[+ some other folks] On Fri, Dec 13, 2024 at 04:30:24AM -0800, syzbot wrote: > syzbot has found a reproducer for the following issue on: > > HEAD commit: 2e7aff49b5da Merge branches 'for-next/core' and 'for-next/.. > git tree: git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci > console output: https://syzkaller.appspot.com/x/log.txt?x=11ed5be8580000 > kernel config: https://syzkaller.appspot.com/x/.config?x=696fb014d05da3a3 > dashboard link: https://syzkaller.appspot.com/bug?extid=e13e654d315d4da1277c > compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40 > userspace arch: arm64 > syz repro: https://syzkaller.appspot.com/x/repro.syz?x=10192d44580000 > > Downloadable assets: > disk image: https://storage.googleapis.com/syzbot-assets/ef408f67fde3/disk-2e7aff49.raw.xz > vmlinux: https://storage.googleapis.com/syzbot-assets/414ac17a20dc/vmlinux-2e7aff49.xz > kernel image: https://storage.googleapis.com/syzbot-assets/a93415d2a7e7/Image-2e7aff49.gz.xz > > IMPORTANT: if you fix the issue, please add the following tag to the commit: > Reported-by: syzbot+e13e654d315d4da1277c@xxxxxxxxxxxxxxxxxxxxxxxxx I spent a bit of time looking at the reports in the "dashboard link" above. There are quite a few in there and I ended up suspecting the bluetooth subsystem and drivers using hci_register_dev(). Specifically, it looks like one of the workqueues is serviced in softirq context after its corresponding device has been destroyed. I wasn't able to reproduce it locally (I don't have a setup for running the 'syz' reproducers), but the program is pretty small (see the "syz repro" link above). Given that this seems to explode a few times a month, I wonder if it's worth adding some instrumentation to e.g. dump the name of the workqueue? Will --->8 (mammoth backtrace below) > ------------[ cut here ]------------ > WARNING: CPU: 1 PID: 6023 at kernel/workqueue.c:2257 current_wq_worker kernel/workqueue_internal.h:69 [inline] > WARNING: CPU: 1 PID: 6023 at kernel/workqueue.c:2257 is_chained_work kernel/workqueue.c:2199 [inline] > WARNING: CPU: 1 PID: 6023 at kernel/workqueue.c:2257 __queue_work+0xe50/0x1308 kernel/workqueue.c:2256 > Modules linked in: > CPU: 1 UID: 0 PID: 6023 Comm: klogd Not tainted 6.13.0-rc2-syzkaller-g2e7aff49b5da #0 > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/13/2024 > pstate: 404000c5 (nZcv daIF +PAN -UAO -TCO -DIT -SSBS BTYPE=--) > pc : __queue_work+0xe50/0x1308 kernel/workqueue_internal.h:69 > lr : current_wq_worker kernel/workqueue_internal.h:69 [inline] > lr : is_chained_work kernel/workqueue.c:2199 [inline] > lr : __queue_work+0xe50/0x1308 kernel/workqueue.c:2256 > sp : ffff800080017b40 > x29: ffff800080017b90 x28: dfff800000000000 x27: ffff700010002f88 > x26: dfff800000000000 x25: ffff0000d1c63800 x24: 0000000000000008 > x23: 1fffe0001b14d791 x22: ffff0000d1c639c0 x21: 0000000000000100 > x20: ffff0000d8a6bc80 x19: ffff0000da2f0930 x18: 1fffe000366c5e7e > x17: ffff800123d64000 x16: ffff80008326d65c x15: 0000000000000002 > x14: 1ffff00011f300ca x13: dfff800000000000 x12: 00000000b1aebe1c > x11: 00000000beaa9035 x10: 0000000000ff0100 x9 : 0000000000000000 > x8 : ffff0000d8a6bc80 x7 : ffff8000805819c0 x6 : 0000000000000000 > x5 : 0000000000000001 x4 : 0000000000000001 x3 : ffff80008df6a320 > x2 : ffff0000da2f0930 x1 : 0000000000000100 x0 : 0000000000000000 > Call trace: > current_wq_worker kernel/workqueue_internal.h:69 [inline] (P) > is_chained_work kernel/workqueue.c:2199 [inline] (P) > __queue_work+0xe50/0x1308 kernel/workqueue.c:2256 (P) > current_wq_worker kernel/workqueue_internal.h:69 [inline] (L) > is_chained_work kernel/workqueue.c:2199 [inline] (L) > __queue_work+0xe50/0x1308 kernel/workqueue.c:2256 (L) > delayed_work_timer_fn+0x74/0x90 kernel/workqueue.c:2485 > call_timer_fn+0x1b4/0x8b8 kernel/time/timer.c:1793 > expire_timers kernel/time/timer.c:1839 [inline] > __run_timers kernel/time/timer.c:2418 [inline] > __run_timer_base+0x59c/0x7b4 kernel/time/timer.c:2430 > run_timer_base kernel/time/timer.c:2439 [inline] > run_timer_softirq+0xcc/0x194 kernel/time/timer.c:2449 > handle_softirqs+0x320/0xd34 kernel/softirq.c:554 > __do_softirq+0x14/0x20 kernel/softirq.c:588 > ____do_softirq+0x14/0x20 arch/arm64/kernel/irq.c:81 > call_on_irq_stack+0x24/0x4c arch/arm64/kernel/entry.S:891 > do_softirq_own_stack+0x20/0x2c arch/arm64/kernel/irq.c:86 > invoke_softirq kernel/softirq.c:435 [inline] > __irq_exit_rcu+0x1d8/0x544 kernel/softirq.c:655 > irq_exit_rcu+0x14/0x84 kernel/softirq.c:671 > __el1_irq arch/arm64/kernel/entry-common.c:561 [inline] > el1_interrupt+0x38/0x68 arch/arm64/kernel/entry-common.c:575 > el1h_64_irq_handler+0x18/0x24 arch/arm64/kernel/entry-common.c:580 > el1h_64_irq+0x6c/0x70 arch/arm64/kernel/entry.S:596 > __daif_local_irq_enable arch/arm64/include/asm/irqflags.h:26 [inline] (P) > arch_local_irq_enable arch/arm64/include/asm/irqflags.h:48 [inline] (P) > raw_spin_rq_unlock_irq kernel/sched/sched.h:1526 [inline] (P) > finish_lock_switch+0xc0/0x1e4 kernel/sched/core.c:5123 (P) > raw_spin_rq_unlock_irq kernel/sched/sched.h:1526 [inline] (L) > finish_lock_switch+0xbc/0x1e4 kernel/sched/core.c:5123 (L) > finish_task_switch+0x120/0x608 kernel/sched/core.c:5241 > context_switch kernel/sched/core.c:5372 [inline] > __schedule+0x1748/0x27f0 kernel/sched/core.c:6756 > preempt_schedule_irq+0x80/0x188 kernel/sched/core.c:7078 > arm64_preempt_schedule_irq arch/arm64/kernel/entry-common.c:301 [inline] > __el1_irq arch/arm64/kernel/entry-common.c:563 [inline] > el1_interrupt+0x4c/0x68 arch/arm64/kernel/entry-common.c:575 > el1h_64_irq_handler+0x18/0x24 arch/arm64/kernel/entry-common.c:580 > el1h_64_irq+0x6c/0x70 arch/arm64/kernel/entry.S:596 > __daif_local_irq_enable arch/arm64/include/asm/irqflags.h:26 [inline] (P) > arch_local_irq_enable arch/arm64/include/asm/irqflags.h:48 [inline] (P) > do_notify_resume+0x5c/0x1f4 arch/arm64/kernel/entry-common.c:133 (P) > do_notify_resume+0x58/0x1f4 arch/arm64/kernel/entry-common.c:133 (L) > exit_to_user_mode_prepare arch/arm64/kernel/entry-common.c:169 [inline] > exit_to_user_mode arch/arm64/kernel/entry-common.c:178 [inline] > el0_interrupt+0xc8/0x248 arch/arm64/kernel/entry-common.c:832 > __el0_irq_handler_common+0x18/0x24 arch/arm64/kernel/entry-common.c:837 > el0t_64_irq_handler+0x10/0x1c arch/arm64/kernel/entry-common.c:842 > el0t_64_irq+0x198/0x19c arch/arm64/kernel/entry.S:601 > irq event stamp: 35689 > hardirqs last enabled at (35688): [<ffff80008b687f2c>] __exit_to_kernel_mode arch/arm64/kernel/entry-common.c:85 [inline] > hardirqs last enabled at (35688): [<ffff80008b687f2c>] exit_to_kernel_mode+0xdc/0x10c arch/arm64/kernel/entry-common.c:95 > hardirqs last disabled at (35689): [<ffff80008b6a9b44>] __raw_spin_lock_irq include/linux/spinlock_api_smp.h:117 [inline] > hardirqs last disabled at (35689): [<ffff80008b6a9b44>] _raw_spin_lock_irq+0x28/0x70 kernel/locking/spinlock.c:170 > softirqs last enabled at (34558): [<ffff800080129934>] local_bh_enable+0x10/0x34 include/linux/bottom_half.h:32 > softirqs last disabled at (35685): [<ffff800080020db4>] __do_softirq+0x14/0x20 kernel/softirq.c:588 > ---[ end trace 0000000000000000 ]--- > > > --- > If you want syzbot to run the reproducer, reply with: > #syz test: git://repo/address.git branch-or-commit-hash > If you attach or paste a git patch, syzbot will apply it before testing.
