INFO: task syz-executor2:14179 blocked for more than 120 seconds. Not tainted 4.15.0-rc3+ #132 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor2 D22920 14179 3396 0xa0020004 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 __rwsem_down_read_failed_common kernel/locking/rwsem-xadd.c:269 [inline] rwsem_down_read_failed+0x401/0x6e0 kernel/locking/rwsem-xadd.c:286 call_rwsem_down_read_failed+0x18/0x30 arch/x86/lib/rwsem.S:94 __down_read arch/x86/include/asm/rwsem.h:83 [inline] down_read+0xa4/0x150 kernel/locking/rwsem.c:26 exit_mm kernel/exit.c:510 [inline] do_exit+0x4b0/0x1ae0 kernel/exit.c:852 do_group_exit+0x149/0x400 kernel/exit.c:968 get_signal+0x73f/0x16c0 kernel/signal.c:2335 do_signal+0x94/0x1ee0 arch/x86/kernel/signal.c:809 exit_to_usermode_loop+0x214/0x310 arch/x86/entry/common.c:158 prepare_exit_to_usermode arch/x86/entry/common.c:195 [inline] syscall_return_slowpath arch/x86/entry/common.c:264 [inline] do_syscall_32_irqs_on arch/x86/entry/common.c:333 [inline] do_fast_syscall_32+0xbfd/0xf9d arch/x86/entry/common.c:389 entry_SYSENTER_compat+0x51/0x60 arch/x86/entry/entry_64_compat.S:125 RIP: 0023:0xf7f8fc79 RSP: 002b:000000000847f7ac EFLAGS: 00000246 ORIG_RAX: 00000000000000c0 RAX: fffffffffffffffc RBX: 0000000000000000 RCX: 0000000000021000 RDX: 0000000000000003 RSI: 0000000000020022 RDI: 00000000ffffffff RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000 R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000 Showing all locks held in the system: 2 locks held by khungtaskd/674: #0: (rcu_read_lock){....}, at: [<00000000c3230746>] check_hung_uninterruptible_tasks kernel/hung_task.c:175 [inline] #0: (rcu_read_lock){....}, at: [<00000000c3230746>] watchdog+0x1c5/0xd60 kernel/hung_task.c:249 #1: (tasklist_lock){.+.+}, at: [<00000000174d7dc0>] debug_show_all_locks+0xd3/0x400 kernel/locking/lockdep.c:4554 1 lock held by khugepaged/680: #0: (&mm->mmap_sem){++++}, at: [<00000000a95d3a96>] khugepaged_scan_mm_slot mm/khugepaged.c:1677 [inline] #0: (&mm->mmap_sem){++++}, at: [<00000000a95d3a96>] khugepaged_do_scan mm/khugepaged.c:1810 [inline] #0: (&mm->mmap_sem){++++}, at: [<00000000a95d3a96>] khugepaged+0x9d8/0x1400 mm/khugepaged.c:1855 1 lock held by rsyslogd/2997: #0: (&f->f_pos_lock){+.+.}, at: [<0000000015a34003>] __fdget_pos+0x131/0x1a0 fs/file.c:770 2 locks held by getty/3120: #0: (&tty->ldisc_sem){++++}, at: [<00000000d8b00b82>] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: (&ldata->atomic_read_lock){+.+.}, at: [<00000000159f44d6>] n_tty_read+0x2f2/0x1a10 drivers/tty/n_tty.c:2131 2 locks held by getty/3121: #0: (&tty->ldisc_sem){++++}, at: [<00000000d8b00b82>] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: (&ldata->atomic_read_lock){+.+.}, at: [<00000000159f44d6>] n_tty_read+0x2f2/0x1a10 drivers/tty/n_tty.c:2131 2 locks held by getty/3122: #0: (&tty->ldisc_sem){++++}, at: [<00000000d8b00b82>] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: (&ldata->atomic_read_lock){+.+.}, at: [<00000000159f44d6>] n_tty_read+0x2f2/0x1a10 drivers/tty/n_tty.c:2131 2 locks held by getty/3123: #0: (&tty->ldisc_sem){++++}, at: [<00000000d8b00b82>] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: (&ldata->atomic_read_lock){+.+.}, at: [<00000000159f44d6>] n_tty_read+0x2f2/0x1a10 drivers/tty/n_tty.c:2131 2 locks held by getty/3124: #0: (&tty->ldisc_sem){++++}, at: [<00000000d8b00b82>] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: (&ldata->atomic_read_lock){+.+.}, at: [<00000000159f44d6>] n_tty_read+0x2f2/0x1a10 drivers/tty/n_tty.c:2131 2 locks held by getty/3125: #0: (&tty->ldisc_sem){++++}, at: [<00000000d8b00b82>] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: (&ldata->atomic_read_lock){+.+.}, at: [<00000000159f44d6>] n_tty_read+0x2f2/0x1a10 drivers/tty/n_tty.c:2131 3 locks held by kworker/u4:9/6381: #0: ((wq_completion)"writeback"){+.+.}, at: [<00000000a81ae46f>] __write_once_size include/linux/compiler.h:212 [inline] #0: ((wq_completion)"writeback"){+.+.}, at: [<00000000a81ae46f>] atomic64_set arch/x86/include/asm/atomic64_64.h:34 [inline] #0: ((wq_completion)"writeback"){+.+.}, at: [<00000000a81ae46f>] atomic_long_set include/asm-generic/atomic-long.h:57 [inline] #0: ((wq_completion)"writeback"){+.+.}, at: [<00000000a81ae46f>] set_work_data kernel/workqueue.c:618 [inline] #0: ((wq_completion)"writeback"){+.+.}, at: [<00000000a81ae46f>] set_work_pool_and_clear_pending kernel/workqueue.c:645 [inline] #0: ((wq_completion)"writeback"){+.+.}, at: [<00000000a81ae46f>] process_one_work+0xad4/0x1be0 kernel/workqueue.c:2083 #1: ((work_completion)(&(&wb->dwork)->work)){+.+.}, at: [<00000000bdf66090>] process_one_work+0xb2f/0x1be0 kernel/workqueue.c:2087 #2: (&type->s_umount_key#25){.+.+}, at: [<00000000418890df>] trylock_super+0x20/0x100 fs/super.c:396 1 lock held by syz-executor2/14179: #0: (&mm->mmap_sem){++++}, at: [<0000000040d4f444>] exit_mm kernel/exit.c:510 [inline] #0: (&mm->mmap_sem){++++}, at: [<0000000040d4f444>] do_exit+0x4b0/0x1ae0 kernel/exit.c:852 1 lock held by syz-executor2/14182: #0: (&mm->mmap_sem){++++}, at: [<0000000040d4f444>] exit_mm kernel/exit.c:510 [inline] #0: (&mm->mmap_sem){++++}, at: [<0000000040d4f444>] do_exit+0x4b0/0x1ae0 kernel/exit.c:852 1 lock held by syz-executor2/14191: #0: (&mm->mmap_sem){++++}, at: [<0000000060bd7885>] vm_mmap_pgoff+0x198/0x280 mm/util.c:331 1 lock held by syz-executor2/14200: #0: (&mm->mmap_sem){++++}, at: [<00000000b28d5284>] __do_page_fault+0x84b/0xc90 arch/x86/mm/fault.c:1365 1 lock held by syz-executor6/14193: #0: (&bdev->bd_mutex){+.+.}, at: [<00000000405eaae6>] iterate_bdevs+0xc8/0x260 fs/block_dev.c:2145 1 lock held by syz-executor6/14201: #0: (&bdev->bd_mutex){+.+.}, at: [<00000000405eaae6>] iterate_bdevs+0xc8/0x260 fs/block_dev.c:2145 2 locks held by getty/14303: #0: (&tty->ldisc_sem){++++}, at: [<00000000d8b00b82>] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: (&ldata->atomic_read_lock){+.+.}, at: [<00000000159f44d6>] n_tty_read+0x2f2/0x1a10 drivers/tty/n_tty.c:2131 ============================================= NMI backtrace for cpu 0 CPU: 0 PID: 674 Comm: khungtaskd Not tainted 4.15.0-rc3+ #132 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+0x37a/0x440 kernel/kthread.c:238 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:441 Sending NMI from CPU 0 to CPUs 1: NMI backtrace for cpu 1 skipped: idling at native_safe_halt+0x6/0x10 arch/x86/include/asm/irqflags.h:54