Message-ID: <0000000000002cd22305879b22c4@google.com>
Date:   Sun, 28 Apr 2019 11:14:06 -0700
From:   syzbot <syzbot+10007d66ca02b08f0e60@...kaller.appspotmail.com>
To:     axboe@...nel.dk, dvyukov@...gle.com, jack@...e.cz,
        linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org,
        penguin-kernel@...ove.SAKURA.ne.jp,
        penguin-kernel@...ove.sakura.ne.jp,
        syzkaller-bugs@...glegroups.com, viro@...iv.linux.org.uk
Subject: Re: INFO: task hung in __get_super

syzbot has found a reproducer for the following crash on:

HEAD commit:    037904a2 Merge branch 'x86-urgent-for-linus' of git://git...
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=135ff034a00000
kernel config:  https://syzkaller.appspot.com/x/.config?x=a42d110b47dd6b36
dashboard link: https://syzkaller.appspot.com/bug?extid=10007d66ca02b08f0e60
compiler:       gcc (GCC) 9.0.0 20181231 (experimental)
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=1291b1f4a00000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=135385a8a00000

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+10007d66ca02b08f0e60@...kaller.appspotmail.com

INFO: task syz-executor274:8097 blocked for more than 143 seconds.
       Not tainted 5.1.0-rc6+ #89
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor274 D28008  8097   8041 0x00000004
Call Trace:
  context_switch kernel/sched/core.c:2877 [inline]
  __schedule+0x813/0x1cc0 kernel/sched/core.c:3518
  schedule+0x92/0x180 kernel/sched/core.c:3562
  __rwsem_down_read_failed_common kernel/locking/rwsem-xadd.c:285 [inline]
  rwsem_down_read_failed+0x213/0x420 kernel/locking/rwsem-xadd.c:302
  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+0x49/0x90 kernel/locking/rwsem.c:26
  __get_super.part.0+0x203/0x2e0 fs/super.c:788
  __get_super include/linux/spinlock.h:329 [inline]
  get_super+0x2e/0x50 fs/super.c:817
  fsync_bdev+0x19/0xd0 fs/block_dev.c:525
  invalidate_partition+0x36/0x60 block/genhd.c:1581
  drop_partitions block/partition-generic.c:443 [inline]
  rescan_partitions+0xef/0xa20 block/partition-generic.c:516
  __blkdev_reread_part+0x1a2/0x230 block/ioctl.c:173
  blkdev_reread_part+0x27/0x40 block/ioctl.c:193
  loop_reread_partitions+0x1c/0x40 drivers/block/loop.c:633
  loop_set_status+0xe57/0x1380 drivers/block/loop.c:1296
  loop_set_status64+0xc2/0x120 drivers/block/loop.c:1416
  lo_ioctl+0x8fc/0x2150 drivers/block/loop.c:1559
  __blkdev_driver_ioctl block/ioctl.c:303 [inline]
  blkdev_ioctl+0x6f2/0x1d10 block/ioctl.c:605
  block_ioctl+0xee/0x130 fs/block_dev.c:1933
  vfs_ioctl fs/ioctl.c:46 [inline]
  file_ioctl fs/ioctl.c:509 [inline]
  do_vfs_ioctl+0xd6e/0x1390 fs/ioctl.c:696
  ksys_ioctl+0xab/0xd0 fs/ioctl.c:713
  __do_sys_ioctl fs/ioctl.c:720 [inline]
  __se_sys_ioctl fs/ioctl.c:718 [inline]
  __x64_sys_ioctl+0x73/0xb0 fs/ioctl.c:718
  do_syscall_64+0x103/0x610 arch/x86/entry/common.c:290
  entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x441937
Code: 48 83 c4 08 48 89 d8 5b 5d c3 66 0f 1f 84 00 00 00 00 00 48 89 e8 48  
f7 d8 48 39 c3 0f 92 c0 eb 92 66 90 b8 10 00 00 00 0f 05 <48> 3d 01 f0 ff  
ff 0f 83 8d 08 fc ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007ffcabed4e08 EFLAGS: 00000202 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 0000000000441937
RDX: 00007ffcabed4ea0 RSI: 0000000000004c04 RDI: 0000000000000004
RBP: 0000000000000003 R08: 0000000000000000 R09: 000000000000000a
R10: 0000000000000075 R11: 0000000000000202 R12: 0000000000000001
R13: 0000000000000004 R14: 0000000000000000 R15: 0000000000000000
INFO: task blkid:8099 blocked for more than 143 seconds.
       Not tainted 5.1.0-rc6+ #89
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
blkid           D27504  8099   8021 0x00000004
Call Trace:
  context_switch kernel/sched/core.c:2877 [inline]
  __schedule+0x813/0x1cc0 kernel/sched/core.c:3518
  schedule+0x92/0x180 kernel/sched/core.c:3562
  schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:3620
  __mutex_lock_common kernel/locking/mutex.c:1002 [inline]
  __mutex_lock+0x726/0x1310 kernel/locking/mutex.c:1072
  mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:1087
  blkdev_put+0x34/0x560 fs/block_dev.c:1866
  blkdev_close+0x8b/0xb0 fs/block_dev.c:1915
  __fput+0x2e5/0x8d0 fs/file_table.c:278
  ____fput+0x16/0x20 fs/file_table.c:309
  task_work_run+0x14a/0x1c0 kernel/task_work.c:113
  tracehook_notify_resume include/linux/tracehook.h:188 [inline]
  exit_to_usermode_loop+0x273/0x2c0 arch/x86/entry/common.c:166
  prepare_exit_to_usermode arch/x86/entry/common.c:197 [inline]
  syscall_return_slowpath arch/x86/entry/common.c:268 [inline]
  do_syscall_64+0x52d/0x610 arch/x86/entry/common.c:293
  entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x7f1ae9c432b0
Code: Bad RIP value.
RSP: 002b:00007ffc29ff6028 EFLAGS: 00000246 ORIG_RAX: 0000000000000003
RAX: 0000000000000000 RBX: 0000000000000000 RCX: 00007f1ae9c432b0
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000003
RBP: 0000000000000000 R08: 0000000000000028 R09: 0000000001680000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000b9d030
R13: 0000000000000000 R14: 0000000000000003 R15: 0000000000000005

Showing all locks held in the system:
1 lock held by khungtaskd/1041:
  #0: 0000000027887009 (rcu_read_lock){....}, at:  
debug_show_all_locks+0x5f/0x27e kernel/locking/lockdep.c:5057
1 lock held by rs:main Q:Reg/7921:
  #0: 00000000e00580d7 (&rq->lock){-.-.}, at: rq_lock  
kernel/sched/sched.h:1168 [inline]
  #0: 00000000e00580d7 (&rq->lock){-.-.}, at: __schedule+0x1f8/0x1cc0  
kernel/sched/core.c:3456
1 lock held by rsyslogd/7923:
  #0: 00000000488dcec4 (&f->f_pos_lock){+.+.}, at: __fdget_pos+0xee/0x110  
fs/file.c:801
2 locks held by getty/8014:
  #0: 000000001b56f3c3 (&tty->ldisc_sem){++++}, at:  
ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:341
  #1: 00000000da9faa8c (&ldata->atomic_read_lock){+.+.}, at:  
n_tty_read+0x232/0x1b70 drivers/tty/n_tty.c:2156
2 locks held by getty/8015:
  #0: 00000000e00c81bb (&tty->ldisc_sem){++++}, at:  
ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:341
  #1: 000000008d689a2e (&ldata->atomic_read_lock){+.+.}, at:  
n_tty_read+0x232/0x1b70 drivers/tty/n_tty.c:2156
2 locks held by getty/8016:
  #0: 00000000177f6359 (&tty->ldisc_sem){++++}, at:  
ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:341
  #1: 0000000096437898 (&ldata->atomic_read_lock){+.+.}, at:  
n_tty_read+0x232/0x1b70 drivers/tty/n_tty.c:2156
2 locks held by getty/8017:
  #0: 000000002db00e12 (&tty->ldisc_sem){++++}, at:  
ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:341
  #1: 0000000071f2d88e (&ldata->atomic_read_lock){+.+.}, at:  
n_tty_read+0x232/0x1b70 drivers/tty/n_tty.c:2156
2 locks held by getty/8018:
  #0: 00000000a41b6290 (&tty->ldisc_sem){++++}, at:  
ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:341
  #1: 00000000c340e26f (&ldata->atomic_read_lock){+.+.}, at:  
n_tty_read+0x232/0x1b70 drivers/tty/n_tty.c:2156
2 locks held by getty/8019:
  #0: 00000000bca104ce (&tty->ldisc_sem){++++}, at:  
ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:341
  #1: 000000007e045212 (&ldata->atomic_read_lock){+.+.}, at:  
n_tty_read+0x232/0x1b70 drivers/tty/n_tty.c:2156
2 locks held by getty/8020:
  #0: 0000000070fdafae (&tty->ldisc_sem){++++}, at:  
ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:341
  #1: 00000000b4e26fa9 (&ldata->atomic_read_lock){+.+.}, at:  
n_tty_read+0x232/0x1b70 drivers/tty/n_tty.c:2156
1 lock held by syz-executor274/8083:
2 locks held by syz-executor274/8097:
  #0: 000000007a5ed526 (&bdev->bd_mutex){+.+.}, at:  
blkdev_reread_part+0x1f/0x40 block/ioctl.c:192
  #1: 0000000067606e21 (&type->s_umount_key#39){.+.+}, at:  
__get_super.part.0+0x203/0x2e0 fs/super.c:788
1 lock held by blkid/8099:
  #0: 000000007a5ed526 (&bdev->bd_mutex){+.+.}, at: blkdev_put+0x34/0x560  
fs/block_dev.c:1866
2 locks held by syz-executor274/11705:
  #0: 000000002b6bbb34 (&bdev->bd_mutex){+.+.}, at: __blkdev_put+0xbb/0x810  
fs/block_dev.c:1833
  #1: 00000000bde6230e (loop_ctl_mutex){+.+.}, at: lo_release+0x1f/0x200  
drivers/block/loop.c:1755
2 locks held by syz-executor274/11709:
  #0: 00000000a45cb906 (&bdev->bd_mutex){+.+.}, at: __blkdev_put+0xbb/0x810  
fs/block_dev.c:1833
  #1: 00000000bde6230e (loop_ctl_mutex){+.+.}, at: lo_release+0x1f/0x200  
drivers/block/loop.c:1755
2 locks held by syz-executor274/11716:
  #0: 00000000a19e2025 (&type->s_umount_key#38/1){+.+.}, at:  
alloc_super+0x158/0x890 fs/super.c:228
  #1: 00000000bde6230e (loop_ctl_mutex){+.+.}, at: lo_simple_ioctl  
drivers/block/loop.c:1514 [inline]
  #1: 00000000bde6230e (loop_ctl_mutex){+.+.}, at: lo_ioctl+0x266/0x2150  
drivers/block/loop.c:1572
2 locks held by syz-executor274/11717:
  #0: 00000000e185c083 (&type->s_umount_key#38/1){+.+.}, at:  
alloc_super+0x158/0x890 fs/super.c:228
  #1: 00000000bde6230e (loop_ctl_mutex){+.+.}, at: lo_simple_ioctl  
drivers/block/loop.c:1514 [inline]
  #1: 00000000bde6230e (loop_ctl_mutex){+.+.}, at: lo_ioctl+0x266/0x2150  
drivers/block/loop.c:1572
2 locks held by blkid/11718:
  #0: 000000003d9e77b2 (&bdev->bd_mutex){+.+.}, at: __blkdev_put+0xbb/0x810  
fs/block_dev.c:1833
  #1: 00000000bde6230e (loop_ctl_mutex){+.+.}, at: __loop_clr_fd+0x88/0xd60  
drivers/block/loop.c:1046
2 locks held by blkid/11720:
  #0: 000000000c0297bc (&bdev->bd_mutex){+.+.}, at: __blkdev_put+0xbb/0x810  
fs/block_dev.c:1833
  #1: 00000000bde6230e (loop_ctl_mutex){+.+.}, at: lo_release+0x1f/0x200  
drivers/block/loop.c:1755

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

NMI backtrace for cpu 0
CPU: 0 PID: 1041 Comm: khungtaskd Not tainted 5.1.0-rc6+ #89
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+0x172/0x1f0 lib/dump_stack.c:113
  nmi_cpu_backtrace.cold+0x63/0xa4 lib/nmi_backtrace.c:101
  nmi_trigger_cpumask_backtrace+0x1be/0x236 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:204 [inline]
  watchdog+0x9b7/0xec0 kernel/hung_task.c:288
  kthread+0x357/0x430 kernel/kthread.c:253
  ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:352
Sending NMI from CPU 0 to CPUs 1:

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