syzbot

sd 0:0:1:0: [sg0] tag#195 CDB[10]: 37 d1 65 58 f4 3c 3d 6f e1 ea b2 df 07 eb 4f 9b
sd 0:0:1:0: [sg0] tag#195 CDB[20]: 33
INFO: task syz-executor4:17156 blocked for more than 120 seconds.
      Not tainted 4.9.109-ga4230be #51
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor4   D25384 17156   3834 0x00000004
 ffff8801d6826000 0000000000000000 ffff8801d07a5a40 ffff880198858000
 ffff8801db221c18 ffff880190c3f890 ffffffff839e8a8d 1ffff10032187f06
 ffffffff855802b0 0000000041b58ab3 00ffffff843c2288 ffff8801db2224e8
Call Trace:
 [<ffffffff839ea08f>] schedule+0x7f/0x1b0 kernel/sched/core.c:3557
 [<ffffffff839f64a1>] schedule_timeout+0x861/0xf70 kernel/time/timer.c:1768
 [<ffffffff839e826a>] io_schedule_timeout+0x1ba/0x390 kernel/sched/core.c:5180
 [<ffffffff839eb4d9>] io_schedule include/linux/sched.h:460 [inline]
 [<ffffffff839eb4d9>] bit_wait_io+0x19/0xa0 kernel/sched/wait.c:582
 [<ffffffff839ead7e>] __wait_on_bit_lock+0xce/0x1c0 kernel/sched/wait.c:421
 [<ffffffff8143451f>] __lock_page+0xff/0x160 mm/filemap.c:934
 [<ffffffff8143a2e9>] lock_page include/linux/pagemap.h:454 [inline]
 [<ffffffff8143a2e9>] pagecache_get_page+0x409/0x720 mm/filemap.c:1216
 [<ffffffff8146bbe6>] find_lock_page include/linux/pagemap.h:284 [inline]
 [<ffffffff8146bbe6>] truncate_inode_pages_range+0xca6/0x1290 mm/truncate.c:320
 [<ffffffff8163288d>] blkdev_fallocate+0x21d/0x440 fs/block_dev.c:1817
 [<ffffffff815686b9>] vfs_fallocate+0x359/0x600 fs/open.c:329
 [<ffffffff8156b5c3>] SYSC_fallocate fs/open.c:352 [inline]
 [<ffffffff8156b5c3>] SyS_fallocate+0x53/0x90 fs/open.c:346
 [<ffffffff81006316>] do_syscall_64+0x1a6/0x490 arch/x86/entry/common.c:282
 [<ffffffff839f9993>] entry_SYSCALL_64_after_swapgs+0x5d/0xdb

Showing all locks held in the system:
2 locks held by khungtaskd/519:
 #0:  (rcu_read_lock){......}, at: [<ffffffff8136662c>] check_hung_uninterruptible_tasks kernel/hung_task.c:168 [inline]
 #0:  (rcu_read_lock){......}, at: [<ffffffff8136662c>] watchdog+0x11c/0xa20 kernel/hung_task.c:239
 #1:  (tasklist_lock){.+.+..}, at: [<ffffffff81425cb7>] debug_show_all_locks+0x79/0x218 kernel/locking/lockdep.c:4336
1 lock held by rsyslogd/3680:
 #0:  (&f->f_pos_lock){+.+.+.}, at: [<ffffffff815d803c>] __fdget_pos+0xac/0xd0 fs/file.c:781
2 locks held by getty/3776:
 #0:  (&tty->ldisc_sem){++++++}, at: [<ffffffff839f7b32>] ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:367
 #1:  (&ldata->atomic_read_lock){+.+...}, at: [<ffffffff8211fce2>] n_tty_read+0x202/0x16e0 drivers/tty/n_tty.c:2133
1 lock held by syz-executor4/17156:
 #0:  (sb_writers){.+.+.+}, at: [<ffffffff8156865b>] sb_start_write include/linux/fs.h:1573 [inline]
 #0:  (sb_writers){.+.+.+}, at: [<ffffffff8156865b>] vfs_fallocate+0x2fb/0x600 fs/open.c:328
1 lock held by syz-executor4/17204:
 #0:  (sb_writers){.+.+.+}, at: [<ffffffff8156865b>] sb_start_write include/linux/fs.h:1573 [inline]
 #0:  (sb_writers){.+.+.+}, at: [<ffffffff8156865b>] vfs_fallocate+0x2fb/0x600 fs/open.c:328

=============================================

NMI backtrace for cpu 1
CPU: 1 PID: 519 Comm: khungtaskd Not tainted 4.9.109-ga4230be #51
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
 ffff8801d85cfd08 ffffffff81eb3e29 0000000000000000 0000000000000001
 0000000000000001 0000000000000001 ffffffff810b9580 ffff8801d85cfd40
 ffffffff81ebf127 0000000000000001 0000000000000000 0000000000000003
Call Trace:
 [<ffffffff81eb3e29>] __dump_stack lib/dump_stack.c:15 [inline]
 [<ffffffff81eb3e29>] dump_stack+0xc1/0x128 lib/dump_stack.c:51
 [<ffffffff81ebf127>] nmi_cpu_backtrace.cold.2+0x48/0x87 lib/nmi_backtrace.c:99
 [<ffffffff81ebf0ba>] nmi_trigger_cpumask_backtrace+0x12a/0x14f lib/nmi_backtrace.c:60
 [<ffffffff810b9684>] arch_trigger_cpumask_backtrace+0x14/0x20 arch/x86/kernel/apic/hw_nmi.c:37
 [<ffffffff81366bc4>] trigger_all_cpu_backtrace include/linux/nmi.h:58 [inline]
 [<ffffffff81366bc4>] check_hung_task kernel/hung_task.c:125 [inline]
 [<ffffffff81366bc4>] check_hung_uninterruptible_tasks kernel/hung_task.c:182 [inline]
 [<ffffffff81366bc4>] watchdog+0x6b4/0xa20 kernel/hung_task.c:239
 [<ffffffff8119d04d>] kthread+0x26d/0x300 kernel/kthread.c:211
 [<ffffffff839f9b5c>] ret_from_fork+0x5c/0x70 arch/x86/entry/entry_64.S:373
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0 skipped: idling at pc 0xffffffff839f8596