Since I reported this issue I have tried to debug this problem and found that the function call to 'i8k_get_fn_status' in the kernel module 'dell-smm-hwmon' (code at https://github.com/torvalds/linux/blob/master/drivers/hwmon/dell-smm-hwmon.c) is what causes low memory corruption on Dell Inspiron 3847.
This affects the procfs '/proc/i8k' interface only when kernel compiled with 'CONFIG_I8K' I have downloaded kernel module from https://github.com/torvalds/linux/blob/master/drivers/hwmon/dell-smm-hwmon.c and modified/compiled to debug/test this issue with possible fixes. A possible fix involves disallowing 'i8k_get_fn_status' calls for affected machines using a blacklist. I have attached modified kernel module code and makefile used as well as script and script output to check problem once modified module is loaded. Attachments: dell-smm-hwmon.c Makefile low_mem_corruption.sh script_output.txt I suspect this issue may affect other Dell machines (not just Inspiron 3847) ?? (see https://bugs.launchpad.net/i8kutils/+bug/1179282/comments/41) During the process of figuring out the likely problem I have found that the Dell SMM/BIOS seems to be buggy on various machines! Testing of modified module has been done under Ubuntu 18.04.1 LTS 4.15.0-29-generic, and 4.15.0-33-generic kernels and Linux Mint Tara 19 (4.15.0-29-generic, 4.15.0-33-generic kernels) and Linux Mint Tara 17.3 (4.4.0-134-generic, old 3.19.0-32-generic kernel) Output of tests in in attached file 'script_output.txt'. The low memory corruption problem can be reproduced on the Dell Inspiron 3847 running: Ubuntu 18.04.1 LTS, 4.15.0-32-generic Ubuntu 18.04.1 LTS, 4.15.0-33-generic Ubuntu 18.04.1 LTS, 4.19-rc1 upstream kernel (4.19.0-041900rc1) Linux Mint 19 Tara, 4.15.0-32-generic Linux Mint 19 Tara, 4.15.0-33-generic Linux Mint 17.3, OLD 3.19.0-32-generic kernel Linux Mint 17.3, 4.4.0-134-generic kernel Low memory corruption problem DOES NOT OCCUR on: Ubuntu 18.04.1 LTS, 4.15.0-29-generic Ubuntu 18.04.1 LTS, 4.15.0-30-generic Linux Mint 19 Tara, 4.15.0-29-generic I have no idea why there is different behaviour running under the different kernels noted above. Does this imply the problem may be in changes to the kernel? I am new to kernel modules and this is my first attempt at debugging one but I hope the info here is useful in fixing the problem and can be passed on to the maintainer. from https://github.com/torvalds/linux/blob/master/MAINTAINERS DELL LAPTOP SMM DRIVER M: Pali Rohár <[email protected]> S: Maintained F: drivers/hwmon/dell-smm-hwmon.c ** Attachment added: "script_output.txt" https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1789519/+attachment/5185074/+files/script_output.txt -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1789519 Title: Low Memory corruption logged in syslog To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1789519/+subscriptions -- ubuntu-bugs mailing list [email protected] https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
