Hi, while doing final testing before sending a pull request, I merged in linux-next, and commit 5b9ce7ecd7: virtio_balloon: stay awake while adjusting balloon seems to be causing a lockdep warning (see attached) when running gce-xfstests on a Google Compute Engine e2 VM. I was not able to trigger it using kvm-xfstests, but the following command: "gce-xfstests -C 10 ext4/4k generic/476) was sufficient to triger the problem. For more information please see [1] and [2]. [1] https://github.com/tytso/xfstests-bld/blob/master/Documentation/gce-xfstests.md [2] https://thunk.org/gce-xfstests I found it by looking at the git logs, and this commit aroused my suspicions, and I further testing showed that the lockdep warning was reproducible with this commit, but not when testing with the immediately preceeding commit (15b9ce7ecd^). Cheers, - Ted root: ext4/4k run xfstest generic/476 systemd[1]: Started fstests-generic-476.scope - /usr/bin/bash -c test -w /proc/self/oom_score_adj && echo 250 > /proc/self/oom_score_adj; exec ./tests/generic/476. kernel: [ 399.361181] EXT4-fs (dm-1): mounted filesystem 840e25bd-f650-4819-8562-7eded85ef370 r/w with ordered data mode. Quota mode: none. systemd[1]: fstests-generic-476.scope: Deactivated successfully. systemd[1]: fstests-generic-476.scope: Consumed 3min 1.966s CPU time. systemd[1]: xt\x2dvdb.mount: Deactivated successfully. kernel: [ 537.085404] EXT4-fs (dm-0): unmounting filesystem d3d7a675-f7b6-4384-abec-2e60d885b6da. systemd[1]: xt\x2dvdc.mount: Deactivated successfully. kernel: [ 540.565870] kernel: [ 540.567523] ================================ kernel: [ 540.572007] WARNING: inconsistent lock state kernel: [ 540.576407] 6.7.0-rc3-xfstests-lockdep-00012-g5b9ce7ecd715 #318 Not tainted kernel: [ 540.583532] -------------------------------- kernel: [ 540.587928] inconsistent {IN-HARDIRQ-W} -> {HARDIRQ-ON-W} usage. kernel: [ 540.594326] kworker/0:3/329 [HC0[0]:SC0[0]:HE1:SE1] takes: kernel: [ 540.599955] ffff90b280a548c0 (&vb->adjustment_lock){?...}-{2:2}, at: update_balloon_size_func+0x33/0x190 kernel: [ 540.609926] {IN-HARDIRQ-W} state was registered at: kernel: [ 540.614935] __lock_acquire+0x3f2/0xb30 kernel: [ 540.618992] lock_acquire+0xbf/0x2b0 kernel: [ 540.622786] _raw_spin_lock_irqsave+0x43/0x90 kernel: [ 540.627366] virtballoon_changed+0x51/0xd0 kernel: [ 540.631947] virtio_config_changed+0x5a/0x70 kernel: [ 540.636437] vp_config_changed+0x11/0x20 kernel: [ 540.640576] __handle_irq_event_percpu+0x88/0x230 kernel: [ 540.645500] handle_irq_event+0x38/0x80 kernel: [ 540.649558] handle_edge_irq+0x8f/0x1f0 kernel: [ 540.653791] __common_interrupt+0x47/0xf0 kernel: [ 540.658106] common_interrupt+0x79/0xa0 kernel: [ 540.661672] EXT4-fs (dm-1): unmounting filesystem 840e25bd-f650-4819-8562-7eded85ef370. kernel: [ 540.663183] asm_common_interrupt+0x26/0x40 kernel: [ 540.663190] acpi_safe_halt+0x1b/0x30 kernel: [ 540.663196] acpi_idle_enter+0x7b/0xd0 kernel: [ 540.663199] cpuidle_enter_state+0x90/0x4f0 kernel: [ 540.688723] cpuidle_enter+0x2d/0x40 kernel: [ 540.692516] cpuidle_idle_call+0xe4/0x120 kernel: [ 540.697036] do_idle+0x84/0xd0 kernel: [ 540.700393] cpu_startup_entry+0x2a/0x30 kernel: [ 540.704588] rest_init+0xe9/0x180 kernel: [ 540.708118] arch_call_rest_init+0xe/0x30 kernel: [ 540.712426] start_kernel+0x41c/0x4b0 kernel: [ 540.716310] x86_64_start_reservations+0x18/0x30 kernel: [ 540.721164] x86_64_start_kernel+0x8c/0x90 kernel: [ 540.725737] secondary_startup_64_no_verify+0x178/0x17b kernel: [ 540.731432] irq event stamp: 22681 kernel: [ 540.734956] hardirqs last enabled at (22681): [<ffffffff8b4b5158>] _raw_spin_unlock_irq+0x28/0x50 kernel: [ 540.744564] hardirqs last disabled at (22680): [<ffffffff8b4b4ded>] _raw_spin_lock_irq+0x5d/0x90 kernel: [ 540.753475] softirqs last enabled at (22076): [<ffffffff8a58cfa1>] srcu_invoke_callbacks+0x101/0x1c0 kernel: [ 540.762904] softirqs last disabled at (22072): [<ffffffff8a58cfa1>] srcu_invoke_callbacks+0x101/0x1c0 kernel: [ 540.773298] kernel: [ 540.773298] other info that might help us debug this: kernel: [ 540.780207] Possible unsafe locking scenario: kernel: [ 540.780207] kernel: [ 540.786438] CPU0 kernel: [ 540.789007] ---- kernel: [ 540.791766] lock(&vb->adjustment_lock); kernel: [ 540.796014] <Interrupt> kernel: [ 540.798778] lock(&vb->adjustment_lock); kernel: [ 540.803605] kernel: [ 540.803605] *** DEADLOCK *** kernel: [ 540.803605] kernel: [ 540.809840] 2 locks held by kworker/0:3/329: kernel: [ 540.814259] #0: ffff90b280079148 ((wq_completion)events_freezable){+.+.}-{0:0}, at: process_one_work+0x1a6/0x500 kernel: [ 540.824952] #1: ffff9e3b40d1fe50 ((work_completion)(&vb->update_balloon_size_work)){+.+.}-{0:0}, at: process_one_work+0x1a6/0x500 kernel: [ 540.837088] kernel: [ 540.837088] stack backtrace: kernel: [ 540.841584] CPU: 0 PID: 329 Comm: kworker/0:3 Not tainted 6.7.0-rc3-xfstests-lockdep-00012-g5b9ce7ecd715 #318 kernel: [ 540.851632] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 11/17/2023 kernel: [ 540.861148] Workqueue: events_freezable update_balloon_size_func kernel: [ 540.867306] Call Trace: kernel: [ 540.869914] <TASK> kernel: [ 540.872136] dump_stack_lvl+0x4a/0x80 kernel: [ 540.876012] mark_lock_irq+0x3a5/0x5a0 kernel: [ 540.879973] ? stack_trace_save+0x55/0x80 kernel: [ 540.884105] ? save_trace+0x66/0x200 kernel: [ 540.887894] mark_lock+0x1f3/0x3f0 kernel: [ 540.891417] mark_usage+0xe1/0x140 kernel: [ 540.895060] __lock_acquire+0x3f2/0xb30 kernel: [ 540.899020] lock_acquire+0xbf/0x2b0 kernel: [ 540.902722] ? update_balloon_size_func+0x33/0x190 kernel: [ 540.908073] ? lock_acquire+0xbf/0x2b0 kernel: [ 540.912059] ? process_one_work+0x1a6/0x500 kernel: [ 540.916388] ? process_one_work+0x1a6/0x500 kernel: [ 540.920808] _raw_spin_lock+0x34/0x80 kernel: [ 540.924646] ? update_balloon_size_func+0x33/0x190 kernel: [ 540.929677] update_balloon_size_func+0x33/0x190 kernel: [ 540.934510] ? process_one_work+0x1a6/0x500 kernel: [ 540.939000] process_one_work+0x20f/0x500 kernel: [ 540.943383] worker_thread+0x1e1/0x3d0 kernel: [ 540.947391] ? __pfx_worker_thread+0x10/0x10 kernel: [ 540.952103] kthread+0xf5/0x130 kernel: [ 540.955392] ? __pfx_kthread+0x10/0x10 kernel: [ 540.959290] ret_from_fork+0x31/0x50 kernel: [ 540.963193] ? __pfx_kthread+0x10/0x10 kernel: [ 540.967157] ret_from_fork_asm+0x1b/0x30 kernel: [ 540.971205] </TASK> kernel: [ 550.008710] EXT4-fs (dm-1): mounted filesystem 840e25bd-f650-4819-8562-7eded85ef370 r/w with ordered data mode. Quota mode: none. systemd[1]: xt\x2dvdc.mount: Deactivated successfully. kernel: [ 550.033770] EXT4-fs (dm-1): unmounting filesystem 840e25bd-f650-4819-8562-7eded85ef370. root: gce-xfstests: checking for hook post-xfstests root: gce-xfstests: checking for hook pre-xfstests
