FYI, we noticed the following commit (built with gcc-6): commit: 3416099d53d9593ab1d374180e9cd2a71fa2f4d5 ("net: Refactor XPS for CPUs and Rx queues") url: https://github.com/0day-ci/linux/commits/Amritha-Nambiar/net-Refactor-XPS-for-CPUs-and-Rx-queues/20180518-053915 in testcase: boot on test machine: qemu-system-x86_64 -enable-kvm -smp 2 -m 512M caused below changes (please refer to attached dmesg/kmsg for entire log/backtrace): +--------------------------------------------------------------------+------------+------------+ | | b9f672af14 | 3416099d53 | +--------------------------------------------------------------------+------------+------------+ | boot_successes | 0 | 0 | | boot_failures | 8 | 8 | | WARNING:at_lib/debugobjects.c:#__debug_object_init | 8 | 8 | | RIP:__debug_object_init | 8 | 8 | | WARNING:suspicious_RCU_usage | 8 | 8 | | lib/test_rhashtable.c:#suspicious_rcu_dereference_protected()usage | 8 | 8 | | net/core/dev.c:#suspicious_rcu_dereference_protected()usage | 0 | 4 | +--------------------------------------------------------------------+------------+------------+ [ 26.138522] WARNING: suspicious RCU usage [ 26.139128] 4.17.0-rc4-01248-g3416099 #1 Tainted: G W [ 26.140140] ----------------------------- [ 26.140727] net/core/dev.c:2260 suspicious rcu_dereference_protected() usage! [ 26.142028] [ 26.142028] other info that might help us debug this: [ 26.142028] [ 26.143388] [ 26.143388] rcu_scheduler_active = 2, debug_locks = 1 [ 26.144263] 3 locks held by netifd/973: [ 26.144830] #0: (ptrval) (sb_writers#4){.+.+}, at: vfs_write+0xcd/0x1b0 [ 26.145825] #1: (ptrval) (&of->mutex){+.+.}, at: kernfs_fop_write+0xb1/0x170 [ 26.146930] #2: (ptrval) (kn->count#17){.+.+}, at: kernfs_fop_write+0xba/0x170 [ 26.148084] [ 26.148084] stack backtrace: [ 26.148655] CPU: 1 PID: 973 Comm: netifd Tainted: G W 4.17.0-rc4-01248-g3416099 #1 [ 26.149799] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.10.2-1 04/01/2014 [ 26.150951] Call Trace: [ 26.151288] dump_stack+0xb0/0x10b [ 26.151741] __netif_set_xps_queue+0x1cb/0xc00 [ 26.152350] ? __bitmap_parse+0x14d/0x1c0 [ 26.152938] xps_cpus_store+0x9f/0xe0 [ 26.153421] kernfs_fop_write+0xf0/0x170 [ 26.153947] __vfs_write+0x33/0x140 [ 26.154410] ? rcu_read_lock_sched_held+0x5f/0x90 [ 26.155123] ? rcu_sync_lockdep_assert+0x28/0x50 [ 26.155744] ? __sb_start_write+0x14e/0x1c0 [ 26.156310] ? vfs_write+0xcd/0x1b0 [ 26.156783] vfs_write+0xdf/0x1b0 [ 26.157247] ksys_write+0x55/0xc0 [ 26.157699] do_int80_syscall_32+0x73/0x220 [ 26.158264] entry_INT80_compat+0x71/0x80 [ 26.165010] IPv6: ADDRCONF(NETDEV_UP): eth0: link is not ready [ 26.167173] 8021q: adding VLAN 0 to HW filter on device eth0 LKP: HOSTNAME vm-lkp-nex04-openwrt-ia32-19, MAC , kernel 4.17.0-rc4-01248-g3416099 1, serial console /dev/ttyS0 [ 27.410153] Kernel tests: Boot OK! [ 27.410153] LKP: waiting for network... [ 28.230718] e1000: eth0 NIC Link is Up 1000 Mbps Full Duplex, Flow Control: RX [ 28.233430] IPv6: ADDRCONF(NETDEV_CHANGE): eth0: link becomes ready [ 29.430135] /lkp/lkp/src/bin/run-lkp [ 29.430135] RESULT_ROOT=/result/boot/1/vm-lkp-nex04-openwrt-ia32/openwrt-i386-2016-03-16.cgz/x86_64-randconfig-s1-05191730/gcc-6/3416099d53d9593ab1d374180e9cd2a71fa2f4d5/0 [ 29.430135] job=/lkp/scheduled/vm-lkp-nex04-openwrt-ia32-19/boot-1-openwrt-i386-2016-03-16.cgz-3416099d53d9593ab1d374180e9cd2a71fa2f4d5-20180519-65944-14mjjk6-0.yaml [ 29.430135] run-job /lkp/scheduled/vm-lkp-nex04-openwrt-ia32-19/boot-1-openwrt-i386-2016-03-16.cgz-3416099d53d9593ab1d374180e9cd2a71fa2f4d5-20180519-65944-14mjjk6-0.yaml [ 29.430135] /bin/busybox wget -q http://inn:80/~lkp/cgi-bin/lkp-jobfile-append-var?job_file=/lkp/scheduled/vm-lkp-nex04-openwrt-ia32-19/boot-1-openwrt-i386-2016-03-16.cgz-3416099d53d9593ab1d374180e9cd2a71fa2f4d5-20180519-65944-14mjjk6-0.yaml&job_state=running -O /dev/null [ 29.430135] skip microcode check for virtual machine [ 31.470090] /bin/busybox wget -q http://inn:80/~lkp/cgi-bin/lkp-jobfile-append-var?job_file=/lkp/scheduled/vm-lkp-nex04-openwrt-ia32-19/boot-1-openwrt-i386-2016-03-16.cgz-3416099d53d9593ab1d374180e9cd2a71fa2f4d5-20180519-65944-14mjjk6-0.yaml&job_state=post_run -O /dev/null [ 32.679099] cat (1334) used greatest stack depth: 13344 bytes left [ 33.490117] kill 1334 cat /proc/kmsg [ 33.490117] wait for background monitors: 1344 oom-killer [ 35.264972] sysrq: SysRq : Emergency Sync [ 35.266203] sysrq: SysRq : Resetting [ 35 Elapsed time: 40 #!/bin/bash # To reproduce, # 1) save job-script and this script (both are attached in 0day report email) # 2) run this script with your compiled kernel and optional env $INSTALL_MOD_PATH kernel=$1 initrds=( /osimage/openwrt/openwrt-i386-2016-03-16.cgz /lkp/lkp/lkp-i386.cgz ) HTTP_PREFIX=https://github.com/0day-ci/lkp-qemu/raw/master wget --timestamping "${initrds[@]/#/$HTTP_PREFIX}" { cat "${initrds[@]//*\//}" [[ $INSTALL_MOD_PATH ]] && ( cd "$INSTALL_MOD_PATH" find lib | cpio -o -H newc --quiet | gzip ) echo job-script | cpio -o -H newc --quiet | gzip } > initrd.img kvm=( qemu-system-x86_64 -enable-kvm -kernel $kernel -initrd initrd.img -m 512 -smp 2 -device e1000,netdev=net0 -netdev user,id=net0,hostfwd=tcp::23288-:22 -boot order=nc -no-reboot -watchdog i6300esb -watchdog-action debug -rtc base=localtime -serial stdio -display none -monitor null ) append=( ip=::::vm-lkp-nex04-openwrt-ia32-19::dhcp root=/dev/ram0 To reproduce: git clone https://github.com/intel/lkp-tests.git cd lkp-tests bin/lkp qemu -k job-script # job-script is attached in this email Thanks, Xiaolong