The following kernel warning is noticed on DUT arm64 Juno-r2 and x86 devices and Virtual environment qemu-arm64 and qemu-x86_64 running Linux next.

This is not a new regression and we have been noticing this warning on the Linux next kernel as per the available data.

List of devices encountering this kernel warning. - dragonboard-410c - juno-r2 - qemu-arm64 - qemu-riscv64 - qemu-x86_64 - x86_64

Anders bisected this down to, # first bad commit: [2e0199df252a536a03f4cb0810324dff523d1e79] sched/fair: Prepare exit/cleanup paths for delayed_dequeue

Reported-by: Linux Kernel Functional Testing lkft@linaro.org

Test log qemu-arm64 : ---------- [ 0.000000] Booting Linux on physical CPU 0x0000000000 [0x000f0510] [ 0.000000] Linux version 6.11.0-rc6-next-20240902 (tuxmake@tuxmake) (aarch64-linux-gnu-gcc (Debian 13.3.0-5) 13.3.0, GNU ld (GNU Binutils for Debian) 2.43) #1 SMP PREEMPT @1725295942 [ 0.000000] KASLR enabled [ 0.000000] random: crng init done [ 0.000000] Machine model: linux,dummy-virt .... cfs_bandwidth01.c:58: TINFO: Set 'worker1/cpu.max' = '3000 10000' cfs_bandwidth01.c:58: TINFO: Set 'worker2/cpu.max' = '2000 10000' cfs_bandwidth01.c:58: TINFO: Set 'worker3/cpu.max' = '3000 10000' cfs_bandwidth01.c:121: TPASS: Scheduled bandwidth constrained workers cfs_bandwidth01.c:58: TINFO: Set 'level2/cpu.max' = '5000 10000' cfs_bandwidth01.c:133: TPASS: Workers exited cfs_bandwidth01.c:121: TPASS: Scheduled bandwidth constrained workers <4>[ 76.364066] ------------[ cut here ]------------ <4>[ 76.364786] se->sched_delayed <4>[ 76.365535] WARNING: CPU: 0 PID: 0 at kernel/sched/fair.c:6058 unthrottle_cfs_rq (kernel/sched/fair.c:6058 (discriminator 1)) <4>[ 76.366982] Modules linked in: crct10dif_ce sm3_ce sm3 sha3_ce sha512_ce sha512_arm64 fuse drm backlight dm_mod ip_tables x_tables <4>[ 76.369703] CPU: 0 UID: 0 PID: 0 Comm: swapper/0 Not tainted 6.11.0-rc6-next-20240902 #1 <4>[ 76.370575] Hardware name: linux,dummy-virt (DT) <4>[ 76.371264] pstate: 624000c9 (nZCv daIF +PAN -UAO +TCO -DIT -SSBS BTYPE=--) <4>[ 76.371928] pc : unthrottle_cfs_rq (kernel/sched/fair.c:6058 (discriminator 1)) <4>[ 76.372353] lr : unthrottle_cfs_rq (kernel/sched/fair.c:6058 (discriminator 1)) <4>[ 76.372811] sp : ffff800080003d40 <4>[ 76.373158] x29: ffff800080003d40 x28: fff00000ff4c8fc0 x27: ffff942fdc51e4ae <4>[ 76.373978] x26: 0000000000000080 x25: 0000000000000000 x24: 0000000000000001 <4>[ 76.374670] x23: fff00000ff4c8fc0 x22: 0000000000000000 x21: fff0000005eec400 <4>[ 76.375312] x20: fff0000005f29800 x19: fff00000044d4c00 x18: 0000000000000006 <4>[ 76.375955] x17: fff06bd123665000 x16: ffff800080000000 x15: ffff8000800036d0 <4>[ 76.376600] x14: 0000000000000000 x13: 646579616c65645f x12: 64656863733e2d65 <4>[ 76.377284] x11: fffffffffffe0000 x10: ffff942fdbfe0238 x9 : ffff942fd9944c54 <4>[ 76.378034] x8 : 00000000ffffefff x7 : ffff942fdbfde390 x6 : 0000000000000147 <4>[ 76.378675] x5 : 0000000000000148 x4 : 40000000fffff147 x3 : 0000000000000000 <4>[ 76.379341] x2 : 0000000000000000 x1 : 0000000000000000 x0 : ffff942fdbf6ab00 <4>[ 76.380133] Call trace: <4>[ 76.380430] unthrottle_cfs_rq (kernel/sched/fair.c:6058 (discriminator 1)) <4>[ 76.380910] distribute_cfs_runtime (kernel/sched/fair.c:6254) <4>[ 76.381345] sched_cfs_period_timer (kernel/sched/fair.c:6307 kernel/sched/fair.c:6525) <4>[ 76.381765] __hrtimer_run_queues (kernel/time/hrtimer.c:1691 kernel/time/hrtimer.c:1755) <4>[ 76.382253] hrtimer_interrupt (kernel/time/hrtimer.c:1820) <4>[ 76.382629] arch_timer_handler_phys (drivers/clocksource/arm_arch_timer.c:675 drivers/clocksource/arm_arch_timer.c:692) <4>[ 76.383040] handle_percpu_devid_irq (kernel/irq/chip.c:942 (discriminator 2)) <4>[ 76.383442] generic_handle_domain_irq (kernel/irq/irqdesc.c:693 kernel/irq/irqdesc.c:748) <4>[ 76.383858] gic_handle_irq (drivers/irqchip/irq-gic.c:344 (discriminator 1)) <4>[ 76.384219] call_on_irq_stack (arch/arm64/kernel/entry.S:895) <4>[ 76.384591] do_interrupt_handler (arch/arm64/kernel/entry-common.c:310) <4>[ 76.385011] el1_interrupt (arch/arm64/kernel/entry-common.c:537 arch/arm64/kernel/entry-common.c:551) <4>[ 76.385377] el1h_64_irq_handler (arch/arm64/kernel/entry-common.c:557) <4>[ 76.385779] el1h_64_irq (arch/arm64/kernel/entry.S:594) <4>[ 76.386138] __schedule (kernel/sched/sched.h:1501 kernel/sched/core.c:6681) <4>[ 76.386481] schedule_idle (include/asm-generic/bitops/generic-non-atomic.h:128 include/linux/thread_info.h:192 include/linux/sched.h:2109 kernel/sched/core.c:6796) <4>[ 76.386822] do_idle (kernel/sched/idle.c:358) <4>[ 76.387149] cpu_startup_entry (kernel/sched/idle.c:423) <4>[ 76.387510] rest_init (main.c:?) <4>[ 76.387837] start_kernel (init/main.c:915 (discriminator 1)) <4>[ 76.388183] __primary_switched (arch/arm64/kernel/head.S:244) <4>[ 76.388714] ---[ end trace 0000000000000000 ]--- <4>[ 76.391991] ------------[ cut here ]------------ <4>[ 76.392496] delay && se->sched_delayed <4>[ 76.392585] WARNING: CPU: 1 PID: 0 at kernel/sched/fair.c:5486 dequeue_entity (kernel/sched/fair.c:5486 (discriminator 1)) <4>[ 76.393578] Modules linked in: crct10dif_ce sm3_ce sm3 sha3_ce sha512_ce sha512_arm64 fuse drm backlight dm_mod ip_tables x_tables <4>[ 76.400266] CPU: 1 UID: 0 PID: 0 Comm: swapper/1 Tainted: G W 6.11.0-rc6-next-20240902 #1 <4>[ 76.401509] Tainted: [W]=WARN <4>[ 76.402412] Hardware name: linux,dummy-virt (DT) <4>[ 76.403417] pstate: 624000c9 (nZCv daIF +PAN -UAO +TCO -DIT -SSBS BTYPE=--) <4>[ 76.404614] pc : dequeue_entity (kernel/sched/fair.c:5486 (discriminator 1)) <4>[ 76.405630] lr : dequeue_entity (kernel/sched/fair.c:5486 (discriminator 1)) <4>[ 76.406618] sp : ffff80008000bc00 <4>[ 76.407479] x29: ffff80008000bc00 x28: 0000000000000000 x27: 0000000000000009 <4>[ 76.408828] x26: fff0000005f29800 x25: fff0000004601300 x24: 0000000000000008 <4>[ 76.410693] x23: 0000000000000001 x22: 0000000000000000 x21: 0000000000000009 <4>[ 76.411616] x20: fff0000005f29800 x19: fff00000044d4c00 x18: 0000000000000006 <4>[ 76.413420] x17: fff06bd123687000 x16: ffff800080008000 x15: ffff80008000b590 <4>[ 76.414827] x14: 0000000000000000 x13: 646579616c65645f x12: 64656863733e2d65 <4>[ 76.415752] x11: fffffffffffe0000 x10: ffff942fdbfe0640 x9 : ffff942fd9944c54 <4>[ 76.417555] x8 : 00000000ffffefff x7 : ffff942fdbfde390 x6 : 0000000000000172 <4>[ 76.418529] x5 : 0000000000000173 x4 : 40000000fffff172 x3 : 0000000000000000 <4>[ 76.419887] x2 : 0000000000000000 x1 : 0000000000000000 x0 : fff0000003c83900 <4>[ 76.421775] Call trace: <4>[ 76.422157] dequeue_entity (kernel/sched/fair.c:5486 (discriminator 1)) <4>[ 76.423143] dequeue_entities (kernel/sched/fair.c:7099 (discriminator 1)) <4>[ 76.424546] dequeue_task_fair (kernel/sched/fair.c:7187 (discriminator 1)) <4>[ 76.425129] deactivate_task (kernel/sched/core.c:2075) <4>[ 76.426155] sched_balance_rq (kernel/sched/fair.c:9378 kernel/sched/fair.c:9513 kernel/sched/fair.c:11657) <4>[ 76.427142] sched_balance_domains (kernel/sched/fair.c:12078 (discriminator 1)) <4>[ 76.428151] sched_balance_softirq (kernel/sched/fair.c:12791) <4>[ 76.429218] handle_softirqs (arch/arm64/include/asm/jump_label.h:32 include/linux/jump_label.h:207 include/trace/events/irq.h:142 kernel/softirq.c:555) <4>[ 76.430268] __do_softirq (kernel/softirq.c:589) <4>[ 76.431615] ____do_softirq (arch/arm64/kernel/irq.c:82) <4>[ 76.432535] call_on_irq_stack (arch/arm64/kernel/entry.S:895) <4>[ 76.433171] do_softirq_own_stack (arch/arm64/kernel/irq.c:87) <4>[ 76.434232] irq_exit_rcu (kernel/softirq.c:435 kernel/softirq.c:637 kernel/softirq.c:649) <4>[ 76.435577] el1_interrupt (arch/arm64/include/asm/current.h:19 arch/arm64/kernel/entry-common.c:280 arch/arm64/kernel/entry-common.c:539 arch/arm64/kernel/entry-common.c:551) <4>[ 76.436496] el1h_64_irq_handler (arch/arm64/kernel/entry-common.c:557) <4>[ 76.437081] el1h_64_irq (arch/arm64/kernel/entry.S:594) <4>[ 76.438464] default_idle_call (kernel/sched/idle.c:126) <4>[ 76.439004] do_idle (kernel/sched/idle.c:186 kernel/sched/idle.c:326) <4>[ 76.439910] cpu_startup_entry (kernel/sched/idle.c:423) <4>[ 76.440930] secondary_start_kernel (arch/arm64/include/asm/atomic_ll_sc.h:95 (discriminator 2) arch/arm64/include/asm/atomic.h:28 (discriminator 2) include/linux/atomic/atomic-arch-fallback.h:546 (discriminator 2) include/linux/atomic/atomic-arch-fallback.h:994 (discriminator 2) include/linux/atomic/atomic-instrumented.h:436 (discriminator 2) include/linux/sched/mm.h:37 (discriminator 2) arch/arm64/kernel/smp.c:214 (discriminator 2)) <4>[ 76.442456] __secondary_switched (arch/arm64/kernel/head.S:418) <4>[ 76.443021] ---[ end trace 0000000000000000 ]--- cfs_bandwidth01.c:58: TINFO: Set 'level2/cpu.max' = '5000 10000' cfs_bandwidth01.c:133: TPASS: Workers exited cfs_bandwidth01.c:121: TPASS: Scheduled bandwidth constrained workers cfs_bandwidth01.c:58: TINFO: Set 'level2/cpu.max' = '5000 10000' cfs_bandwidth01.c:133: TPASS: Workers exited cfs_bandwidth01.c:121: TPASS: Scheduled bandwidth constrained workers cfs_bandwidth01.c:58: TINFO: Set 'level2/cpu.max' = '5000 10000' cfs_bandwidth01.c:133: TPASS: Workers exited cfs_bandwidth01.c:121: TPASS: Scheduled bandwidth constrained workers cfs_bandwidth01.c:58: TINFO: Set 'level2/cpu.max' = '5000 10000' cfs_bandwidth01.c:133: TPASS: Workers exited tst_test.c:1660: TFAIL: Kernel is now tainted.

HINT: You _MAY_ be missing kernel fixes:

https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?i... https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?i... https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?i... https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?i... https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?i... https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?i...

Summary: passed 10 failed 1

Links: ------ - https://qa-reports.linaro.org/lkft/linux-next-master/build/next-20240902/tes... - https://qa-reports.linaro.org/lkft/linux-next-master/build/next-20240902/tes...

Test history compare log: ------------ - https://qa-reports.linaro.org/lkft/linux-next-master/build/next-20240902/tes...

metadata: ---- git describe: next-20240902 git repo: https://gitlab.com/Linaro/lkft/mirrors/next/linux-next git sha: ecc768a84f0b8e631986f9ade3118fa37852fef0 kernel config: https://storage.tuxsuite.com/public/linaro/lkft/builds/2lWV3UVei3To0rSt5txVK... kernel version: 6.11.0-rc6 build url: https://storage.tuxsuite.com/public/linaro/lkft/builds/2lWV3UVei3To0rSt5txVK... toolchain: clang-18 and gcc-13 arch: arm64 and x86_64

Steps to reproduce: --------- - https://storage.tuxsuite.com/public/linaro/lkft/builds/2lWV3UVei3To0rSt5txVK... - https://storage.tuxsuite.com/public/linaro/lkft/builds/2lWV3UVei3To0rSt5txVK...

-- Linaro LKFT https://lkft.linaro.org