audit: type=1400 audit(1521908506.964:249): avc: denied { getattr } for pid=27605 comm="syz-executor2" name="NETLINK" dev="sockfs" ino=86296 scontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tcontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tclass=netlink_generic_socket permissive=1 Buffer I/O error on dev loop0, logical block 3, async page read INFO: task syz-executor2:27613 blocked for more than 120 seconds. Not tainted 4.16.0-rc6+ #364 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor2 D23232 27613 4293 0x00000004 Call Trace: context_switch kernel/sched/core.c:2862 [inline] __schedule+0x8fb/0x1ec0 kernel/sched/core.c:3440 schedule+0xf5/0x430 kernel/sched/core.c:3499 io_schedule+0x1c/0x70 kernel/sched/core.c:5115 wait_on_page_bit_common+0x4b3/0x770 mm/filemap.c:1099 wait_on_page_bit mm/filemap.c:1132 [inline] wait_on_page_writeback include/linux/pagemap.h:546 [inline] __filemap_fdatawait_range+0x282/0x430 mm/filemap.c:533 filemap_fdatawait_keep_errors+0x2a/0xb0 mm/filemap.c:600 fdatawait_one_bdev+0x50/0x70 fs/sync.c:95 iterate_bdevs+0x109/0x260 fs/block_dev.c:2162 sys_sync+0x120/0x1c0 fs/sync.c:117 do_syscall_64+0x281/0x940 arch/x86/entry/common.c:287 entry_SYSCALL_64_after_hwframe+0x42/0xb7 RIP: 0033:0x454239 RSP: 002b:00007f4154293c68 EFLAGS: 00000246 ORIG_RAX: 00000000000000a2 RAX: ffffffffffffffda RBX: 00007f41542946d4 RCX: 0000000000454239 RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000 RBP: 000000000072bea0 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff R13: 000000000000061d R14: 00000000006fa358 R15: 0000000000000000 Showing all locks held in the system: 2 locks held by khungtaskd/801: #0: (rcu_read_lock){....}, at: [<00000000fa91f797>] check_hung_uninterruptible_tasks kernel/hung_task.c:175 [inline] #0: (rcu_read_lock){....}, at: [<00000000fa91f797>] watchdog+0x1c5/0xd60 kernel/hung_task.c:249 #1: (tasklist_lock){.+.+}, at: [<00000000036387be>] debug_show_all_locks+0xd3/0x3d0 kernel/locking/lockdep.c:4470 2 locks held by getty/4213: #0: (&tty->ldisc_sem){++++}, at: [<00000000d8d29e13>] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: (&ldata->atomic_read_lock){+.+.}, at: [<00000000d4344148>] n_tty_read+0x2ef/0x1a40 drivers/tty/n_tty.c:2131 2 locks held by getty/4214: #0: (&tty->ldisc_sem){++++}, at: [<00000000d8d29e13>] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: (&ldata->atomic_read_lock){+.+.}, at: [<00000000d4344148>] n_tty_read+0x2ef/0x1a40 drivers/tty/n_tty.c:2131 2 locks held by getty/4215: #0: (&tty->ldisc_sem){++++}, at: [<00000000d8d29e13>] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: (&ldata->atomic_read_lock){+.+.}, at: [<00000000d4344148>] n_tty_read+0x2ef/0x1a40 drivers/tty/n_tty.c:2131 2 locks held by getty/4216: #0: (&tty->ldisc_sem){++++}, at: [<00000000d8d29e13>] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: (&ldata->atomic_read_lock){+.+.}, at: [<00000000d4344148>] n_tty_read+0x2ef/0x1a40 drivers/tty/n_tty.c:2131 2 locks held by getty/4217: #0: (&tty->ldisc_sem){++++}, at: [<00000000d8d29e13>] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: (&ldata->atomic_read_lock){+.+.}, at: [<00000000d4344148>] n_tty_read+0x2ef/0x1a40 drivers/tty/n_tty.c:2131 2 locks held by getty/4218: #0: (&tty->ldisc_sem){++++}, at: [<00000000d8d29e13>] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: (&ldata->atomic_read_lock){+.+.}, at: [<00000000d4344148>] n_tty_read+0x2ef/0x1a40 drivers/tty/n_tty.c:2131 2 locks held by getty/4219: #0: (&tty->ldisc_sem){++++}, at: [<00000000d8d29e13>] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: (&ldata->atomic_read_lock){+.+.}, at: [<00000000d4344148>] n_tty_read+0x2ef/0x1a40 drivers/tty/n_tty.c:2131 3 locks held by kworker/u4:6/8458: #0: ((wq_completion)"writeback"){+.+.}, at: [<00000000af7fce96>] work_static include/linux/workqueue.h:198 [inline] #0: ((wq_completion)"writeback"){+.+.}, at: [<00000000af7fce96>] set_work_data kernel/workqueue.c:619 [inline] #0: ((wq_completion)"writeback"){+.+.}, at: [<00000000af7fce96>] set_work_pool_and_clear_pending kernel/workqueue.c:646 [inline] #0: ((wq_completion)"writeback"){+.+.}, at: [<00000000af7fce96>] process_one_work+0xb12/0x1bb0 kernel/workqueue.c:2084 #1: ((work_completion)(&(&wb->dwork)->work)){+.+.}, at: [<000000002f3bc892>] process_one_work+0xb89/0x1bb0 kernel/workqueue.c:2088 #2: (&type->s_umount_key#27){.+.+}, at: [<00000000f7d3a137>] trylock_super+0x20/0x100 fs/super.c:395 1 lock held by blkid/26997: #0: (&bdev->bd_mutex){+.+.}, at: [<00000000a3f0c598>] blkdev_put+0x2a/0x4f0 fs/block_dev.c:1808 1 lock held by syz-executor2/27613: #0: (&bdev->bd_mutex){+.+.}, at: [<00000000345ab015>] iterate_bdevs+0xc8/0x260 fs/block_dev.c:2160 1 lock held by syz-executor2/27623: #0: (&bdev->bd_mutex){+.+.}, at: [<00000000345ab015>] iterate_bdevs+0xc8/0x260 fs/block_dev.c:2160 ============================================= NMI backtrace for cpu 1 CPU: 1 PID: 801 Comm: khungtaskd Not tainted 4.16.0-rc6+ #364 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+0x194/0x24d lib/dump_stack.c:53 nmi_cpu_backtrace+0x1d2/0x210 lib/nmi_backtrace.c:103 nmi_trigger_cpumask_backtrace+0x123/0x180 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+0x3a/0x50 arch/x86/entry/entry_64.S:406 Sending NMI from CPU 1 to CPUs 0: NMI backtrace for cpu 0 skipped: idling at native_safe_halt+0x6/0x10 arch/x86/include/asm/irqflags.h:54