INFO: task syz-executor0:9009 blocked for more than 140 seconds. Not tainted 4.20.0-rc2+ #333 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor0 D21528 9009 6079 0x80000002 Call Trace: context_switch kernel/sched/core.c:2831 [inline] __schedule+0x8cf/0x21d0 kernel/sched/core.c:3472 schedule+0xfe/0x460 kernel/sched/core.c:3516 wb_wait_for_completion+0x1f9/0x2d0 fs/fs-writeback.c:221 __writeback_inodes_sb_nr+0x405/0x580 fs/fs-writeback.c:2333 writeback_inodes_sb_nr fs/fs-writeback.c:2350 [inline] writeback_inodes_sb+0x27/0x30 fs/fs-writeback.c:2365 __sync_filesystem fs/sync.c:36 [inline] sync_filesystem+0x16f/0x330 fs/sync.c:64 generic_shutdown_super+0xdd/0x530 fs/super.c:442 kill_block_super+0x9e/0x100 fs/super.c:1185 deactivate_locked_super+0x97/0x100 fs/super.c:329 deactivate_super+0x2bb/0x320 fs/super.c:360 cleanup_mnt+0xbf/0x160 fs/namespace.c:1098 __cleanup_mnt+0x16/0x20 fs/namespace.c:1105 task_work_run+0x1e8/0x2a0 kernel/task_work.c:113 exit_task_work include/linux/task_work.h:22 [inline] do_exit+0x1ad6/0x26d0 kernel/exit.c:867 do_group_exit+0x177/0x440 kernel/exit.c:970 get_signal+0x8b0/0x1980 kernel/signal.c:2517 do_signal+0x9c/0x21c0 arch/x86/kernel/signal.c:816 exit_to_usermode_loop+0x2e5/0x380 arch/x86/entry/common.c:162 prepare_exit_to_usermode arch/x86/entry/common.c:197 [inline] syscall_return_slowpath arch/x86/entry/common.c:268 [inline] do_syscall_64+0x6be/0x820 arch/x86/entry/common.c:293 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x457569 Code: fd b3 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 0f 83 cb b3 fb ff c3 66 2e 0f 1f 84 00 00 00 00 RSP: 002b:00007f7cf6c09cf8 EFLAGS: 00000246 ORIG_RAX: 00000000000000ca RAX: fffffffffffffe00 RBX: 000000000072bfa8 RCX: 0000000000457569 RDX: 0000000000000000 RSI: 0000000000000080 RDI: 000000000072bfa8 RBP: 000000000072bfa0 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 000000000072bfac R13: 00007ffeac4c77af R14: 00007f7cf6c0a9c0 R15: 0000000000000001 Showing all locks held in the system: 3 locks held by kworker/u4:1/21: 1 lock held by khungtaskd/1007: #0: 000000002bc23063 (rcu_read_lock){....}, at: debug_show_all_locks+0xd0/0x424 kernel/locking/lockdep.c:4379 1 lock held by rsyslogd/5948: #0: 000000007236a98d (&f->f_pos_lock){+.+.}, at: __fdget_pos+0x1bb/0x200 fs/file.c:766 2 locks held by getty/6038: #0: 000000002878d27a (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:353 #1: 00000000290f6e8f (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x335/0x1e80 drivers/tty/n_tty.c:2154 2 locks held by getty/6039: #0: 000000009bf1c2d1 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:353 #1: 00000000c27da22b (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x335/0x1e80 drivers/tty/n_tty.c:2154 2 locks held by getty/6040: #0: 000000008c307f16 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:353 #1: 0000000054db0685 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x335/0x1e80 drivers/tty/n_tty.c:2154 2 locks held by getty/6041: #0: 000000007a1bbeb0 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:353 #1: 000000000a996c0c (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x335/0x1e80 drivers/tty/n_tty.c:2154 2 locks held by getty/6042: #0: 00000000cfb125fd (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:353 #1: 000000000747a4ff (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x335/0x1e80 drivers/tty/n_tty.c:2154 2 locks held by getty/6043: #0: 0000000024bf2a4e (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:353 #1: 00000000d6cc8b05 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x335/0x1e80 drivers/tty/n_tty.c:2154 2 locks held by getty/6044: #0: 000000009da357ee (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:353 #1: 0000000012ad632b (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x335/0x1e80 drivers/tty/n_tty.c:2154 1 lock held by syz-executor0/9009: #0: 00000000c684abfa (&type->s_umount_key#51){++++}, at: deactivate_super+0x2b3/0x320 fs/super.c:359 1 lock held by syz-executor0/9851: #0: 0000000096b30812 (&sig->cred_guard_mutex){+.+.}, at: prepare_bprm_creds+0x53/0x120 fs/exec.c:1404 ============================================= NMI backtrace for cpu 0 CPU: 0 PID: 1007 Comm: khungtaskd Not tainted 4.20.0-rc2+ #333 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0x244/0x39d lib/dump_stack.c:113 nmi_cpu_backtrace.cold.2+0x5c/0xa1 lib/nmi_backtrace.c:101 nmi_trigger_cpumask_backtrace+0x1e8/0x22a 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:146 [inline] check_hung_uninterruptible_tasks kernel/hung_task.c:205 [inline] watchdog+0xb51/0x1060 kernel/hung_task.c:289 kthread+0x35a/0x440 kernel/kthread.c:246 ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:352 Sending NMI from CPU 0 to CPUs 1: INFO: NMI handler (nmi_cpu_backtrace_handler) took too long to run: 2.403 msecs NMI backtrace for cpu 1 CPU: 1 PID: 21 Comm: kworker/u4:1 Not tainted 4.20.0-rc2+ #333 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Workqueue: writeback wb_workfn (flush-7:0) RIP: 0010:check_memory_region+0xc3/0x1b0 mm/kasan/kasan.c:268 Code: 84 a8 00 00 00 48 83 38 00 74 ed 4c 8d 40 08 eb 09 48 83 c0 01 49 39 c0 74 0a 80 38 00 74 f2 48 85 c0 75 77 5b 41 5c 41 5d 5d 41 bd 08 00 00 00 4d 89 c8 41 29 dd 4b 8d 5c 0d 00 eb 0c 49 83 RSP: 0018:ffff8881d944da28 EFLAGS: 00000246 RAX: ffffed103b5e5b68 RBX: 1ffff1103b289b49 RCX: ffffffff816a6e82 RDX: 0000000000000000 RSI: 0000000000000004 RDI: ffff8881daf2db38 RBP: ffff8881d944da30 R08: ffffed103b5e5b68 R09: ffffed103b5e5b67 R10: ffffed103b5e5b67 R11: ffff8881daf2db3b R12: ffff8881daf2da80 R13: ffff8881d944daa8 R14: ffff8881daf2db38 R15: ffff8881d944dbb8 FS: 0000000000000000(0000) GS:ffff8881daf00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f3a72d81fc0 CR3: 00000001b6c58000 CR4: 00000000001426e0 Call Trace: atomic_read include/asm-generic/atomic-instrumented.h:21 [inline] rcu_dynticks_curr_cpu_in_eqs+0xa2/0x170 kernel/rcu/tree.c:292 rcu_is_watching+0x10/0x30 kernel/rcu/tree.c:906 rcu_read_lock_held+0x87/0xc0 kernel/rcu/update.c:277 xa_entry include/linux/xarray.h:709 [inline] xas_descend+0x413/0x510 lib/xarray.c:198 xas_load+0x145/0x1e0 lib/xarray.c:234 find_get_entry+0x3ca/0x1120 mm/filemap.c:1415 pagecache_get_page+0x12f/0xf00 mm/filemap.c:1518 find_get_page_flags include/linux/pagemap.h:278 [inline] __find_get_block_slow fs/buffer.c:205 [inline] __find_get_block+0x63a/0xf20 fs/buffer.c:1294 __getblk_slow fs/buffer.c:1039 [inline] __getblk_gfp+0x2b3/0xd50 fs/buffer.c:1320 __bread_gfp+0x2d/0x310 fs/buffer.c:1354 sb_bread include/linux/buffer_head.h:307 [inline] __fat_write_inode+0x347/0xb60 fs/fat/inode.c:859 fat_write_inode+0x97/0x180 fs/fat/inode.c:908 write_inode fs/fs-writeback.c:1176 [inline] __writeback_single_inode+0xf56/0x1660 fs/fs-writeback.c:1375 writeback_sb_inodes+0x71f/0x1210 fs/fs-writeback.c:1580 wb_writeback+0x48c/0xfc0 fs/fs-writeback.c:1756 wb_do_writeback fs/fs-writeback.c:1901 [inline] wb_workfn+0x495/0x1790 fs/fs-writeback.c:1942 process_one_work+0xc90/0x1c40 kernel/workqueue.c:2153 worker_thread+0x17f/0x1390 kernel/workqueue.c:2296 kthread+0x35a/0x440 kernel/kthread.c:246 ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:352