On Fri, Jun 19, 2020 at 12:03 PM Dmitry Vyukov <dvyukov@xxxxxxxxxx> wrote: > > On Fri, Jun 19, 2020 at 11:53 AM Peter Zijlstra <peterz@xxxxxxxxxxxxx> wrote: > > > > On Thu, Jun 18, 2020 at 02:17:15PM -0700, syzbot wrote: > > > > > INFO: trying to register non-static key. > > > the code is fine but needs lockdep annotation. > > > turning off the locking correctness validator. > > > CPU: 0 PID: 0 Comm: swapper/0 Not tainted 5.7.0-syzkaller #0 > > > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 > > > Call Trace: > > > <IRQ> > > > __dump_stack lib/dump_stack.c:77 [inline] > > > dump_stack+0xf6/0x16e lib/dump_stack.c:118 > > > assign_lock_key kernel/locking/lockdep.c:894 [inline] > > > register_lock_class+0x1442/0x17e0 kernel/locking/lockdep.c:1206 > > > arch_stack_walk+0x81/0xf0 arch/x86/kernel/stacktrace.c:25 > > > lock_downgrade+0x720/0x720 kernel/locking/lockdep.c:4624 > > > is_dynamic_key+0x1b0/0x1b0 kernel/locking/lockdep.c:1176 > > > trace_hardirqs_off+0x50/0x1f0 kernel/trace/trace_preemptirq.c:83 > > > __lock_acquire+0x101/0x6270 kernel/locking/lockdep.c:4259 > > > save_stack+0x32/0x40 mm/kasan/common.c:50 > > > > So I'm thinking this is in fact: > > > > spin_lock_irqsave(&depot_lock, flags); > > > > from lib/stackdepot.c:stack_depot_save(), which has gone missing from > > the stack due to tail-call optimizations. > > > > Now depot_lock is declared thusly: > > > > static DEFINE_SPINLOCK(depot_lock); > > > > and I'm trying to figure out how lockdep manages to conclude that isn't > > static storage.... most odd. > > Note there also was something wrong with the unwinder: > https://syzkaller.appspot.com/x/log.txt?x=13f305a9100000 > (or with something else in the kernel), so potentially it did not > happen save_stack. > > In fact, Andrey just reverted this parsing of questionable frames in syzkaller: > https://github.com/google/syzkaller/commit/4d2d1ebee3b65c404576d1c8573a0ec48b03b883 > (was done because of what turned out to be ORC unwinder bug, which was fixed). > > So potentially we just need to close this is invalid now. Rerunning the repro shows a different stack: INFO: trying to register non-static key. the code is fine but needs lockdep annotation. turning off the locking correctness validator. CPU: 0 PID: 0 Comm: swapper/0 Not tainted 5.8.0-rc1+ #2 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.13.0-1 04/01/2014 Call Trace: <IRQ> __dump_stack lib/dump_stack.c:77 dump_stack+0xf6/0x16e lib/dump_stack.c:118 assign_lock_key kernel/locking/lockdep.c:894 register_lock_class+0x1228/0x16d0 kernel/locking/lockdep.c:1206 __lock_acquire+0x100/0x6950 kernel/locking/lockdep.c:4259 lock_acquire+0x18b/0x7c0 kernel/locking/lockdep.c:4959 __raw_spin_lock_irqsave ./include/linux/spinlock_api_smp.h:110 _raw_spin_lock_irqsave+0x32/0x50 kernel/locking/spinlock.c:159 ath9k_htc_rxep+0x31/0x210 drivers/net/wireless/ath/ath9k/htc_drv_txrx.c:1128 ath9k_htc_rx_msg+0x2d9/0xb10 drivers/net/wireless/ath/ath9k/htc_hst.c:459 ath9k_hif_usb_rx_stream drivers/net/wireless/ath/ath9k/hif_usb.c:638 ath9k_hif_usb_rx_cb+0xc76/0x1050 drivers/net/wireless/ath/ath9k/hif_usb.c:671 __usb_hcd_giveback_urb+0x29a/0x550 drivers/usb/core/hcd.c:1650 usb_hcd_giveback_urb+0x367/0x410 drivers/usb/core/hcd.c:1716 dummy_timer+0x125d/0x333b drivers/usb/gadget/udc/dummy_hcd.c:1967 call_timer_fn+0x1ac/0x6e0 kernel/time/timer.c:1404 expire_timers kernel/time/timer.c:1449 __run_timers kernel/time/timer.c:1773 __run_timers kernel/time/timer.c:1740 run_timer_softirq+0x5e5/0x14c0 kernel/time/timer.c:1786 __do_softirq+0x21e/0x98b kernel/softirq.c:292 asm_call_on_stack+0xf/0x20 arch/x86/entry/entry_64.S:711 </IRQ> __run_on_irqstack ./arch/x86/include/asm/irq_stack.h:22 run_on_irqstack_cond ./arch/x86/include/asm/irq_stack.h:48 do_softirq_own_stack+0x109/0x140 arch/x86/kernel/irq_64.c:77 invoke_softirq kernel/softirq.c:387 __irq_exit_rcu kernel/softirq.c:417 irq_exit_rcu+0x16f/0x1a0 kernel/softirq.c:429 sysvec_apic_timer_interrupt+0xd3/0x1b0 arch/x86/kernel/apic/apic.c:1091 asm_sysvec_apic_timer_interrupt+0x12/0x20 ./arch/x86/include/asm/idtentry.h:596 RIP: 0010:native_safe_halt ./arch/x86/include/asm/irqflags.h:60 RIP: 0010:arch_safe_halt ./arch/x86/include/asm/irqflags.h:103 RIP: 0010:default_idle+0x28/0x2f0 arch/x86/kernel/process.c:700 Code: cc cc 41 56 41 55 65 44 8b 2d 44 77 66 7a 41 54 55 53 0f 1f 44 00 00 e8 f6 d7 a9 fb e9 07 00 00 00 0f 00 2d 2a 34 47 00 fb f4 <65> 44 8b 2d 20 77 66 7a 0f 1f 44 00 00 5b 5d 41 3 RSP: 0018:ffffffff87007da0 EFLAGS: 00000246 RAX: 0000000000000000 RBX: ffffffff8702f840 RCX: 1ffffffff0fd45ea RDX: 1ffffffff0e0600f RSI: 0000000000000000 RDI: ffffffff87030078 RBP: fffffbfff0e05f08 R08: 0000000000000000 R09: 0000000000000001 R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000 R13: 0000000000000000 R14: ffffffff87ea1fc8 R15: 0000000000000000 cpuidle_idle_call kernel/sched/idle.c:154 do_idle+0x3ec/0x510 kernel/sched/idle.c:269 cpu_startup_entry+0x14/0x20 kernel/sched/idle.c:365 start_kernel+0x9fc/0xa39 init/main.c:1043 secondary_startup_64+0xb6/0xc0 arch/x86/kernel/head_64.S:243 So this is a dup of: #syz dup: INFO: trying to register non-static key in ath9k_htc_rxep Not sure why lockdep triggered on save_stack() in this run.
