[BUG] lockdep splat using mmio tracer

Steven Rostedt
2022-12-02T02:32:05Z

I hit this while testing ftrace on an x86 32 bit VM (I've just started
converting my tests to run on a VM, which is find new found bugs).

[ 1111.130669] ================================
[ 1111.130670] WARNING: inconsistent lock state
[ 1111.130672] 6.1.0-rc6-test-00020-gbc591e45c100-dirty #245 Not tainted
[ 1111.130674] --------------------------------
[ 1111.130675] inconsistent {INITIAL USE} -> {IN-NMI} usage.
[ 1111.130676] kworker/0:0/3433 [HC1[1]:SC0[0]:HE0:SE1] takes:
[ 1111.130679] d3dc2b90 (kmmio_lock){....}-{2:2}, at: kmmio_die_notifier+0x70/0x140
[ 1111.130690] {INITIAL USE} state was registered at:
[ 1111.130691] lock_acquire+0xa2/0x2b0
[ 1111.130696] _raw_spin_lock_irqsave+0x36/0x60
[ 1111.130701] register_kmmio_probe+0x43/0x210
[ 1111.130704] mmiotrace_ioremap+0x188/0x1b0
[ 1111.130706] __ioremap_caller.constprop.0+0x257/0x340
[ 1111.130711] ioremap_wc+0x12/0x20
[ 1111.130713] ttm_bo_vmap+0x1d7/0x1f0 [ttm]
[ 1111.130722] qxl_bo_vmap_locked+0x75/0xa0 [qxl]
[ 1111.130728] qxl_draw_dirty_fb+0x2a2/0x440 [qxl]
[ 1111.130733] qxl_framebuffer_surface_dirty+0xfb/0x1d0 [qxl]
[ 1111.130737] drm_fb_helper_damage_work+0x181/0x350 [drm_kms_helper]
[ 1117.130757] process_one_work+0x21a/0x4e0
[ 1111.130759] worker_thread+0x14e/0x3a0
[ 1111.130761] kthread+0xea/0x110
[ 1111.130765] ret_from_fork+0x1c/0x28
[ 1111.130767] irq event stamp: 263958
[ 1111.130768] hardirqs last enabled at (263957): [<d3a0e292>] _raw_spin_unlock_irq+0x22/0x50
[ 1111.130773] hardirqs last disabled at (263958): [<d3a022bd>] exc_page_fault+0x2d/0x280
[ 1111.130777] softirqs last enabled at (263522): [<d3783201>] neigh_managed_work+0xa1/0xb0
[ 1111.130782] softirqs last disabled at (263518): [<d3783183>] neigh_managed_work+0x23/0xb0
[ 1111.130786]
[ 1111.130786] other info that might help us debug this:
[ 1111.130786] Possible unsafe locking scenario:
[ 1111.130786]
[ 1111.130787] CPU0
[ 1111.130787] ----
[ 1111.130788] lock(kmmio_lock);
[ 1111.130789] <Interrupt>
[ 1111.130790] lock(kmmio_lock);
[ 1111.130791]
[ 1111.130791] *** DEADLOCK ***
[ 1111.130791]
[ 1111.130791] 7 locks held by kworker/0:0/3433:
[ 1111.130797] #0: c100d4a8 ((wq_completion)events){+.+.}-{0:0}, at: process_one_work+0x1ac/0x4e0
[ 1111.130803] #1: c8391f44 ((work_completion)(&helper->damage_work)){+.+.}-{0:0}, at: process_one_work+0x1ac/0x4e0
[ 1111.130808] #2: c8391e94 (crtc_ww_class_acquire){+.+.}-{0:0}, at: qxl_framebuffer_surface_dirty+0x77/0x1d0 [qxl]
[ 1111.130815] #3: c18502b8 (crtc_ww_class_mutex){+.+.}-{3:3}, at: modeset_lock+0x67/0x200 [drm]
[ 1111.130863] #4: c7d1e8dc (reservation_ww_class_acquire){+.+.}-{0:0}, at: qxl_release_reserve_list+0x46/0x120 [qxl]
[ 1111.130871] #5: c1bd52f4 (reservation_ww_class_mutex){+.+.}-{3:3}, at: ttm_eu_reserve_buffers+0x2e5/0x4d0 [ttm]
[ 1111.130880] #6: d3e385ac (rcu_read_lock){....}-{1:2}, at: kmmio_handler+0x37/0x2e0
[ 1111.130886]
[ 1111.130886] stack backtrace:
[ 1111.130887] CPU: 0 PID: 3433 Comm: kworker/0:0 Not tainted 6.1.0-rc6-test-00020-gbc591e45c100-dirty #245
[ 1111.130890] Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.0-debian-1.16.0-4 04/01/2014
[ 1111.130892] Workqueue: events drm_fb_helper_damage_work [drm_kms_helper]
[ 1111.130909] Call Trace:
[ 1111.130911] dump_stack_lvl+0x4c/0x5f
[ 1111.130915] dump_stack+0xd/0x10
[ 1111.130918] print_usage_bug.part.0+0x16c/0x177
[ 1111.130924] lock_acquire.cold+0x31/0x37
[ 1111.130927] ? kmmio_die_notifier+0x70/0x140
[ 1111.130935] ? get_ins_imm_val+0xf0/0xf0
[ 1111.130938] _raw_spin_lock+0x2a/0x40
[ 1111.130942] ? kmmio_die_notifier+0x70/0x140
[ 1111.130945] kmmio_die_notifier+0x70/0x140
[ 1111.130948] ? arm_kmmio_fault_page+0xa0/0xa0
[ 1111.130951] atomic_notifier_call_chain+0x75/0x120
[ 1111.130955] notify_die+0x44/0x90
[ 1111.130959] exc_debug+0xd0/0x2a0
[ 1111.130965] ? exc_int3+0x100/0x100
[ 1111.130968] handle_exception+0x133/0x133
[ 1111.130970] EIP: qxl_draw_dirty_fb+0x2ae/0x440 [qxl]
[ 1111.130975] Code: 1c 85 db 75 a3 8b 45 d8 8d 55 e8 c7 45 e8 00 00 00 00 c7 45 ec 00 00 00 00 e8 4e d8 ff ff 85 c0 75 86 8b 75 e8 8b 5d 14 89 1e <8b> 5d cc c7 46 10 00 00 00 00 c7 46 14 00 00 00 00 c7 46 08 00 00
[ 1111.130978] EAX: 00000000 EBX: 00000001 ECX: d3090bc0 EDX: 00000001
[ 1111.130980] ESI: f7cd3000 EDI: 00000138 EBP: c8391e44 ESP: c8391dec
[ 1111.130981] DS: 007b ES: 007b FS: 00d8 GS: 0000 SS: 0068 EFLAGS: 00000146
[ 1111.130984] ? iomem_map_sanity_check+0xf0/0x100
[ 1111.130990] ? sysvec_kvm_posted_intr_nested_ipi+0xb/0xa0
[ 1111.130994] ? exc_int3+0x100/0x100
[ 1111.130998] ? exc_int3+0x100/0x100
[ 1111.131002] ? qxl_draw_dirty_fb+0x2ae/0x440 [qxl]
[ 1111.131011] qxl_framebuffer_surface_dirty+0xfb/0x1d0 [qxl]
[ 1111.131022] ? qxl_create_plane+0xd0/0xd0 [qxl]
[ 1111.131026] drm_fb_helper_damage_work+0x181/0x350 [drm_kms_helper]
[ 1111.131046] process_one_work+0x21a/0x4e0
[ 1111.131052] worker_thread+0x14e/0x3a0
[ 1111.131056] kthread+0xea/0x110
[ 1111.131059] ? process_one_work+0x4e0/0x4e0
[ 1111.131062] ? kthread_complete_and_exit+0x20/0x20
[ 1111.131066] ret_from_fork+0x1c/0x28

I never hit this before, but then again, mmio tracer is showing output on
the VM which it did not do on the baremetal machine.

-- Steve