INFO: task syz-executor1:11180 blocked for more than 120 seconds. Not tainted 4.15.0-rc7+ #256 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor1 D24192 11180 3731 0x00000004 Call Trace: context_switch kernel/sched/core.c:2799 [inline] __schedule+0x8eb/0x2060 kernel/sched/core.c:3375 schedule+0xf5/0x430 kernel/sched/core.c:3434 schedule_preempt_disabled+0x10/0x20 kernel/sched/core.c:3492 __mutex_lock_common kernel/locking/mutex.c:833 [inline] __mutex_lock+0xaad/0x1a80 kernel/locking/mutex.c:893 mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:908 snd_pcm_oss_write1 sound/core/oss/pcm_oss.c:1338 [inline] snd_pcm_oss_write+0x22d/0x830 sound/core/oss/pcm_oss.c:2646 do_loop_readv_writev fs/read_write.c:676 [inline] do_iter_write+0x3ca/0x540 fs/read_write.c:934 vfs_writev+0x18a/0x340 fs/read_write.c:977 do_writev+0xfc/0x2a0 fs/read_write.c:1012 SYSC_writev fs/read_write.c:1085 [inline] SyS_writev+0x27/0x30 fs/read_write.c:1082 entry_SYSCALL_64_fastpath+0x23/0x9a RIP: 0033:0x452ac9 RSP: 002b:00007fca929efc58 EFLAGS: 00000212 ORIG_RAX: 0000000000000014 RAX: ffffffffffffffda RBX: 000000000071bf58 RCX: 0000000000452ac9 RDX: 0000000000000005 RSI: 0000000020d30fb0 RDI: 0000000000000014 RBP: 00000000000003aa R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000212 R12: 00000000006f3890 R13: 00000000ffffffff R14: 00007fca929f06d4 R15: 0000000000000005 Showing all locks held in the system: 2 locks held by khungtaskd/737: #0: (rcu_read_lock){....}, at: [<00000000eaa2e968>] check_hung_uninterruptible_tasks kernel/hung_task.c:175 [inline] #0: (rcu_read_lock){....}, at: [<00000000eaa2e968>] watchdog+0x1c5/0xd60 kernel/hung_task.c:249 #1: (tasklist_lock){.+.+}, at: [<000000005ed461f9>] debug_show_all_locks+0xd3/0x400 kernel/locking/lockdep.c:4464 2 locks held by getty/3468: #0: (&tty->ldisc_sem){++++}, at: [<000000000ce218db>] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: (&ldata->atomic_read_lock){+.+.}, at: [<0000000093a88874>] n_tty_read+0x2ef/0x1a00 drivers/tty/n_tty.c:2131 2 locks held by getty/3469: #0: (&tty->ldisc_sem){++++}, at: [<000000000ce218db>] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: (&ldata->atomic_read_lock){+.+.}, at: [<0000000093a88874>] n_tty_read+0x2ef/0x1a00 drivers/tty/n_tty.c:2131 2 locks held by getty/3470: #0: (&tty->ldisc_sem){++++}, at: [<000000000ce218db>] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: (&ldata->atomic_read_lock){+.+.}, at: [<0000000093a88874>] n_tty_read+0x2ef/0x1a00 drivers/tty/n_tty.c:2131 2 locks held by getty/3471: #0: (&tty->ldisc_sem){++++}, at: [<000000000ce218db>] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: (&ldata->atomic_read_lock){+.+.}, at: [<0000000093a88874>] n_tty_read+0x2ef/0x1a00 drivers/tty/n_tty.c:2131 2 locks held by getty/3472: #0: (&tty->ldisc_sem){++++}, at: [<000000000ce218db>] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: (&ldata->atomic_read_lock){+.+.}, at: [<0000000093a88874>] n_tty_read+0x2ef/0x1a00 drivers/tty/n_tty.c:2131 2 locks held by getty/3473: #0: (&tty->ldisc_sem){++++}, at: [<000000000ce218db>] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: (&ldata->atomic_read_lock){+.+.}, at: [<0000000093a88874>] n_tty_read+0x2ef/0x1a00 drivers/tty/n_tty.c:2131 2 locks held by getty/3474: #0: (&tty->ldisc_sem){++++}, at: [<000000000ce218db>] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: (&ldata->atomic_read_lock){+.+.}, at: [<0000000093a88874>] n_tty_read+0x2ef/0x1a00 drivers/tty/n_tty.c:2131 1 lock held by syz-executor1/11180: #0: (&runtime->oss.params_lock){+.+.}, at: [<0000000025c7b14d>] snd_pcm_oss_write1 sound/core/oss/pcm_oss.c:1338 [inline] #0: (&runtime->oss.params_lock){+.+.}, at: [<0000000025c7b14d>] snd_pcm_oss_write+0x22d/0x830 sound/core/oss/pcm_oss.c:2646 1 lock held by syz-executor3/11468: #0: (net_mutex){+.+.}, at: [<0000000012aa0ea7>] copy_net_ns+0x239/0x580 net/core/net_namespace.c:410 1 lock held by syz-executor5/11495: #0: (net_mutex){+.+.}, at: [<0000000012aa0ea7>] copy_net_ns+0x239/0x580 net/core/net_namespace.c:410 1 lock held by syz-executor0/11515: #0: (net_mutex){+.+.}, at: [<0000000012aa0ea7>] copy_net_ns+0x239/0x580 net/core/net_namespace.c:410 ============================================= NMI backtrace for cpu 0 CPU: 0 PID: 737 Comm: khungtaskd Not tainted 4.15.0-rc7+ #256 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:17 [inline] dump_stack+0x194/0x257 lib/dump_stack.c:53 nmi_cpu_backtrace+0x1d2/0x210 lib/nmi_backtrace.c:103 nmi_trigger_cpumask_backtrace+0x122/0x180 lib/nmi_backtrace.c:62 arch_trigger_cpumask_backtrace+0x14/0x20 arch/x86/kernel/apic/hw_nmi.c:38 trigger_all_cpu_backtrace include/linux/nmi.h:138 [inline] check_hung_task kernel/hung_task.c:132 [inline] check_hung_uninterruptible_tasks kernel/hung_task.c:190 [inline] watchdog+0x90c/0xd60 kernel/hung_task.c:249 kthread+0x33c/0x400 kernel/kthread.c:238 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:524 Sending NMI from CPU 0 to CPUs 1: NMI backtrace for cpu 1 CPU: 1 PID: 11167 Comm: syz-executor1 Not tainted 4.15.0-rc7+ #256 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 RIP: 0010:check_kcov_mode kernel/kcov.c:67 [inline] RIP: 0010:__sanitizer_cov_trace_pc+0x1a/0x50 kernel/kcov.c:101 RSP: 0018:ffff8801cfeb77d0 EFLAGS: 00000246 RAX: ffff8801cb2c23c0 RBX: ffffc900012ff9c5 RCX: 0000000000000007 RDX: 0000000000000000 RSI: ffffc900020b7000 RDI: ffffc9000126438a RBP: ffff8801cfeb77d0 R08: fffff5200024c872 R09: fffff5200024c872 R10: 0000000000000001 R11: fffff5200024c871 R12: 0000000000007e00 R13: ffff8801d8a3a900 R14: dffffc0000000000 R15: ffffc9000126438a FS: 00007fca92a11700(0000) GS:ffff8801db300000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000020eef000 CR3: 00000001d477e002 CR4: 00000000001606e0 Call Trace: ulaw2linear sound/core/oss/mulaw.c:134 [inline] mulaw_decode+0x5aa/0x770 sound/core/oss/mulaw.c:194 mulaw_transfer+0x222/0x270 sound/core/oss/mulaw.c:273 snd_pcm_plug_write_transfer+0x22d/0x420 sound/core/oss/pcm_plugin.c:611 snd_pcm_oss_write2+0x260/0x420 sound/core/oss/pcm_oss.c:1311 snd_pcm_oss_write1 sound/core/oss/pcm_oss.c:1372 [inline] snd_pcm_oss_write+0x5fe/0x830 sound/core/oss/pcm_oss.c:2646 do_loop_readv_writev fs/read_write.c:676 [inline] do_iter_write+0x3ca/0x540 fs/read_write.c:934 vfs_writev+0x18a/0x340 fs/read_write.c:977 do_writev+0xfc/0x2a0 fs/read_write.c:1012 SYSC_writev fs/read_write.c:1085 [inline] SyS_writev+0x27/0x30 fs/read_write.c:1082 entry_SYSCALL_64_fastpath+0x23/0x9a RIP: 0033:0x452ac9 RSP: 002b:00007fca92a10c58 EFLAGS: 00000212 ORIG_RAX: 0000000000000014 RAX: ffffffffffffffda RBX: 00007fca92a11700 RCX: 0000000000452ac9 RDX: 0000000000000005 RSI: 0000000020d30fb0 RDI: 0000000000000014 RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000212 R12: 0000000000000000 R13: 0000000000a2f7ef R14: 00007fca92a119c0 R15: 0000000000000000 Code: e9 c3 fc ff ff 90 90 90 90 90 90 90 90 90 90 90 90 55 65 48 8b 04 25 c0 ed 01 00 48 89 e5 65 8b 15 bc d5 91 7e 81 e2 00 01 1f 00 <48> 8b 4d 08 75 2b 8b 90 b8 12 00 00 83 fa 02 75 20 48 8b b0 c0