syzbot


INFO: task hung in lock_mount

Status: auto-closed as invalid on 2020/04/07 06:26
Reported-by: syzbot+be9f2215577e0744f2e5@syzkaller.appspotmail.com
First crash: 937d, last: 936d
similar bugs (7):
Kernel Title Repro Cause bisect Fix bisect Count Last Reported Patched Status
linux-4.19 INFO: task hung in lock_mount (4) 6 229d 344d 0/1 auto-closed as invalid on 2022/03/15 09:18
android-49 INFO: task hung in lock_mount C 103 1061d 1178d 0/3 public: reported C repro on 2019/04/11 08:44
linux-4.19 INFO: task hung in lock_mount 5 905d 1035d 0/1 auto-closed as invalid on 2020/05/09 01:51
upstream INFO: task hung in lock_mount C error error 1232 210d 1524d 0/22 upstream: reported C repro on 2018/04/30 17:46
linux-4.19 INFO: task hung in lock_mount (2) 2 742d 748d 0/1 auto-closed as invalid on 2020/10/18 21:28
android-44 INFO: task hung in lock_mount C 4 1458d 1177d 0/2 public: reported C repro on 2019/04/13 00:00
linux-4.19 INFO: task hung in lock_mount (3) 1 508d 508d 0/1 auto-closed as invalid on 2021/06/09 16:09

Sample crash report:
bond0 (unregistering): Released all slaves
audit: type=1400 audit(1575872701.474:75): avc:  denied  { map } for  pid=9159 comm="sh" path="/bin/dash" dev="sda1" ino=1473 scontext=system_u:system_r:insmod_t:s0-s0:c0.c1023 tcontext=system_u:object_r:file_t:s0 tclass=file permissive=1
INFO: task syz-executor.2:9145 blocked for more than 140 seconds.
      Not tainted 4.14.158-syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor.2  D28496  9145   7014 0x00000004
Call Trace:
 context_switch kernel/sched/core.c:2808 [inline]
 __schedule+0x7b8/0x1cd0 kernel/sched/core.c:3384
 schedule+0x92/0x1c0 kernel/sched/core.c:3428
 __rwsem_down_write_failed_common kernel/locking/rwsem-xadd.c:588 [inline]
 rwsem_down_write_failed+0x5ce/0xb50 kernel/locking/rwsem-xadd.c:617
 call_rwsem_down_write_failed+0x17/0x30 arch/x86/lib/rwsem.S:105
 __down_write arch/x86/include/asm/rwsem.h:126 [inline]
 down_write+0x53/0x90 kernel/locking/rwsem.c:56
 inode_lock include/linux/fs.h:718 [inline]
 lock_mount+0x8c/0x2c0 fs/namespace.c:2119
 do_add_mount+0x27/0x350 fs/namespace.c:2496
 do_new_mount fs/namespace.c:2563 [inline]
 do_mount+0x1307/0x27d0 fs/namespace.c:2879
 SYSC_mount fs/namespace.c:3095 [inline]
 SyS_mount+0xab/0x120 fs/namespace.c:3072
 do_syscall_64+0x1e8/0x640 arch/x86/entry/common.c:292
 entry_SYSCALL_64_after_hwframe+0x42/0xb7
RIP: 0033:0x45a6f9
RSP: 002b:00007f3ddcd7fc78 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 0000000000000005 RCX: 000000000045a6f9
RDX: 00000000200008c0 RSI: 0000000020000000 RDI: 0000000000000000
RBP: 000000000075bfc8 R08: 0000000020000800 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007f3ddcd806d4
R13: 00000000004c7aa2 R14: 00000000004de940 R15: 00000000ffffffff
INFO: task syz-executor.2:9146 blocked for more than 140 seconds.
      Not tainted 4.14.158-syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor.2  D29744  9146   7014 0x00000004
Call Trace:
 context_switch kernel/sched/core.c:2808 [inline]
 __schedule+0x7b8/0x1cd0 kernel/sched/core.c:3384
 schedule+0x92/0x1c0 kernel/sched/core.c:3428
 __rwsem_down_write_failed_common kernel/locking/rwsem-xadd.c:588 [inline]
 rwsem_down_write_failed+0x5ce/0xb50 kernel/locking/rwsem-xadd.c:617
 call_rwsem_down_write_failed+0x17/0x30 arch/x86/lib/rwsem.S:105
 __down_write arch/x86/include/asm/rwsem.h:126 [inline]
 down_write+0x53/0x90 kernel/locking/rwsem.c:56
 inode_lock include/linux/fs.h:718 [inline]
 do_last fs/namei.c:3328 [inline]
 path_openat+0xfab/0x3f70 fs/namei.c:3566
 do_filp_open+0x18e/0x250 fs/namei.c:3600
 do_sys_open+0x2c5/0x430 fs/open.c:1084
 SYSC_open fs/open.c:1102 [inline]
 SyS_open fs/open.c:1097 [inline]
 SYSC_creat fs/open.c:1142 [inline]
 SyS_creat+0x27/0x30 fs/open.c:1140
 do_syscall_64+0x1e8/0x640 arch/x86/entry/common.c:292
 entry_SYSCALL_64_after_hwframe+0x42/0xb7
RIP: 0033:0x45a6f9
RSP: 002b:00007f3ddcd5ec78 EFLAGS: 00000246 ORIG_RAX: 0000000000000055
RAX: ffffffffffffffda RBX: 0000000000000002 RCX: 000000000045a6f9
RDX: 0000000000000000 RSI: 0000000000000188 RDI: 0000000020000300
RBP: 000000000075c070 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007f3ddcd5f6d4
R13: 00000000004c0fa8 R14: 00000000004d4da0 R15: 00000000ffffffff

Showing all locks held in the system:
1 lock held by khungtaskd/1045:
 #0:  (tasklist_lock){.+.+}, at: [<ffffffff8148c8a8>] debug_show_all_locks+0x7f/0x21f kernel/locking/lockdep.c:4544
1 lock held by rsyslogd/6843:
 #0:  (&f->f_pos_lock){+.+.}, at: [<ffffffff81966a1b>] __fdget_pos+0xab/0xd0 fs/file.c:769
2 locks held by getty/6965:
 #0:  (&tty->ldisc_sem){++++}, at: [<ffffffff866549c3>] ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:376
 #1:  (&ldata->atomic_read_lock){+.+.}, at: [<ffffffff83490d76>] n_tty_read+0x1e6/0x17b0 drivers/tty/n_tty.c:2156
2 locks held by getty/6966:
 #0:  (&tty->ldisc_sem){++++}, at: [<ffffffff866549c3>] ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:376
 #1:  (&ldata->atomic_read_lock){+.+.}, at: [<ffffffff83490d76>] n_tty_read+0x1e6/0x17b0 drivers/tty/n_tty.c:2156
2 locks held by getty/6967:
 #0:  (&tty->ldisc_sem){++++}, at: [<ffffffff866549c3>] ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:376
 #1:  (&ldata->atomic_read_lock){+.+.}, at: [<ffffffff83490d76>] n_tty_read+0x1e6/0x17b0 drivers/tty/n_tty.c:2156
2 locks held by getty/6968:
 #0:  (&tty->ldisc_sem){++++}, at: [<ffffffff866549c3>] ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:376
 #1:  (&ldata->atomic_read_lock){+.+.}, at: [<ffffffff83490d76>] n_tty_read+0x1e6/0x17b0 drivers/tty/n_tty.c:2156
2 locks held by getty/6969:
 #0:  (&tty->ldisc_sem){++++}, at: [<ffffffff866549c3>] ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:376
 #1:  (&ldata->atomic_read_lock){+.+.}, at: [<ffffffff83490d76>] n_tty_read+0x1e6/0x17b0 drivers/tty/n_tty.c:2156
2 locks held by getty/6970:
 #0:  (&tty->ldisc_sem){++++}, at: [<ffffffff866549c3>] ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:376
 #1:  (&ldata->atomic_read_lock){+.+.}, at: [<ffffffff83490d76>] n_tty_read+0x1e6/0x17b0 drivers/tty/n_tty.c:2156
2 locks held by getty/6971:
 #0:  (&tty->ldisc_sem){++++}, at: [<ffffffff866549c3>] ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:376
 #1:  (&ldata->atomic_read_lock){+.+.}, at: [<ffffffff83490d76>] n_tty_read+0x1e6/0x17b0 drivers/tty/n_tty.c:2156
2 locks held by syz-executor.2/9077:
 #0:  (sb_writers#16){.+.+}, at: [<ffffffff8196fd1f>] sb_start_write include/linux/fs.h:1548 [inline]
 #0:  (sb_writers#16){.+.+}, at: [<ffffffff8196fd1f>] mnt_want_write+0x3f/0xb0 fs/namespace.c:386
 #1:  (&sb->s_type->i_mutex_key#21){+.+.}, at: [<ffffffff8192ebfb>] inode_lock include/linux/fs.h:718 [inline]
 #1:  (&sb->s_type->i_mutex_key#21){+.+.}, at: [<ffffffff8192ebfb>] do_last fs/namei.c:3328 [inline]
 #1:  (&sb->s_type->i_mutex_key#21){+.+.}, at: [<ffffffff8192ebfb>] path_openat+0xfab/0x3f70 fs/namei.c:3566
1 lock held by syz-executor.2/9145:
 #0:  (&sb->s_type->i_mutex_key#21){+.+.}, at: [<ffffffff8197150c>] inode_lock include/linux/fs.h:718 [inline]
 #0:  (&sb->s_type->i_mutex_key#21){+.+.}, at: [<ffffffff8197150c>] lock_mount+0x8c/0x2c0 fs/namespace.c:2119
2 locks held by syz-executor.2/9146:
 #0:  (sb_writers#16){.+.+}, at: [<ffffffff8196fd1f>] sb_start_write include/linux/fs.h:1548 [inline]
 #0:  (sb_writers#16){.+.+}, at: [<ffffffff8196fd1f>] mnt_want_write+0x3f/0xb0 fs/namespace.c:386
 #1:  (&sb->s_type->i_mutex_key#21){+.+.}, at: [<ffffffff8192ebfb>] inode_lock include/linux/fs.h:718 [inline]
 #1:  (&sb->s_type->i_mutex_key#21){+.+.}, at: [<ffffffff8192ebfb>] do_last fs/namei.c:3328 [inline]
 #1:  (&sb->s_type->i_mutex_key#21){+.+.}, at: [<ffffffff8192ebfb>] path_openat+0xfab/0x3f70 fs/namei.c:3566

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

NMI backtrace for cpu 1
CPU: 1 PID: 1045 Comm: khungtaskd Not tainted 4.14.158-syzkaller #0
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+0x142/0x197 lib/dump_stack.c:58
 nmi_cpu_backtrace.cold+0x57/0x94 lib/nmi_backtrace.c:101
 nmi_trigger_cpumask_backtrace+0x141/0x189 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:140 [inline]
 check_hung_uninterruptible_tasks kernel/hung_task.c:195 [inline]
 watchdog+0x5e7/0xb90 kernel/hung_task.c:274
 kthread+0x319/0x430 kernel/kthread.c:232
 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:404
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0 skipped: idling at pc 0xffffffff866554ae

Crashes (2):
Manager Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Title
ci2-linux-4-14 2019/12/09 06:26 linux-4.14.y a844dc4c5442 1508f453 .config log report
ci2-linux-4-14 2019/12/08 11:53 linux-4.14.y a844dc4c5442 1508f453 .config log report