On 07/07/21 09:35, Guenter Roeck wrote: > I think I have it. pseries_defconfig, and pseries emulation, > started with "-smp 2" and qemu-system-ppc64: > > [ 0.731644][ T1] smp: Bringing up secondary CPUs ...^M > [ 0.750546][ T0] BUG: scheduling while atomic: swapper/1/0/0x00000000^M > [ 0.752119][ T0] no locks held by swapper/1/0.^M > [ 0.752309][ T0] Modules linked in:^M > [ 0.752684][ T0] CPU: 1 PID: 0 Comm: swapper/1 Not tainted 5.13.0-11855-g77d34a4683b0 #1^M > [ 0.753197][ T0] Call Trace:^M > [ 0.753334][ T0] [c000000008737b20] [c0000000009f9b18] .dump_stack_lvl+0xa4/0x100 (unreliable)^M > [ 0.754224][ T0] [c000000008737bb0] [c000000000190ed0] .__schedule_bug+0xa0/0xe0^M > [ 0.754459][ T0] [c000000008737c30] [c000000001182518] .__schedule+0xc08/0xd90^M > [ 0.754738][ T0] [c000000008737d20] [c000000001182b8c] .schedule_idle+0x2c/0x60^M > [ 0.754945][ T0] [c000000008737d90] [c0000000001a48ec] .do_idle+0x29c/0x3c0^M > [ 0.755145][ T0] [c000000008737e60] [c0000000001a4df0] .cpu_startup_entry+0x30/0x40^M > [ 0.755403][ T0] [c000000008737ee0] [c00000000005ef10] .start_secondary+0x2c0/0x300^M > [ 0.755621][ T0] [c000000008737f90] [c00000000000d254] start_secondary_prolog+0x10/0x14^M > [ 0.764164][ T1] smp: Brought up 1 node, 2 CPUs^M > > Guenter Hmph, I was about to say I couldn't get that, but after cycling between different PREEMPT options I finally triggered it, so thanks for that! Same sha1 as yours, invocation is: qemu-system-ppc64 vmlinux -smp 2 -nographic -m 1024 -machine pseries,usb=off with pseries_defconfig + CONFIG_DEBUG_ATOMIC_SLEEP + CONFIG_PREEMPT_VOLUNTARY Now to dig!