Subject: [fs] ef30fb3c60: kernel write not supported for file /sys/kernel/softlockup_panic

From: kernel test robot <[email-masked]>
Date: Tue, 1 Sep 2020 14:48:49 +0800

Greeting,

FYI, we noticed the following commit (built with gcc-9):

commit: ef30fb3c6024456f0bb0eaf2f3e12eaf6b3d64a8 ("[PATCH 01/10] fs: don't allow kernel reads and writes without iter ops")
url: https://github.com/0day-ci/linux/commits/Christoph-Hellwig/fs-don-t-allow-kernel-reads-and-writes-without-iter-ops/20200828-000108
base: https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git 15bc20c6af4ceee97a1f90b43c0e386643c071b4

in testcase: suspend-stress
with following parameters:

	mode: freeze
	iterations: 10

on test machine: 4 threads Ivy Bridge with 4G memory

caused below changes (please refer to attached dmesg/kmsg for entire log/backtrace):

If you fix the issue, kindly add following tag
Reported-by: kernel test robot <[email-masked]>

kern  :info  : [   30.304228] Freeing unused decrypted memory: 2040K
kern  :info  : [   30.304752] Freeing unused kernel image (initmem) memory: 2428K
kern  :info  : [   30.313588] Write protecting the kernel read-only data: 22528k
kern  :info  : [   30.314303] Freeing unused kernel image (text/rodata gap) memory: 2040K
kern  :info  : [   30.314778] Freeing unused kernel image (rodata/data gap) memory: 1356K
kern  :warn  : [   30.315092] kernel write not supported for file /sys/kernel/softlockup_panic (pid: 1 comm: swapper/0)
kern  :err   : [   30.315384] Failed to set sysctl parameter 'kernel.softlockup_panic=1': invalid value
kern  :info  : [   30.322606] Run /init as init process
kern  :debug : [   30.322778]   with arguments:
kern  :debug : [   30.322925]     /init
kern  :debug : [   30.323058]     nokaslr
kern  :debug : [   30.323194]   with environment:
kern  :debug : [   30.323344]     HOME=/
kern  :debug : [   30.323480]     TERM=linux
kern  :debug : [   30.323630]     BOOT_IMAGE=/pkg/linux/x86_64-rhel-8.3/gcc-9/ef30fb3c6024456f0bb0eaf2f3e12eaf6b3d64a8/vmlinuz-5.9.0-rc2-00097-gef30fb3c602445
kern  :debug : [   30.324011]     user=lkp
kern  :debug : [   30.324151]     job=/lkp/jobs/scheduled/lkp-ivb-toshiba1/suspend-stress-10-freeze-debian-x86_64-20180403.cgz-ef30fb3c6024456f0bb0eaf2f3e12eaf6b3d64a8-20200830-19491-9yjnlj-1.yaml
kern  :debug : [   30.324633]     ARCH=x86_64
kern  :debug : [   30.324778]     kconfig=x86_64-rhel-8.3
kern  :debug : [   30.324942]     branch=linux-review/Christoph-Hellwig/fs-don-t-allow-kernel-reads-and-writes-without-iter-ops/20200828-000108
kern  :debug : [   30.325289]     commit=ef30fb3c6024456f0bb0eaf2f3e12eaf6b3d64a8
kern  :debug : [   30.325491]     max_uptime=3600
kern  :debug : [   30.325647]     RESULT_ROOT=/result/suspend-stress/10-freeze/lkp-ivb-toshiba1/debian-x86_64-20180403.cgz/x86_64-rhel-8.3/gcc-9/ef30fb3c6024456f0bb0eaf2f3e12eaf6b3d64a8/3
kern  :debug : [   30.326096]     LKP_SERVER=inn
kern  :debug : [   30.326239]     softlockup_panic=1
kern  :debug : [   30.326388]     prompt_ramdisk=0
kern  :debug : [   30.326533]     vga=normal

To reproduce:

        git clone https://github.com/intel/lkp-tests.git
        cd lkp-tests
        bin/lkp install job.yaml  # job file is attached in this email
        bin/lkp run     job.yaml

Thanks,
Rong Chen