INFO: task syz-executor1:7278 blocked for more than 120 seconds. Not tainted 4.17.0-rc3+ #33 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor1 D22272 7278 1 0x00000004 Call Trace: context_switch kernel/sched/core.c:2848 [inline] __schedule+0x801/0x1e30 kernel/sched/core.c:3490 schedule+0xef/0x430 kernel/sched/core.c:3549 wb_wait_for_completion+0x1ed/0x2d0 fs/fs-writeback.c:221 __writeback_inodes_sb_nr+0x3e8/0x550 fs/fs-writeback.c:2340 writeback_inodes_sb_nr fs/fs-writeback.c:2357 [inline] writeback_inodes_sb+0x27/0x30 fs/fs-writeback.c:2372 __sync_filesystem fs/sync.c:36 [inline] sync_filesystem+0x15f/0x310 fs/sync.c:64 generic_shutdown_super+0xd7/0x520 fs/super.c:429 kill_block_super+0xa4/0x100 fs/super.c:1191 deactivate_locked_super+0x97/0x100 fs/super.c:316 deactivate_super+0x188/0x1b0 fs/super.c:347 cleanup_mnt+0xbf/0x160 fs/namespace.c:1174 __cleanup_mnt+0x16/0x20 fs/namespace.c:1181 task_work_run+0x1e4/0x290 kernel/task_work.c:113 tracehook_notify_resume include/linux/tracehook.h:191 [inline] exit_to_usermode_loop+0x2bd/0x310 arch/x86/entry/common.c:166 prepare_exit_to_usermode arch/x86/entry/common.c:196 [inline] syscall_return_slowpath arch/x86/entry/common.c:265 [inline] do_syscall_64+0x6ac/0x800 arch/x86/entry/common.c:290 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x458387 RSP: 002b:00007ffc051d1a68 EFLAGS: 00000246 ORIG_RAX: 00000000000000a6 RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000458387 RDX: 00000000019449bb RSI: 0000000000000002 RDI: 00007ffc051d2bd0 RBP: 00007ffc051d2bd0 R08: 0000000000000000 R09: 0000000000000009 R10: 0000000000000005 R11: 0000000000000246 R12: 0000000001944940 R13: 0000000000000000 R14: 0000000000000109 R15: 0000000000017932 Showing all locks held in the system: 2 locks held by khungtaskd/892: #0: 000000001ac31c24 (rcu_read_lock){....}, at: check_hung_uninterruptible_tasks kernel/hung_task.c:175 [inline] #0: 000000001ac31c24 (rcu_read_lock){....}, at: watchdog+0x1ff/0xf60 kernel/hung_task.c:249 #1: 0000000045e06767 (tasklist_lock){.+.+}, at: debug_show_all_locks+0xde/0x34a kernel/locking/lockdep.c:4470 2 locks held by getty/4300: #0: 000000003ca1b2b0 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: 0000000010d54e16 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x321/0x1cc0 drivers/tty/n_tty.c:2131 2 locks held by getty/4301: #0: 00000000d4e4ebac (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: 000000006929ae0e (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x321/0x1cc0 drivers/tty/n_tty.c:2131 2 locks held by getty/4302: #0: 0000000078b6a850 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: 00000000ab83c7ac (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x321/0x1cc0 drivers/tty/n_tty.c:2131 2 locks held by getty/4303: #0: 00000000bda520ca (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: 000000001a2ad34c (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x321/0x1cc0 drivers/tty/n_tty.c:2131 2 locks held by getty/4304: #0: 00000000252f329c (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: 0000000005b7e818 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x321/0x1cc0 drivers/tty/n_tty.c:2131 2 locks held by getty/4305: #0: 00000000475c67e1 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: 0000000096b41703 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x321/0x1cc0 drivers/tty/n_tty.c:2131 2 locks held by getty/4306: #0: 0000000030874ebc (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: 00000000168a6d35 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x321/0x1cc0 drivers/tty/n_tty.c:2131 1 lock held by syz-executor1/7278: #0: 00000000a777ee78 (&type->s_umount_key#44){+.+.}, at: deactivate_super+0x180/0x1b0 fs/super.c:346 ============================================= NMI backtrace for cpu 1 CPU: 1 PID: 892 Comm: khungtaskd Not tainted 4.17.0-rc3+ #33 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+0x1b9/0x294 lib/dump_stack.c:113 nmi_cpu_backtrace.cold.4+0x19/0xce lib/nmi_backtrace.c:103 nmi_trigger_cpumask_backtrace+0x151/0x192 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+0xc10/0xf60 kernel/hung_task.c:249 kthread+0x345/0x410 kernel/kthread.c:238 ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:412 Sending NMI from CPU 1 to CPUs 0: NMI backtrace for cpu 0 CPU: 0 PID: 22 Comm: kworker/u4:1 Not tainted 4.17.0-rc3+ #33 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Workqueue: writeback wb_workfn (flush-7:1) RIP: 0010:bytes_is_nonzero mm/kasan/kasan.c:166 [inline] RIP: 0010:memory_is_nonzero mm/kasan/kasan.c:184 [inline] RIP: 0010:memory_is_poisoned_n mm/kasan/kasan.c:210 [inline] RIP: 0010:memory_is_poisoned mm/kasan/kasan.c:241 [inline] RIP: 0010:check_memory_region_inline mm/kasan/kasan.c:257 [inline] RIP: 0010:check_memory_region+0x103/0x1b0 mm/kasan/kasan.c:267 RSP: 0018:ffff8801d941dfe0 EFLAGS: 00000202 RAX: ffffed003b5c46c2 RBX: 1ffff1003b5c46c2 RCX: ffffffff81643fe5 RDX: 0000000000000000 RSI: 0000000000000004 RDI: ffff8801dae23610 RBP: ffff8801d941dff8 R08: 0000000000000001 R09: ffffed003b5c46c2 R10: ffffed003b5c46c2 R11: ffff8801dae23613 R12: ffffed003b5c46c3 R13: ffff8801dae23610 R14: ffff8801d941e080 R15: dffffc0000000000 FS: 0000000000000000(0000) GS:ffff8801dae00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: ffffffffff600400 CR3: 00000001cf204000 CR4: 00000000001406f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: kasan_check_read+0x11/0x20 mm/kasan/kasan.c:272 atomic_read include/asm-generic/atomic-instrumented.h:21 [inline] rcu_dynticks_curr_cpu_in_eqs kernel/rcu/tree.c:349 [inline] rcu_is_watching+0x85/0x140 kernel/rcu/tree.c:1075 rcu_read_lock include/linux/rcupdate.h:633 [inline] find_get_entry+0x88b/0xb90 mm/filemap.c:1428 pagecache_get_page+0x116/0xe20 mm/filemap.c:1541 find_or_create_page include/linux/pagemap.h:322 [inline] grow_dev_page fs/buffer.c:940 [inline] grow_buffers fs/buffer.c:1009 [inline] __getblk_slow fs/buffer.c:1036 [inline] __getblk_gfp+0x39e/0xaf0 fs/buffer.c:1313 __bread_gfp+0x2d/0x310 fs/buffer.c:1347 sb_bread include/linux/buffer_head.h:309 [inline] fat_clusters_flush+0x127/0x3c0 fs/fat/misc.c:69 fat_write_inode+0x110/0x180 fs/fat/inode.c:891 write_inode fs/fs-writeback.c:1183 [inline] __writeback_single_inode+0xf18/0x15c0 fs/fs-writeback.c:1382 writeback_sb_inodes+0x6f0/0x11a0 fs/fs-writeback.c:1587 wb_writeback+0x463/0xf50 fs/fs-writeback.c:1763 wb_do_writeback fs/fs-writeback.c:1908 [inline] wb_workfn+0x46f/0x1770 fs/fs-writeback.c:1949 process_one_work+0xc1e/0x1b50 kernel/workqueue.c:2145 worker_thread+0x1cc/0x1440 kernel/workqueue.c:2279 kthread+0x345/0x410 kernel/kthread.c:238 ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:412 Code: 83 c0 01 48 89 d8 49 39 d8 74 10 41 80 38 00 74 ee 4b 8d 44 0d 00 4d 85 c0 75 3e 4d 89 e0 49 29 c0 e9 6c ff ff ff 4d 85 c0 74 ba <48> b8 01 00 00 00 00 fc ff df 4d 01 c8 48 01 d8 41 80 39 00 74 INFO: NMI handler (nmi_cpu_backtrace_handler) took too long to run: 1.436 msecs