpio-mockup.sh kself-test could pass and this issue was gone.
Now gpio-mockup.sh kself-test is failed on almost all x86 platform from v6.2 cycle mainline kernel.
I hope above info is helpful to solve the "gpio-mockup.sh kself-test failed" problem.
Thanks! BR.