On Thu, Mar 12, 2026 at 11:10:24PM -0700, Ron Economos wrote:
I'm seeing this WARN on RISC-V in the same place.
Starting systemd-udevd version 255.4-1ubuntu8.12 [ 5.417957] usb 1-2: new high-speed USB device number 2 using xhci_hcd [ 5.765956] ------------[ cut here ]------------ [ 5.765976] WARNING: CPU: 0 PID: 17 at kernel/sched/fair.c:5266 place_entity+0x130/0x138 [ 5.766013] Modules linked in: [ 5.766028] CPU: 0 UID: 0 PID: 17 Comm: rcu_preempt Not tainted 6.12.77-rc1 #2 [ 5.766038] Hardware name: SiFive HiFive Unmatched A00 (DT) [ 5.766043] epc : place_entity+0x130/0x138 [ 5.766052] ra : place_entity+0x9c/0x138 [ 5.766061] epc : ffffffff800721c8 ra : ffffffff80072134 sp : ffffffc6000a3af0 [ 5.766067] gp : ffffffff823a8a70 tp : ffffffd6808c1d80 t0 : 0000000000000000 [ 5.766072] t1 : 0000000000000000 t2 : 0000000000000000 s0 : ffffffc6000a3b30 [ 5.766078] s1 : ffffffd9fed138c0 a0 : 0000000000577fff a1 : ffffffd681175400 [ 5.766084] a2 : 0000000000000000 a3 : 0000000000000177 a4 : 0000000000000000 [ 5.766089] a5 : 0000000026fdb4a5 a6 : 0000000000000000 a7 : 0000000000000002 [ 5.766095] s2 : 0000000000000000 s3 : ffffffd9fed137c0 s4 : ffffffd682b1d880 [ 5.766100] s5 : 0000000000000200 s6 : 0000000000000003 s7 : 0000000000000001 [ 5.766106] s8 : ffffffd9fed138c0 s9 : 0000000000200b20 s10: ffffffd681175400 [ 5.766112] s11: 0000000000000000 t3 : 0000000000000000 t4 : 0000000000000000 [ 5.766117] t5 : 0000000000000000 t6 : 0000000000000000 [ 5.766121] status: 0000000200000100 badaddr: 0000000000000177 cause: 0000000000000003 [ 5.766130] [<ffffffff800721c8>] place_entity+0x130/0x138 [ 5.766141] [<ffffffff80072780>] reweight_entity+0x178/0x1a0 [ 5.766151] [<ffffffff8007285e>] update_cfs_group+0x76/0xa8 [ 5.766161] [<ffffffff80073340>] dequeue_entities+0x120/0x550 [ 5.766171] [<ffffffff800738c4>] pick_task_fair+0x84/0x108 [ 5.766179] [<ffffffff8007b954>] pick_next_task_fair+0x1c/0x1b0 [ 5.766192] [<ffffffff80e2fe72>] __schedule+0x172/0xc10 [ 5.766204] [<ffffffff80e30932>] schedule+0x22/0x140 [ 5.766212] [<ffffffff80e36df0>] schedule_timeout+0x80/0x180 [ 5.766226] [<ffffffff800d3586>] rcu_gp_fqs_loop+0xfe/0x4d0 [ 5.766243] [<ffffffff800d6a12>] rcu_gp_kthread+0x122/0x158 [ 5.766255] [<ffffffff80050280>] kthread+0xc8/0xe8 [ 5.766268] [<ffffffff80e39cce>] ret_from_fork+0xe/0x18 [ 5.766282] ---[ end trace 0000000000000000 ]--- [ 5.992429] usb 1-2: New USB device found, idVendor=174c, idProduct=2074, bcdDevice= 0.01 [ 5.999916] usb 1-2: New USB device strings: Mfr=2, Product=3, SerialNumber=1 [ 6.007028] usb 1-2: Product: AS2107
Similar warning on i.MX8MP
[ 6.426039] ------------[ cut here ]------------ [ 6.426058] WARNING: CPU: 0 PID: 1 at /kernel/sched/fair.c:5266 place_entity+0x114/0x120 [ 6.426082] Modules linked in: rfcomm uas ahci libahci libata nls_iso8859_1 bnep onboard_usb_dev nls_cp437 dwc3 snd_soc_hdmi_codec dw_hdmi_cec dw_hdmi_gp_audio imx8mp_interconnect spidev caam_jr caamhash_desc caamalg_desc crypto_engine rng_core authenc libdes crypto_null evdev aes_ce_blk aes_ce_cipher ghash_ce gf128mul imx8mp_hdmi_tx snd_soc_imx_hdmi sha2_ce sha256_arm64 sha1_ce hantro_vpu sha1_generic snd_soc_simple_card fsl_imx8_ddr_perf dw_hdmi snd_soc_simple_card_utils cec v4l2_vp9 mwifiex_sdio v4l2_h264 drm_display_helper hci_uart phy_fsl_imx8mq_usb mwifiex phy_fsl_samsung_hdmi phy_fsl_imx8m_pcie imx8mp_hdmi_pvi snd_soc_fsl_sai snd_soc_fsl_utils bluetooth etnaviv governor_userspace imx_pcm_dma ecdh_generic gpu_sched dwc3_imx8mp cfg80211 samsung_dsim snd_soc_fsl_aud2htx imx_bus ecc rfkill ti_ads1015 libaes industrialio_triggered_buffer kfifo_buf snd_soc_wm8904 ina2xx lm75 lontium_lt8912b imx_sdma spi_nxp_fspi caam error snvs_pwrkey nvmem_snvs_lpgpr flexcan usb_conn_gpio can_dev imx8mm_thermal spi_imx pwm_imx27 [ 6.426327] roles display_connector gpio_keys fuse ipv6 autofs4 [ 6.426353] CPU: 0 UID: 0 PID: 1 Comm: systemd Not tainted 6.12.77-rc1-7.6.0-devel #1 [ 6.426363] Hardware name: Toradex Verdin iMX8M Plus WB on Dahlia Board (DT) [ 6.426368] pstate: 200000c5 (nzCv daIF -PAN -UAO -TCO -DIT -SSBS BTYPE=--) [ 6.426376] pc : place_entity+0x114/0x120 [ 6.426387] lr : place_entity+0xf4/0x120 [ 6.426395] sp : ffff80008003b9c0 [ 6.426399] x29: ffff80008003b9c0 x28: 0000000000000001 x27: 0000000000000000 [ 6.426412] x26: ffff67c13fb80180 x25: ffff67c0ce69e600 x24: 0000000000000001 [ 6.426424] x23: 0000000000000000 x22: 0000000000000000 x21: 00000000000003ce [ 6.426436] x20: ffff67c13fb80180 x19: ffff67c0ce69e600 x18: 0000000000000001 [ 6.426448] x17: 0000000000000000 x16: 0000000000000000 x15: 036d98d79167f52c [ 6.426460] x14: 000000000000000c x13: 0000000000000001 x12: 0000000000200b20 [ 6.426472] x11: 0000000000200b20 x10: fffffffffff0251c x9 : 0000000000000000 [ 6.426484] x8 : 00000000000003ce x7 : ffff67c13fb80180 x6 : ffff67c0ce69e600 [ 6.426496] x5 : 00000000672c7516 x4 : 00000000ffffffe0 x3 : 0000000000000000 [ 6.426508] x2 : 00000000000003ce x1 : 0000000000000000 x0 : 000000000021b03a [ 6.426520] Call trace: [ 6.426525] place_entity+0x114/0x120 [ 6.426533] reweight_entity+0x1d0/0x1f8 [ 6.426542] update_cfs_group+0x8c/0xac [ 6.426550] enqueue_task_fair+0x27c/0x5d0 [ 6.426559] sched_move_task+0x130/0x1ec [ 6.426567] cpu_cgroup_attach+0x40/0x80 [ 6.426574] cgroup_migrate_execute+0x368/0x428 [ 6.426584] cgroup_update_dfl_csses+0x230/0x26c [ 6.426594] cgroup_subtree_control_write+0x3f4/0x454 [ 6.426603] cgroup_file_write+0xa4/0x1b0 [ 6.426610] kernfs_fop_write_iter+0x130/0x1dc [ 6.426621] vfs_write+0x208/0x374 [ 6.426629] ksys_write+0x74/0x10c [ 6.426636] __arm64_sys_write+0x1c/0x28 [ 6.426643] invoke_syscall.constprop.0+0x50/0xe4 [ 6.426653] do_el0_svc+0x40/0xc4 [ 6.426661] el0_svc+0x38/0x158 [ 6.426669] el0t_64_sync_handler+0x120/0x12c [ 6.426676] el0t_64_sync+0x190/0x194 [ 6.426684] ---[ end trace 0000000000000000 ]---