On Fri, 04 Mar 2022 06:46:26 -0800

syzbot has found a reproducer for the following issue on:

HEAD commit: 38f80f42147f MAINTAINERS: Remove dead patchwork link git tree: upstream console output: https://syzkaller.appspot.com/x/log.txt?x=161736d6700000 kernel config: https://syzkaller.appspot.com/x/.config?x=4e9585407e09f75f dashboard link: https://syzkaller.appspot.com/bug?extid=1ee0910eca9c94f71f25 compiler: gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2 syz repro: https://syzkaller.appspot.com/x/repro.syz?x=11b6ad85700000 C reproducer: https://syzkaller.appspot.com/x/repro.c?x=12527ef1700000

IMPORTANT: if you fix the issue, please add the following tag to the commit: Reported-by: syzbot+1ee0910eca9c94f71f25@syzkaller.appspotmail.com

======================================================== WARNING: possible irq lock inversion dependency detected 5.17.0-rc6-syzkaller-00184-g38f80f42147f #0 Not tainted

---

syz-executor301/4486 just changed the state of lock: ffff88814a78a948 (&timer->lock){..-.}-{2:2}, at: snd_timer_interrupt.part.0+0x34/0xcf0 sound/core/timer.c:856 but this lock took another, SOFTIRQ-READ-unsafe lock in the past: (tasklist_lock){.+.+}-{2:2}

and interrupts could create inverse lock ordering between them.

other info that might help us debug this: Chain exists of: &timer->lock --> &new->fa_lock --> tasklist_lock

Possible interrupt unsafe locking scenario:

   CPU0                    CPU1
   ----                    ----

lock(tasklist_lock); local_irq_disable(); lock(&timer->lock); lock(&new->fa_lock);

<Interrupt> lock(&timer->lock);

*** DEADLOCK ***

1 lock held by syz-executor301/4486: #0: ffffc90000007d70 ((&priv->tlist)){+.-.}-{0:0}, at: lockdep_copy_map include/linux/lockdep.h:35 [inline] #0: ffffc90000007d70 ((&priv->tlist)){+.-.}-{0:0}, at: call_timer_fn+0xd5/0x6b0 kernel/time/timer.c:1411

the shortest dependencies between 2nd lock and 1st lock: -> (tasklist_lock){.+.+}-{2:2} { HARDIRQ-ON-R at: lock_acquire kernel/locking/lockdep.c:5639 [inline] lock_acquire+0x1ab/0x510 kernel/locking/lockdep.c:5604 __raw_read_lock include/linux/rwlock_api_smp.h:150 [inline] _raw_read_lock+0x5b/0x70 kernel/locking/spinlock.c:228 do_wait+0x284/0xce0 kernel/exit.c:1518 kernel_wait+0x9c/0x150 kernel/exit.c:1708 call_usermodehelper_exec_sync kernel/umh.c:139 [inline] call_usermodehelper_exec_work+0xf5/0x180 kernel/umh.c:166 process_one_work+0x9ac/0x1650 kernel/workqueue.c:2307 worker_thread+0x657/0x1110 kernel/workqueue.c:2454 kthread+0x2e9/0x3a0 kernel/kthread.c:377 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295 SOFTIRQ-ON-R at: lock_acquire kernel/locking/lockdep.c:5639 [inline] lock_acquire+0x1ab/0x510 kernel/locking/lockdep.c:5604 __raw_read_lock include/linux/rwlock_api_smp.h:150 [inline] _raw_read_lock+0x5b/0x70 kernel/locking/spinlock.c:228 do_wait+0x284/0xce0 kernel/exit.c:1518 kernel_wait+0x9c/0x150 kernel/exit.c:1708 call_usermodehelper_exec_sync kernel/umh.c:139 [inline] call_usermodehelper_exec_work+0xf5/0x180 kernel/umh.c:166 process_one_work+0x9ac/0x1650 kernel/workqueue.c:2307 worker_thread+0x657/0x1110 kernel/workqueue.c:2454 kthread+0x2e9/0x3a0 kernel/kthread.c:377 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295 INITIAL USE at: lock_acquire kernel/locking/lockdep.c:5639 [inline] lock_acquire+0x1ab/0x510 kernel/locking/lockdep.c:5604 __raw_write_lock_irq include/linux/rwlock_api_smp.h:195 [inline] _raw_write_lock_irq+0x32/0x50 kernel/locking/spinlock.c:326 copy_process+0x486a/0x7250 kernel/fork.c:2295 kernel_clone+0xe7/0xab0 kernel/fork.c:2565 kernel_thread+0xb5/0xf0 kernel/fork.c:2617 rest_init+0x23/0x3e0 init/main.c:690 start_kernel+0x47a/0x49b init/main.c:1138 secondary_startup_64_no_verify+0xc3/0xcb INITIAL READ USE at: lock_acquire kernel/locking/lockdep.c:5639 [inline] lock_acquire+0x1ab/0x510 kernel/locking/lockdep.c:5604 __raw_read_lock include/linux/rwlock_api_smp.h:150 [inline] _raw_read_lock+0x5b/0x70 kernel/locking/spinlock.c:228 do_wait+0x284/0xce0 kernel/exit.c:1518 kernel_wait+0x9c/0x150 kernel/exit.c:1708 call_usermodehelper_exec_sync kernel/umh.c:139 [inline] call_usermodehelper_exec_work+0xf5/0x180 kernel/umh.c:166 process_one_work+0x9ac/0x1650 kernel/workqueue.c:2307 worker_thread+0x657/0x1110 kernel/workqueue.c:2454 kthread+0x2e9/0x3a0 kernel/kthread.c:377 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295 } ... key at: [<ffffffff8b80a098>] tasklist_lock+0x18/0x40 ... acquired at: __raw_read_lock include/linux/rwlock_api_smp.h:150 [inline] _raw_read_lock+0x5b/0x70 kernel/locking/spinlock.c:228 send_sigio+0xab/0x380 fs/fcntl.c:810 kill_fasync_rcu fs/fcntl.c:1021 [inline] kill_fasync fs/fcntl.c:1035 [inline] kill_fasync+0x1f8/0x470 fs/fcntl.c:1028 snd_timer_user_ccallback+0x298/0x330 sound/core/timer.c:1386 snd_timer_notify1+0x11c/0x3b0 sound/core/timer.c:516 snd_timer_stop1+0x496/0x860 sound/core/timer.c:657 snd_timer_stop sound/core/timer.c:710 [inline] snd_timer_close_locked+0x20f/0xbb0 sound/core/timer.c:408 snd_timer_close+0x87/0xf0 sound/core/timer.c:463 __snd_timer_user_ioctl.isra.0+0x10e2/0x2490 sound/core/timer.c:1762 snd_timer_user_ioctl+0x77/0xb0 sound/core/timer.c:2128 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:874 [inline] __se_sys_ioctl fs/ioctl.c:860 [inline] __x64_sys_ioctl+0x193/0x200 fs/ioctl.c:860 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x44/0xae

-> (&f->f_owner.lock){....}-{2:2} { INITIAL USE at: lock_acquire kernel/locking/lockdep.c:5639 [inline] lock_acquire+0x1ab/0x510 kernel/locking/lockdep.c:5604 __raw_write_lock_irq include/linux/rwlock_api_smp.h:195 [inline] _raw_write_lock_irq+0x32/0x50 kernel/locking/spinlock.c:326 f_modown+0x2a/0x390 fs/fcntl.c:91 __f_setown fs/fcntl.c:110 [inline] f_setown+0xd7/0x230 fs/fcntl.c:138 do_fcntl+0x749/0x1210 fs/fcntl.c:393 __do_sys_fcntl fs/fcntl.c:472 [inline] __se_sys_fcntl fs/fcntl.c:457 [inline] __x64_sys_fcntl+0x165/0x1e0 fs/fcntl.c:457 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x44/0xae INITIAL READ USE at: lock_acquire kernel/locking/lockdep.c:5639 [inline] lock_acquire+0x1ab/0x510 kernel/locking/lockdep.c:5604 __raw_read_lock_irqsave include/linux/rwlock_api_smp.h:160 [inline] _raw_read_lock_irqsave+0x70/0x90 kernel/locking/spinlock.c:236 send_sigio+0x24/0x380 fs/fcntl.c:796 kill_fasync_rcu fs/fcntl.c:1021 [inline] kill_fasync fs/fcntl.c:1035 [inline] kill_fasync+0x1f8/0x470 fs/fcntl.c:1028 snd_timer_user_ccallback+0x298/0x330 sound/core/timer.c:1386 snd_timer_notify1+0x11c/0x3b0 sound/core/timer.c:516 snd_timer_start1+0x4d4/0x800 sound/core/timer.c:578 snd_timer_start sound/core/timer.c:696 [inline] snd_timer_start sound/core/timer.c:689 [inline] snd_timer_user_start.isra.0+0x1e3/0x260 sound/core/timer.c:1984 __snd_timer_user_ioctl.isra.0+0xda8/0x2490 sound/core/timer.c:2107 snd_timer_user_ioctl+0x77/0xb0 sound/core/timer.c:2128 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:874 [inline] __se_sys_ioctl fs/ioctl.c:860 [inline] __x64_sys_ioctl+0x193/0x200 fs/ioctl.c:860 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x44/0xae } ... key at: [<ffffffff90585a40>] __key.5+0x0/0x40 ... acquired at: __raw_read_lock_irqsave include/linux/rwlock_api_smp.h:160 [inline] _raw_read_lock_irqsave+0x70/0x90 kernel/locking/spinlock.c:236 send_sigio+0x24/0x380 fs/fcntl.c:796 kill_fasync_rcu fs/fcntl.c:1021 [inline] kill_fasync fs/fcntl.c:1035 [inline] kill_fasync+0x1f8/0x470 fs/fcntl.c:1028 snd_timer_user_ccallback+0x298/0x330 sound/core/timer.c:1386 snd_timer_notify1+0x11c/0x3b0 sound/core/timer.c:516 snd_timer_start1+0x4d4/0x800 sound/core/timer.c:578 snd_timer_start sound/core/timer.c:696 [inline] snd_timer_start sound/core/timer.c:689 [inline] snd_timer_user_start.isra.0+0x1e3/0x260 sound/core/timer.c:1984 __snd_timer_user_ioctl.isra.0+0xda8/0x2490 sound/core/timer.c:2107 snd_timer_user_ioctl+0x77/0xb0 sound/core/timer.c:2128 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:874 [inline] __se_sys_ioctl fs/ioctl.c:860 [inline] __x64_sys_ioctl+0x193/0x200 fs/ioctl.c:860 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x44/0xae

-> (&new->fa_lock){....}-{2:2} { INITIAL USE at: lock_acquire kernel/locking/lockdep.c:5639 [inline] lock_acquire+0x1ab/0x510 kernel/locking/lockdep.c:5604 __raw_write_lock_irq include/linux/rwlock_api_smp.h:195 [inline] _raw_write_lock_irq+0x32/0x50 kernel/locking/spinlock.c:326 fasync_remove_entry+0xb6/0x1f0 fs/fcntl.c:891 fasync_helper+0x9e/0xb0 fs/fcntl.c:994 __fput+0x846/0x9f0 fs/file_table.c:314 task_work_run+0xdd/0x1a0 kernel/task_work.c:164 exit_task_work include/linux/task_work.h:32 [inline] do_exit+0xb29/0x2a30 kernel/exit.c:806 do_group_exit+0xd2/0x2f0 kernel/exit.c:935 __do_sys_exit_group kernel/exit.c:946 [inline] __se_sys_exit_group kernel/exit.c:944 [inline] __x64_sys_exit_group+0x3a/0x50 kernel/exit.c:944 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x44/0xae INITIAL READ USE at: lock_acquire kernel/locking/lockdep.c:5639 [inline] lock_acquire+0x1ab/0x510 kernel/locking/lockdep.c:5604 __raw_read_lock_irqsave include/linux/rwlock_api_smp.h:160 [inline] _raw_read_lock_irqsave+0x70/0x90 kernel/locking/spinlock.c:236 kill_fasync_rcu fs/fcntl.c:1014 [inline] kill_fasync fs/fcntl.c:1035 [inline] kill_fasync+0x136/0x470 fs/fcntl.c:1028 snd_timer_user_ccallback+0x298/0x330 sound/core/timer.c:1386 snd_timer_notify1+0x11c/0x3b0 sound/core/timer.c:516 snd_timer_start1+0x4d4/0x800 sound/core/timer.c:578 snd_timer_start sound/core/timer.c:696 [inline] snd_timer_start sound/core/timer.c:689 [inline] snd_timer_user_start.isra.0+0x1e3/0x260 sound/core/timer.c:1984 __snd_timer_user_ioctl.isra.0+0xda8/0x2490 sound/core/timer.c:2107 snd_timer_user_ioctl+0x77/0xb0 sound/core/timer.c:2128 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:874 [inline] __se_sys_ioctl fs/ioctl.c:860 [inline] __x64_sys_ioctl+0x193/0x200 fs/ioctl.c:860 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x44/0xae } ... key at: [<ffffffff90586820>] __key.0+0x0/0x40 ... acquired at: __raw_read_lock_irqsave include/linux/rwlock_api_smp.h:160 [inline] _raw_read_lock_irqsave+0x70/0x90 kernel/locking/spinlock.c:236 kill_fasync_rcu fs/fcntl.c:1014 [inline] kill_fasync fs/fcntl.c:1035 [inline] kill_fasync+0x136/0x470 fs/fcntl.c:1028 snd_timer_user_ccallback+0x298/0x330 sound/core/timer.c:1386 snd_timer_notify1+0x11c/0x3b0 sound/core/timer.c:516 snd_timer_start1+0x4d4/0x800 sound/core/timer.c:578 snd_timer_start sound/core/timer.c:696 [inline] snd_timer_start sound/core/timer.c:689 [inline] snd_timer_user_start.isra.0+0x1e3/0x260 sound/core/timer.c:1984 __snd_timer_user_ioctl.isra.0+0xda8/0x2490 sound/core/timer.c:2107 snd_timer_user_ioctl+0x77/0xb0 sound/core/timer.c:2128 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:874 [inline] __se_sys_ioctl fs/ioctl.c:860 [inline] __x64_sys_ioctl+0x193/0x200 fs/ioctl.c:860 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x44/0xae

-> (&timer->lock){..-.}-{2:2} { IN-SOFTIRQ-W at: lock_acquire kernel/locking/lockdep.c:5639 [inline] lock_acquire+0x1ab/0x510 kernel/locking/lockdep.c:5604 __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline] _raw_spin_lock_irqsave+0x39/0x50 kernel/locking/spinlock.c:162 snd_timer_interrupt.part.0+0x34/0xcf0 sound/core/timer.c:856 snd_timer_interrupt sound/core/timer.c:1154 [inline] snd_timer_s_function+0x14b/0x200 sound/core/timer.c:1154 call_timer_fn+0x1a5/0x6b0 kernel/time/timer.c:1421 expire_timers kernel/time/timer.c:1466 [inline] __run_timers.part.0+0x67c/0xa30 kernel/time/timer.c:1734 __run_timers kernel/time/timer.c:1715 [inline] run_timer_softirq+0xb3/0x1d0 kernel/time/timer.c:1747 __do_softirq+0x29b/0x9c2 kernel/softirq.c:558 invoke_softirq kernel/softirq.c:432 [inline] __irq_exit_rcu+0x123/0x180 kernel/softirq.c:637 irq_exit_rcu+0x5/0x20 kernel/softirq.c:649 sysvec_apic_timer_interrupt+0x93/0xc0 arch/x86/kernel/apic/apic.c:1097 asm_sysvec_apic_timer_interrupt+0x12/0x20 arch/x86/include/asm/idtentry.h:638 bytes_is_nonzero mm/kasan/generic.c:85 [inline] memory_is_nonzero mm/kasan/generic.c:102 [inline] memory_is_poisoned_n mm/kasan/generic.c:128 [inline] memory_is_poisoned mm/kasan/generic.c:159 [inline] check_region_inline mm/kasan/generic.c:180 [inline] kasan_check_range+0xde/0x180 mm/kasan/generic.c:189 instrument_atomic_read include/linux/instrumented.h:71 [inline] atomic_long_read include/linux/atomic/atomic-instrumented.h:1265 [inline] filp_close+0x22/0x170 fs/open.c:1318 close_files fs/file.c:403 [inline] put_files_struct fs/file.c:418 [inline] put_files_struct+0x1d0/0x350 fs/file.c:415 exit_files+0x7e/0xa0 fs/file.c:435 do_exit+0xaf2/0x2a30 kernel/exit.c:801 do_group_exit+0xd2/0x2f0 kernel/exit.c:935 __do_sys_exit_group kernel/exit.c:946 [inline] __se_sys_exit_group kernel/exit.c:944 [inline] __x64_sys_exit_group+0x3a/0x50 kernel/exit.c:944 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x44/0xae INITIAL USE at: lock_acquire kernel/locking/lockdep.c:5639 [inline] lock_acquire+0x1ab/0x510 kernel/locking/lockdep.c:5604 __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline] _raw_spin_lock_irqsave+0x39/0x50 kernel/locking/spinlock.c:162 snd_timer_stop1+0x5c/0x860 sound/core/timer.c:626 snd_timer_stop sound/core/timer.c:710 [inline] snd_timer_user_start.isra.0+0x8b/0x260 sound/core/timer.c:1981 __snd_timer_user_ioctl.isra.0+0xda8/0x2490 sound/core/timer.c:2107 snd_timer_user_ioctl+0x77/0xb0 sound/core/timer.c:2128 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:874 [inline] __se_sys_ioctl fs/ioctl.c:860 [inline] __x64_sys_ioctl+0x193/0x200 fs/ioctl.c:860 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x44/0xae } ... key at: [<ffffffff908843c0>] __key.12+0x0/0x40 ... acquired at: mark_lock kernel/locking/lockdep.c:4569 [inline] mark_usage kernel/locking/lockdep.c:4500 [inline] __lock_acquire+0x11e3/0x56c0 kernel/locking/lockdep.c:4981 lock_acquire kernel/locking/lockdep.c:5639 [inline] lock_acquire+0x1ab/0x510 kernel/locking/lockdep.c:5604 __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline] _raw_spin_lock_irqsave+0x39/0x50 kernel/locking/spinlock.c:162 snd_timer_interrupt.part.0+0x34/0xcf0 sound/core/timer.c:856 snd_timer_interrupt sound/core/timer.c:1154 [inline] snd_timer_s_function+0x14b/0x200 sound/core/timer.c:1154 call_timer_fn+0x1a5/0x6b0 kernel/time/timer.c:1421 expire_timers kernel/time/timer.c:1466 [inline] __run_timers.part.0+0x67c/0xa30 kernel/time/timer.c:1734 __run_timers kernel/time/timer.c:1715 [inline] run_timer_softirq+0xb3/0x1d0 kernel/time/timer.c:1747 __do_softirq+0x29b/0x9c2 kernel/softirq.c:558 invoke_softirq kernel/softirq.c:432 [inline] __irq_exit_rcu+0x123/0x180 kernel/softirq.c:637 irq_exit_rcu+0x5/0x20 kernel/softirq.c:649 sysvec_apic_timer_interrupt+0x93/0xc0 arch/x86/kernel/apic/apic.c:1097 asm_sysvec_apic_timer_interrupt+0x12/0x20 arch/x86/include/asm/idtentry.h:638 bytes_is_nonzero mm/kasan/generic.c:85 [inline] memory_is_nonzero mm/kasan/generic.c:102 [inline] memory_is_poisoned_n mm/kasan/generic.c:128 [inline] memory_is_poisoned mm/kasan/generic.c:159 [inline] check_region_inline mm/kasan/generic.c:180 [inline] kasan_check_range+0xde/0x180 mm/kasan/generic.c:189 instrument_atomic_read include/linux/instrumented.h:71 [inline] atomic_long_read include/linux/atomic/atomic-instrumented.h:1265 [inline] filp_close+0x22/0x170 fs/open.c:1318 close_files fs/file.c:403 [inline] put_files_struct fs/file.c:418 [inline] put_files_struct+0x1d0/0x350 fs/file.c:415 exit_files+0x7e/0xa0 fs/file.c:435 do_exit+0xaf2/0x2a30 kernel/exit.c:801 do_group_exit+0xd2/0x2f0 kernel/exit.c:935 __do_sys_exit_group kernel/exit.c:946 [inline] __se_sys_exit_group kernel/exit.c:944 [inline] __x64_sys_exit_group+0x3a/0x50 kernel/exit.c:944 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x44/0xae

stack backtrace: CPU: 0 PID: 4486 Comm: syz-executor301 Not tainted 5.17.0-rc6-syzkaller-00184-g38f80f42147f #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace:

<IRQ> __dump_stack lib/dump_stack.c:88 [inline] dump_stack_lvl+0xcd/0x134 lib/dump_stack.c:106 print_irq_inversion_bug kernel/locking/lockdep.c:194 [inline] check_usage_forwards kernel/locking/lockdep.c:4043 [inline] mark_lock_irq kernel/locking/lockdep.c:4175 [inline] mark_lock.part.0.cold+0x86/0xd8 kernel/locking/lockdep.c:4605 mark_lock kernel/locking/lockdep.c:4569 [inline] mark_usage kernel/locking/lockdep.c:4500 [inline] __lock_acquire+0x11e3/0x56c0 kernel/locking/lockdep.c:4981 lock_acquire kernel/locking/lockdep.c:5639 [inline] lock_acquire+0x1ab/0x510 kernel/locking/lockdep.c:5604 __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline] _raw_spin_lock_irqsave+0x39/0x50 kernel/locking/spinlock.c:162 snd_timer_interrupt.part.0+0x34/0xcf0 sound/core/timer.c:856 snd_timer_interrupt sound/core/timer.c:1154 [inline] snd_timer_s_function+0x14b/0x200 sound/core/timer.c:1154 call_timer_fn+0x1a5/0x6b0 kernel/time/timer.c:1421 expire_timers kernel/time/timer.c:1466 [inline] __run_timers.part.0+0x67c/0xa30 kernel/time/timer.c:1734 __run_timers kernel/time/timer.c:1715 [inline] run_timer_softirq+0xb3/0x1d0 kernel/time/timer.c:1747 __do_softirq+0x29b/0x9c2 kernel/softirq.c:558 invoke_softirq kernel/softirq.c:432 [inline] __irq_exit_rcu+0x123/0x180 kernel/softirq.c:637 irq_exit_rcu+0x5/0x20 kernel/softirq.c:649 sysvec_apic_timer_interrupt+0x93/0xc0 arch/x86/kernel/apic/apic.c:1097 </IRQ> <TASK> asm_sysvec_apic_timer_interrupt+0x12/0x20 arch/x86/include/asm/idtentry.h:638 RIP: 0010:bytes_is_nonzero mm/kasan/generic.c:85 [inline] RIP: 0010:memory_is_nonzero mm/kasan/generic.c:102 [inline] RIP: 0010:memory_is_poisoned_n mm/kasan/generic.c:128 [inline] RIP: 0010:memory_is_poisoned mm/kasan/generic.c:159 [inline] RIP: 0010:check_region_inline mm/kasan/generic.c:180 [inline] RIP: 0010:kasan_check_range+0xde/0x180 mm/kasan/generic.c:189 Code: 74 f2 48 89 c2 b8 01 00 00 00 48 85 d2 75 56 5b 5d 41 5c c3 48 85 d2 74 5e 48 01 ea eb 09 48 83 c0 01 48 39 d0 74 50 80 38 00 <74> f2 eb d4 41 bc 08 00 00 00 48 89 ea 45 29 dc 4d 8d 1c 2c eb 0c RSP: 0018:ffffc9000376fd30 EFLAGS: 00000246 RAX: ffffed100f1d3d9f RBX: ffffed100f1d3da0 RCX: ffffffff81cb24b2 RDX: ffffed100f1d3da0 RSI: 0000000000000008 RDI: ffff888078e9ecf8 RBP: ffffed100f1d3d9f R08: 0000000000000000 R09: ffff888078e9ecff R10: ffffed100f1d3d9f R11: 0000000000000000 R12: ffff88807ee70f00 R13: ffff888078e9ecf8 R14: ffff88807ee70f00 R15: ffff88807ee71028 instrument_atomic_read include/linux/instrumented.h:71 [inline] atomic_long_read include/linux/atomic/atomic-instrumented.h:1265 [inline] filp_close+0x22/0x170 fs/open.c:1318 close_files fs/file.c:403 [inline] put_files_struct fs/file.c:418 [inline] put_files_struct+0x1d0/0x350 fs/file.c:415 exit_files+0x7e/0xa0 fs/file.c:435 do_exit+0xaf2/0x2a30 kernel/exit.c:801 do_group_exit+0xd2/0x2f0 kernel/exit.c:935 __do_sys_exit_group kernel/exit.c:946 [inline] __se_sys_exit_group kernel/exit.c:944 [inline] __x64_sys_exit_group+0x3a/0x50 kernel/exit.c:944 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x44/0xae RIP: 0033:0x7ff95f986c99 Code: Unable to access opcode bytes at RIP 0x7ff95f986c6f. RSP: 002b:00007ffecd4a5e98 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7 RAX: ffffffffffffffda RBX: 00007ff95f9fb330 RCX: 00007ff95f986c99 RDX: 000000000000003c RSI: 00000000000000e7 RDI: 0000000000000000 RBP: 0000000000000000 R08: ffffffffffffffc0 R09: 0000000000000001 R10: 0000000000000001 R11: 0000000000000246 R12: 00007ff95f9fb330 R13: 0000000000000001 R14: 0000000000000000 R15: 0000000000000001 </TASK> ---------------- Code disassembly (best guess): 0: 74 f2 je 0xfffffff4 2: 48 89 c2 mov %rax,%rdx 5: b8 01 00 00 00 mov $0x1,%eax a: 48 85 d2 test %rdx,%rdx d: 75 56 jne 0x65 f: 5b pop %rbx 10: 5d pop %rbp 11: 41 5c pop %r12 13: c3 retq 14: 48 85 d2 test %rdx,%rdx 17: 74 5e je 0x77 19: 48 01 ea add %rbp,%rdx 1c: eb 09 jmp 0x27 1e: 48 83 c0 01 add $0x1,%rax 22: 48 39 d0 cmp %rdx,%rax 25: 74 50 je 0x77 27: 80 38 00 cmpb $0x0,(%rax) * 2a: 74 f2 je 0x1e <-- trapping instruction 2c: eb d4 jmp 0x2 2e: 41 bc 08 00 00 00 mov $0x8,%r12d 34: 48 89 ea mov %rbp,%rdx 37: 45 29 dc sub %r11d,%r12d 3a: 4d 8d 1c 2c lea (%r12,%rbp,1),%r11 3e: eb 0c jmp 0x4c

Walk around the deadlock by trying to lock tasklist_lock for write on timer irq and scheduling workqueue work if any lock owner detected.

Only for thoughts now.

Hillf

#syz test: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/ 38f80f42147f

--- x/sound/core/timer.c +++ y/sound/core/timer.c @@ -916,7 +916,14 @@ void snd_timer_interrupt(struct snd_time }

/* now process all fast callbacks */ - snd_timer_process_callbacks(timer, &timer->ack_list_head); + if (write_trylock(&tasklist_lock)) { + write_unlock(&tasklist_lock); + snd_timer_process_callbacks(timer, &timer->ack_list_head); + } else { + /* go the slow path to avoid deadlock by calling kill_fasync() */ + list_splice_init(&timer->ack_list_head, + &timer->sack_list_head); + }

/* do we have any slow callbacks? */ use_work = !list_empty(&timer->sack_list_head); --