FYI, we noticed the following commit: commit: f2cb13609d5397cdd747f3ed6fb651233851717d ("sched/topology: Split out scheduler topology code from core.c into topology.c") https://git.kernel.org/cgit/linux/kernel/git/tip/tip.git sched/core in testcase: boot on test machine: qemu-system-i386 -enable-kvm -m 360M caused below changes (please refer to attached dmesg/kmsg for entire log/backtrace): +---------------------------+------------+------------+ | | 004172bdad | f2cb13609d | +---------------------------+------------+------------+ | boot_successes | 8 | 4 | | boot_failures | 0 | 4 | | BUG:workqueue_lockup-pool | 0 | 4 | +---------------------------+------------+------------+ [ 301.281899] BUG: workqueue lockup - pool cpus=0 node=0 flags=0x0 nice=0 stuck for 46s! [ 301.281899] BUG: workqueue lockup - pool cpus=0 node=0 flags=0x0 nice=0 stuck for 46s! [ 301.303924] Showing busy workqueues and worker pools: [ 301.303924] Showing busy workqueues and worker pools: [ 301.318191] workqueue events: flags=0x0 [ 301.318191] workqueue events: flags=0x0 [ 301.329514] pwq 0: cpus=0 node=0 flags=0x0 nice=0 active=4/256 [ 301.329514] pwq 0: cpus=0 node=0 flags=0x0 nice=0 active=4/256 [ 301.338803] in-flight: 19:rht_deferred_worker [ 301.338803] in-flight: 19:rht_deferred_worker [ 301.338803] pending: tsc_refine_calibration_work, rht_deferred_worker, free_work [ 301.338803] pending: tsc_refine_calibration_work, rht_deferred_worker, free_work [ 301.386552] pool 0: cpus=0 node=0 flags=0x0 nice=0 hung=46s workers=2 idle: 3 [ 301.386552] pool 0: cpus=0 node=0 flags=0x0 nice=0 hung=46s workers=2 idle: 3 To reproduce: git clone git://git.kernel.org/pub/scm/linux/kernel/git/wfg/lkp-tests.git cd lkp-tests bin/lkp qemu -k <bzImage> job-script # job-script is attached in this email Thanks, Xiaolong