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INFO: task hung in lock_mount

Status: upstream: reported C repro on 2024/04/25 09:15
Bug presence: origin:upstream
[Documentation on labels]
Reported-by: syzbot+186cfa1ab5ab413e8877@syzkaller.appspotmail.com
First crash: 10d, last: 10d
▶ ▼ Bug presence (1)
Date Name Commit Repro Result
2024/04/26 upstream (ToT) c942a0cd3603 C [report] INFO: task hung in __fdget_pos
▶ ▼ Similar bugs (10)
Kernel Title Repro Cause bisect Fix bisect Count Last Reported Patched Status
linux-4.19 INFO: task hung in lock_mount (4) 6 902d 1016d 0/1 auto-closed as invalid on 2022/03/15 09:18
android-49 INFO: task hung in lock_mount C 103 1733d 1851d 0/3 public: reported C repro on 2019/04/11 08:44
linux-4.19 INFO: task hung in lock_mount 5 1577d 1707d 0/1 auto-closed as invalid on 2020/05/09 01:51
upstream INFO: task hung in lock_mount nilfs C error error 1238 381d 2196d 22/26 fixed on 2023/06/08 14:41
linux-4.19 INFO: task hung in lock_mount (2) 2 1414d 1420d 0/1 auto-closed as invalid on 2020/10/18 21:28
android-44 INFO: task hung in lock_mount C 4 2130d 1849d 0/2 public: reported C repro on 2019/04/13 00:00
linux-4.19 INFO: task hung in lock_mount (3) 1 1180d 1180d 0/1 auto-closed as invalid on 2021/06/09 16:09
linux-4.14 INFO: task hung in lock_mount 2 1609d 1609d 0/1 auto-closed as invalid on 2020/04/07 06:26
upstream INFO: task can't die in lock_mount fs C 75 895d 1232d 0/26 closed as dup on 2021/01/18 10:01
upstream INFO: task can't die in iget5_locked fuse 7 1165d 1190d 20/26 fixed on 2021/04/09 19:46

Sample crash report:
INFO: task syz-executor245:3534 blocked for more than 143 seconds.
      Not tainted 5.15.156-syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz-executor245 state:D stack:25824 pid: 3534 ppid:  3531 flags:0x00004006
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5030 [inline]
 __schedule+0x12c4/0x45b0 kernel/sched/core.c:6376
 schedule+0x11b/0x1f0 kernel/sched/core.c:6459
 rwsem_down_write_slowpath+0xf0c/0x16a0 kernel/locking/rwsem.c:1165
 inode_lock include/linux/fs.h:789 [inline]
 lock_mount+0x62/0x2c0 fs/namespace.c:2248
 do_new_mount_fc fs/namespace.c:2942 [inline]
 do_new_mount+0x433/0xb40 fs/namespace.c:3007
 do_mount fs/namespace.c:3348 [inline]
 __do_sys_mount fs/namespace.c:3556 [inline]
 __se_sys_mount+0x2d5/0x3c0 fs/namespace.c:3533
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x3b/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x66/0xd0
RIP: 0033:0x7f34356fa26a
RSP: 002b:00007fff46c5c9d8 EFLAGS: 00000286 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 00007fff46c5c9f0 RCX: 00007f34356fa26a
RDX: 0000000020001500 RSI: 0000000020000140 RDI: 00007fff46c5c9f0
RBP: 0000000000000005 R08: 00007fff46c5ca30 R09: 00000000000014f8
R10: 0000000000000800 R11: 0000000000000286 R12: 0000000000000800
R13: 00007fff46c5ca30 R14: 0000000000000004 R15: 0000000000020000
 </TASK>
INFO: task syz-executor245:3535 blocked for more than 143 seconds.
      Not tainted 5.15.156-syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz-executor245 state:D stack:24864 pid: 3535 ppid:  3530 flags:0x00004006
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5030 [inline]
 __schedule+0x12c4/0x45b0 kernel/sched/core.c:6376
 schedule+0x11b/0x1f0 kernel/sched/core.c:6459
 rwsem_down_write_slowpath+0xf0c/0x16a0 kernel/locking/rwsem.c:1165
 inode_lock include/linux/fs.h:789 [inline]
 lock_mount+0x21b/0x2c0 fs/namespace.c:2248
 do_new_mount_fc fs/namespace.c:2942 [inline]
 do_new_mount+0x433/0xb40 fs/namespace.c:3007
 do_mount fs/namespace.c:3348 [inline]
 __do_sys_mount fs/namespace.c:3556 [inline]
 __se_sys_mount+0x2d5/0x3c0 fs/namespace.c:3533
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x3b/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x66/0xd0
RIP: 0033:0x7f34356fa26a
RSP: 002b:00007fff46c5c9d8 EFLAGS: 00000286 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 00007fff46c5c9f0 RCX: 00007f34356fa26a
RDX: 0000000020001500 RSI: 0000000020000140 RDI: 00007fff46c5c9f0
RBP: 0000000000000005 R08: 00007fff46c5ca30 R09: 00000000000014f8
R10: 0000000000000800 R11: 0000000000000286 R12: 0000000000000800
R13: 00007fff46c5ca30 R14: 0000000000000004 R15: 0000000000020000
 </TASK>
INFO: task syz-executor245:3538 blocked for more than 143 seconds.
      Not tainted 5.15.156-syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz-executor245 state:D stack:24304 pid: 3538 ppid:  3533 flags:0x00004006
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5030 [inline]
 __schedule+0x12c4/0x45b0 kernel/sched/core.c:6376
 schedule+0x11b/0x1f0 kernel/sched/core.c:6459
 rwsem_down_write_slowpath+0xf0c/0x16a0 kernel/locking/rwsem.c:1165
 inode_lock include/linux/fs.h:789 [inline]
 lock_mount+0x21b/0x2c0 fs/namespace.c:2248
 do_new_mount_fc fs/namespace.c:2942 [inline]
 do_new_mount+0x433/0xb40 fs/namespace.c:3007
 do_mount fs/namespace.c:3348 [inline]
 __do_sys_mount fs/namespace.c:3556 [inline]
 __se_sys_mount+0x2d5/0x3c0 fs/namespace.c:3533
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x3b/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x66/0xd0
RIP: 0033:0x7f34356fa26a
RSP: 002b:00007fff46c5c9d8 EFLAGS: 00000286 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 00007fff46c5c9f0 RCX: 00007f34356fa26a
RDX: 0000000020001500 RSI: 0000000020000140 RDI: 00007fff46c5c9f0
RBP: 0000000000000005 R08: 00007fff46c5ca30 R09: 00000000000014f8
R10: 0000000000000800 R11: 0000000000000286 R12: 0000000000000800
R13: 00007fff46c5ca30 R14: 0000000000000004 R15: 0000000000020000
 </TASK>
INFO: task syz-executor245:3539 blocked for more than 144 seconds.
      Not tainted 5.15.156-syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz-executor245 state:D stack:24960 pid: 3539 ppid:  3532 flags:0x00004006
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5030 [inline]
 __schedule+0x12c4/0x45b0 kernel/sched/core.c:6376
 schedule+0x11b/0x1f0 kernel/sched/core.c:6459
 rwsem_down_write_slowpath+0xf0c/0x16a0 kernel/locking/rwsem.c:1165
 inode_lock include/linux/fs.h:789 [inline]
 lock_mount+0x62/0x2c0 fs/namespace.c:2248
 do_new_mount_fc fs/namespace.c:2942 [inline]
 do_new_mount+0x433/0xb40 fs/namespace.c:3007
 do_mount fs/namespace.c:3348 [inline]
 __do_sys_mount fs/namespace.c:3556 [inline]
 __se_sys_mount+0x2d5/0x3c0 fs/namespace.c:3533
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x3b/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x66/0xd0
RIP: 0033:0x7f34356fa26a
RSP: 002b:00007fff46c5c9d8 EFLAGS: 00000286 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 00007fff46c5c9f0 RCX: 00007f34356fa26a
RDX: 0000000020001500 RSI: 0000000020000140 RDI: 00007fff46c5c9f0
RBP: 0000000000000005 R08: 00007fff46c5ca30 R09: 00000000000014f8
R10: 0000000000000800 R11: 0000000000000286 R12: 0000000000000800
R13: 00007fff46c5ca30 R14: 0000000000000004 R15: 0000000000020000
 </TASK>

Showing all locks held in the system:
1 lock held by khungtaskd/27:
 #0: ffffffff8c91fb20 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire+0x0/0x30
2 locks held by getty/3263:
 #0: ffff888024765098 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x21/0x70 drivers/tty/tty_ldisc.c:252
 #1: ffffc90002bab2e8 (&ldata->atomic_read_lock){+.+.}-{3:3}, at: n_tty_read+0x6af/0x1db0 drivers/tty/n_tty.c:2158
1 lock held by syz-executor245/3534:
 #0: ffff8880712102b0 (&sb->s_type->i_mutex_key#15){+.+.}-{3:3}, at: inode_lock include/linux/fs.h:789 [inline]
 #0: ffff8880712102b0 (&sb->s_type->i_mutex_key#15){+.+.}-{3:3}, at: lock_mount+0x62/0x2c0 fs/namespace.c:2248
1 lock held by syz-executor245/3535:
 #0: ffff8880712102b0 (&sb->s_type->i_mutex_key#15){+.+.}-{3:3}, at: inode_lock include/linux/fs.h:789 [inline]
 #0: ffff8880712102b0 (&sb->s_type->i_mutex_key#15){+.+.}-{3:3}, at: lock_mount+0x21b/0x2c0 fs/namespace.c:2248
3 locks held by syz-executor245/3536:
1 lock held by syz-executor245/3538:
 #0: ffff8880712102b0 (&sb->s_type->i_mutex_key#15){+.+.}-{3:3}, at: inode_lock include/linux/fs.h:789 [inline]
 #0: ffff8880712102b0 (&sb->s_type->i_mutex_key#15){+.+.}-{3:3}, at: lock_mount+0x21b/0x2c0 fs/namespace.c:2248
1 lock held by syz-executor245/3539:
 #0: ffff8880712102b0 (&sb->s_type->i_mutex_key#15){+.+.}-{3:3}, at: inode_lock include/linux/fs.h:789 [inline]
 #0: ffff8880712102b0 (&sb->s_type->i_mutex_key#15){+.+.}-{3:3}, at: lock_mount+0x62/0x2c0 fs/namespace.c:2248

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

NMI backtrace for cpu 0
CPU: 0 PID: 27 Comm: khungtaskd Not tainted 5.15.156-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/27/2024
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0x1e3/0x2d0 lib/dump_stack.c:106
 nmi_cpu_backtrace+0x46a/0x4a0 lib/nmi_backtrace.c:111
 nmi_trigger_cpumask_backtrace+0x181/0x2a0 lib/nmi_backtrace.c:62
 trigger_all_cpu_backtrace include/linux/nmi.h:148 [inline]
 check_hung_uninterruptible_tasks kernel/hung_task.c:210 [inline]
 watchdog+0xe72/0xeb0 kernel/hung_task.c:295
 kthread+0x3f6/0x4f0 kernel/kthread.c:334
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:300
 </TASK>
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 PID: 3536 Comm: syz-executor245 Not tainted 5.15.156-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/27/2024
RIP: 0010:lock_is_held_type+0x122/0x180 kernel/locking/lockdep.c:5668
Code: e8 83 11 00 00 b8 ff ff ff ff 65 0f c1 05 f6 d7 e4 75 83 f8 01 75 40 48 c7 04 24 00 00 00 00 9c 8f 04 24 f7 04 24 00 02 00 00 <75> 46 41 f7 c4 00 02 00 00 74 01 fb 65 48 8b 04 25 28 00 00 00 48
RSP: 0018:ffffc90002c17478 EFLAGS: 00000046
RAX: 0000000000000001 RBX: 0000000000000003 RCX: ffff888078758000
RDX: 0000000000000000 RSI: ffffffff8a8b3c20 RDI: ffffffff8ad8f380
RBP: 0000000000000000 R08: ffffffff81ac4b6e R09: fffff9400037f0c9
R10: 0000000000000000 R11: dffffc0000000001 R12: 0000000000000246
R13: ffff888078758000 R14: 00000000ffffffff R15: ffffffff8c91faa0
FS:  0000555555950380(0000) GS:ffff8880b9b00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000564cf2431600 CR3: 000000001ae7f000 CR4: 00000000003506e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <NMI>
 </NMI>
 <TASK>
 lock_is_held include/linux/lockdep.h:287 [inline]
 ___might_sleep+0xf1/0x6a0 kernel/sched/core.c:9592
 __getblk_gfp+0x43/0xaf0 fs/buffer.c:1334
 __bread_gfp+0x2a/0x390 fs/buffer.c:1381
 sb_bread include/linux/buffer_head.h:337 [inline]
 exfat_get_dentry+0x678/0x970 fs/exfat/dir.c:741
 exfat_readdir fs/exfat/dir.c:122 [inline]
 exfat_iterate+0xc09/0x34a0 fs/exfat/dir.c:258
 iterate_dir+0x224/0x570
 __do_sys_getdents64 fs/readdir.c:369 [inline]
 __se_sys_getdents64+0x209/0x4f0 fs/readdir.c:354
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x3b/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x66/0xd0
RIP: 0033:0x7f34356f8ed9
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 f1 17 00 00 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 73 01 c3 48 c7 c1 b8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fff46c5cb68 EFLAGS: 00000246 ORIG_RAX: 00000000000000d9
RAX: ffffffffffffffda RBX: 00007f3435742095 RCX: 00007f34356f8ed9
RDX: 00000000000000ca RSI: 00000000200001c0 RDI: 0000000000000005
RBP: 0030656c69662f2e R08: 0000555555951378 R09: 0000555555951378
R10: 00000000000014f8 R11: 0000000000000246 R12: 0000000000000001
R13: 00007fff46c5cba0 R14: 00007fff46c5cb8c R15: 00007f343574203b
 </TASK>
INFO: NMI handler (nmi_cpu_backtrace_handler) took too long to run: 1.346 msecs

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2024/04/25 09:15 linux-5.15.y c52b9710c83d 8bdc0f22 .config console log report syz C [disk image] [vmlinux] [kernel image] [mounted in repro] ci2-linux-5-15-kasan INFO: task hung in lock_mount
* Struck through repros no longer work on HEAD.