[syzbot] [block?] INFO: task hung in bdev_open

[syzbot] [block?] INFO: task hung in bdev_open

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit:    6fbf71854e2d Merge tag 'perf-tools-fixes-for-v6.10-1-2024-..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=15b4942c980000
kernel config:  https://syzkaller.appspot.com/x/.config?x=ee7b962709a5f5a5
dashboard link: https://syzkaller.appspot.com/bug?extid=5c6179f2c4f1e111df11
compiler:       Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40

Unfortunately, I don't have any reproducer for this issue yet.

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/91effa72f285/disk-6fbf7185.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/c6afe2efff99/vmlinux-6fbf7185.xz
kernel image: https://storage.googleapis.com/syzbot-assets/46aae93f5511/bzImage-6fbf7185.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+5c6179f2c4f1e111df11@syzkaller.appspotmail.com

INFO: task udevd:16174 blocked for more than 143 seconds.
      Not tainted 6.9.0-syzkaller-12400-g6fbf71854e2d #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:udevd           state:D stack:23920 pid:16174 tgid:16174 ppid:1      flags:0x00000002
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5408 [inline]
 __schedule+0x1796/0x49d0 kernel/sched/core.c:6745
 __schedule_loop kernel/sched/core.c:6822 [inline]
 schedule+0x14b/0x320 kernel/sched/core.c:6837
 schedule_preempt_disabled+0x13/0x30 kernel/sched/core.c:6894
 __mutex_lock_common kernel/locking/mutex.c:684 [inline]
 __mutex_lock+0x6a4/0xd70 kernel/locking/mutex.c:752
 bdev_open+0xe5/0xc60 block/bdev.c:897
 blkdev_open+0x20d/0x2e0 block/fops.c:615
 do_dentry_open+0x95a/0x1720 fs/open.c:955
 do_open fs/namei.c:3650 [inline]
 path_openat+0x289f/0x3280 fs/namei.c:3807
 do_filp_open+0x235/0x490 fs/namei.c:3834
 do_sys_openat2+0x13e/0x1d0 fs/open.c:1405
 do_sys_open fs/open.c:1420 [inline]
 __do_sys_openat fs/open.c:1436 [inline]
 __se_sys_openat fs/open.c:1431 [inline]
 __x64_sys_openat+0x247/0x2a0 fs/open.c:1431
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f7f09b169a4
RSP: 002b:00007fffaaf9cc90 EFLAGS: 00000246 ORIG_RAX: 0000000000000101
RAX: ffffffffffffffda RBX: 000055bf84d3cdb0 RCX: 00007f7f09b169a4
RDX: 00000000000a0800 RSI: 000055bf84d19770 RDI: 00000000ffffff9c
RBP: 000055bf84d19770 R08: 0000000000000001 R09: 7fffffffffffffff
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000000a0800
R13: 000055bf84d2b2c0 R14: 0000000000000001 R15: 000055bf84d18910
 </TASK>
INFO: task syz-executor.1:16345 blocked for more than 143 seconds.
      Not tainted 6.9.0-syzkaller-12400-g6fbf71854e2d #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz-executor.1  state:D stack:21168 pid:16345 tgid:16344 ppid:15599  flags:0x00004006
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5408 [inline]
 __schedule+0x1796/0x49d0 kernel/sched/core.c:6745
 __schedule_loop kernel/sched/core.c:6822 [inline]
 schedule+0x14b/0x320 kernel/sched/core.c:6837
 schedule_preempt_disabled+0x13/0x30 kernel/sched/core.c:6894
 __mutex_lock_common kernel/locking/mutex.c:684 [inline]
 __mutex_lock+0x6a4/0xd70 kernel/locking/mutex.c:752
 bdev_release+0x184/0x700 block/bdev.c:1080
 blkdev_release+0x15/0x20 block/fops.c:623
 __fput+0x406/0x8b0 fs/file_table.c:422
 task_work_run+0x24f/0x310 kernel/task_work.c:180
 get_signal+0x15e6/0x1740 kernel/signal.c:2681
 arch_do_signal_or_restart+0x96/0x860 arch/x86/kernel/signal.c:310
 exit_to_user_mode_loop kernel/entry/common.c:111 [inline]
 exit_to_user_mode_prepare include/linux/entry-common.h:328 [inline]
 __syscall_exit_to_user_mode_work kernel/entry/common.c:207 [inline]
 syscall_exit_to_user_mode+0xc9/0x370 kernel/entry/common.c:218
 do_syscall_64+0x100/0x230 arch/x86/entry/common.c:89
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f297527cee9
RSP: 002b:00007f297608b0c8 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: 0000000000000000 RBX: 00007f29753abf80 RCX: 00007f297527cee9
RDX: 0000000000000000 RSI: 000000000000ab03 RDI: 0000000000000006
RBP: 00007f29752c949e R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 000000000000000b R14: 00007f29753abf80 R15: 00007ffd34ac6de8
 </TASK>
INFO: task syz-executor.1:16353 blocked for more than 144 seconds.
      Not tainted 6.9.0-syzkaller-12400-g6fbf71854e2d #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz-executor.1  state:D stack:18712 pid:16353 tgid:16344 ppid:15599  flags:0x00004006
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5408 [inline]
 __schedule+0x1796/0x49d0 kernel/sched/core.c:6745


---
This report is generated by a bot. It may contain errors.
See https://goo.gl/tpsmEJ for more information about syzbot.
syzbot engineers can be reached at syzkaller@googlegroups.com.

syzbot will keep track of this issue. See:
https://goo.gl/tpsmEJ#status for how to communicate with syzbot.

If the report is already addressed, let syzbot know by replying with:
#syz fix: exact-commit-title

If you want to overwrite report's subsystems, reply with:
#syz set subsystems: new-subsystem
(See the list of subsystem names on the web dashboard)

If the report is a duplicate of another one, reply with:
#syz dup: exact-subject-of-another-report

If you want to undo deduplication, reply with:
#syz undup

Re: [syzbot] [block?] INFO: task hung in bdev_open

[syzbot]

syzbot has found a reproducer for the following issue on:

HEAD commit:    119009db2674 Merge tag 'vfs-6.15-rc3.fixes.2' of git://git..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=15cc4c70580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=a6bd70427e8b567f
dashboard link: https://syzkaller.appspot.com/bug?extid=5c6179f2c4f1e111df11
compiler:       Debian clang version 15.0.6, Debian LLD 15.0.6
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=168f7bac580000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/2c746991d9a8/disk-119009db.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/7dc89ed0561e/vmlinux-119009db.xz
kernel image: https://storage.googleapis.com/syzbot-assets/4412f446b5ee/bzImage-119009db.xz
mounted in repro: https://storage.googleapis.com/syzbot-assets/d5121c60f666/mount_0.gz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+5c6179f2c4f1e111df11@syzkaller.appspotmail.com

INFO: task udevd:5846 blocked for more than 143 seconds.
      Not tainted 6.15.0-rc2-syzkaller-00471-g119009db2674 #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:udevd           state:D stack:23512 pid:5846  tgid:5846  ppid:5202   task_flags:0x400140 flags:0x00000002
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5382 [inline]
 __schedule+0x1b33/0x51f0 kernel/sched/core.c:6767
 __schedule_loop kernel/sched/core.c:6845 [inline]
 schedule+0x163/0x360 kernel/sched/core.c:6860
 schedule_preempt_disabled+0x13/0x30 kernel/sched/core.c:6917
 __mutex_lock_common kernel/locking/mutex.c:678 [inline]
 __mutex_lock+0x805/0x10c0 kernel/locking/mutex.c:746
 bdev_open+0xf7/0xcd0 block/bdev.c:907
 blkdev_open+0x38e/0x4e0 block/fops.c:652
 do_dentry_open+0xdec/0x1960 fs/open.c:956
 vfs_open+0x3b/0x370 fs/open.c:1086
 do_open fs/namei.c:3880 [inline]
 path_openat+0x2caf/0x35d0 fs/namei.c:4039
 do_filp_open+0x284/0x4e0 fs/namei.c:4066
 do_sys_openat2+0x12b/0x1d0 fs/open.c:1429
 do_sys_open fs/open.c:1444 [inline]
 __do_sys_openat fs/open.c:1460 [inline]
 __se_sys_openat fs/open.c:1455 [inline]
 __x64_sys_openat+0x249/0x2a0 fs/open.c:1455
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xf3/0x210 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fc5ff7169a4
RSP: 002b:00007ffc6e4b2f70 EFLAGS: 00000246 ORIG_RAX: 0000000000000101
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007fc5ff7169a4
RDX: 0000000000080000 RSI: 000055b8bd28da40 RDI: 00000000ffffff9c
RBP: 000055b8bd28da40 R08: 000055b8bd2822c0 R09: 00007fc5ff7f1c10
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000080000
R13: 000055b8bd2822c0 R14: 0000000000000000 R15: 0000000000000001
 </TASK>

Showing all locks held in the system:
1 lock held by kdevtmpfs/26:
 #0: ffff88801c2e0950 (&type->i_mutex_dir_key/1){+.+.}-{4:4}, at: inode_lock_nested include/linux/fs.h:902 [inline]
 #0: ffff88801c2e0950 (&type->i_mutex_dir_key/1){+.+.}-{4:4}, at: __kern_path_locked+0x1ca/0x430 fs/namei.c:2765
1 lock held by khungtaskd/31:
 #0: ffffffff8ed3df20 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:331 [inline]
 #0: ffffffff8ed3df20 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:841 [inline]
 #0: ffffffff8ed3df20 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x30/0x180 kernel/locking/lockdep.c:6764
3 locks held by kworker/u8:2/36:
 #0: ffff88814d40b148 ((wq_completion)ipv6_addrconf){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3213 [inline]
 #0: ffff88814d40b148 ((wq_completion)ipv6_addrconf){+.+.}-{0:0}, at: process_scheduled_works+0x990/0x18e0 kernel/workqueue.c:3319
 #1: ffffc90000ad7c60 ((work_completion)(&(&ifa->dad_work)->work)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3214 [inline]
 #1: ffffc90000ad7c60 ((work_completion)(&(&ifa->dad_work)->work)){+.+.}-{0:0}, at: process_scheduled_works+0x9cb/0x18e0 kernel/workqueue.c:3319
 #2: ffffffff900eb288 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_net_lock include/linux/rtnetlink.h:130 [inline]
 #2: ffffffff900eb288 (rtnl_mutex){+.+.}-{4:4}, at: addrconf_dad_work+0x110/0x16a0 net/ipv6/addrconf.c:4195
3 locks held by kworker/u8:3/53:
 #0: ffff88801b089148 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3213 [inline]
 #0: ffff88801b089148 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_scheduled_works+0x990/0x18e0 kernel/workqueue.c:3319
 #1: ffffc90000be7c60 ((linkwatch_work).work){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3214 [inline]
 #1: ffffc90000be7c60 ((linkwatch_work).work){+.+.}-{0:0}, at: process_scheduled_works+0x9cb/0x18e0 kernel/workqueue.c:3319
 #2: ffffffff900eb288 (rtnl_mutex){+.+.}-{4:4}, at: linkwatch_event+0xe/0x60 net/core/link_watch.c:303
5 locks held by kworker/u8:7/2967:
 #0: ffff88801bef3948 ((wq_completion)netns){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3213 [inline]
 #0: ffff88801bef3948 ((wq_completion)netns){+.+.}-{0:0}, at: process_scheduled_works+0x990/0x18e0 kernel/workqueue.c:3319
 #1: ffffc9000b7d7c60 (net_cleanup_work){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3214 [inline]
 #1: ffffc9000b7d7c60 (net_cleanup_work){+.+.}-{0:0}, at: process_scheduled_works+0x9cb/0x18e0 kernel/workqueue.c:3319
 #2: ffffffff900de750 (pernet_ops_rwsem){++++}-{4:4}, at: cleanup_net+0x17c/0xd60 net/core/net_namespace.c:608
 #3: ffffffff900eb288 (rtnl_mutex){+.+.}-{4:4}, at: default_device_exit_batch+0xde/0x880 net/core/dev.c:12524
 #4: ffffffff8ed43438 (rcu_state.exp_mutex){+.+.}-{4:4}, at: exp_funnel_lock kernel/rcu/tree_exp.h:304 [inline]
 #4: ffffffff8ed43438 (rcu_state.exp_mutex){+.+.}-{4:4}, at: synchronize_rcu_expedited+0x384/0x830 kernel/rcu/tree_exp.h:998
2 locks held by kworker/u8:8/2985:
 #0: ffff88801b089148 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3213 [inline]
 #0: ffff88801b089148 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_scheduled_works+0x990/0x18e0 kernel/workqueue.c:3319
 #1: ffffc9000b9f7c60 ((work_completion)(&sub_info->work)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3214 [inline]
 #1: ffffc9000b9f7c60 ((work_completion)(&sub_info->work)){+.+.}-{0:0}, at: process_scheduled_works+0x9cb/0x18e0 kernel/workqueue.c:3319
1 lock held by udevd/5202:
 #0: ffff888143356358 (&disk->open_mutex){+.+.}-{4:4}, at: bdev_open+0xf7/0xcd0 block/bdev.c:907
2 locks held by getty/5592:
 #0: ffff88803189e0a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:243
 #1: ffffc900036e32f0 (&ldata->atomic_read_lock){+.+.}-{4:4}, at: n_tty_read+0x5bb/0x1700 drivers/tty/n_tty.c:2222
1 lock held by udevd/5846:
 #0: ffff8880254c6358 (&disk->open_mutex){+.+.}-{4:4}, at: bdev_open+0xf7/0xcd0 block/bdev.c:907
1 lock held by syz.1.17/6075:
 #0: ffff8880254c6358 (&disk->open_mutex){+.+.}-{4:4}, at: loop_reread_partitions drivers/block/loop.c:435 [inline]
 #0: ffff8880254c6358 (&disk->open_mutex){+.+.}-{4:4}, at: loop_set_status+0x7be/0xb20 drivers/block/loop.c:1243
1 lock held by syz.5.21/6507:
 #0: ffff888143356358 (&disk->open_mutex){+.+.}-{4:4}, at: bdev_release+0x17e/0x700 block/bdev.c:1090
1 lock held by syz-executor/7129:
 #0: ffff8880254c6358 (&disk->open_mutex){+.+.}-{4:4}, at: bdev_open+0xf7/0xcd0 block/bdev.c:907
1 lock held by syz-executor/7173:
 #0: ffff888143350358 (&disk->open_mutex){+.+.}-{4:4}, at: bdev_release+0x17e/0x700 block/bdev.c:1090
1 lock held by syz-executor/7195:
 #0: ffff888143352358 (&disk->open_mutex){+.+.}-{4:4}, at: bdev_release+0x17e/0x700 block/bdev.c:1090
1 lock held by syz-executor/7330:
 #0: ffff888143356358 (&disk->open_mutex){+.+.}-{4:4}, at: bdev_open+0xf7/0xcd0 block/bdev.c:907
1 lock held by syz-executor/7999:
 #0: ffff888143366358 (&disk->open_mutex){+.+.}-{4:4}, at: bdev_release+0x17e/0x700 block/bdev.c:1090
1 lock held by syz-executor/8148:
 #0: ffff8880254c6358 (&disk->open_mutex){+.+.}-{4:4}, at: bdev_open+0xf7/0xcd0 block/bdev.c:907
1 lock held by syz-executor/8358:
 #0: ffff888143350358 (&disk->open_mutex){+.+.}-{4:4}, at: bdev_open+0xf7/0xcd0 block/bdev.c:907
1 lock held by syz-executor/8620:
 #0: ffffffff900eb288 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_net_lock include/linux/rtnetlink.h:130 [inline]
 #0: ffffffff900eb288 (rtnl_mutex){+.+.}-{4:4}, at: inet6_rtm_newaddr+0x831/0x11b0 net/ipv6/addrconf.c:5028
1 lock held by syz.0.36/8685:
 #0: ffff8880254c4358 (&disk->open_mutex){+.+.}-{4:4}, at: loop_reread_partitions drivers/block/loop.c:435 [inline]
 #0: ffff8880254c4358 (&disk->open_mutex){+.+.}-{4:4}, at: loop_set_status+0x7be/0xb20 drivers/block/loop.c:1243
2 locks held by syz-executor/8944:
 #0: ffffffff9060bc38 (&ops->srcu#2){.+.+}-{0:0}, at: rcu_lock_acquire include/linux/rcupdate.h:331 [inline]
 #0: ffffffff9060bc38 (&ops->srcu#2){.+.+}-{0:0}, at: rcu_read_lock include/linux/rcupdate.h:841 [inline]
 #0: ffffffff9060bc38 (&ops->srcu#2){.+.+}-{0:0}, at: rtnl_link_ops_get+0x22/0x250 net/core/rtnetlink.c:570
 #1: ffffffff900eb288 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_lock net/core/rtnetlink.c:80 [inline]
 #1: ffffffff900eb288 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_nets_lock net/core/rtnetlink.c:341 [inline]
 #1: ffffffff900eb288 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_newlink+0xd68/0x1fe0 net/core/rtnetlink.c:4064
2 locks held by syz-executor/8961:
 #0: ffffffff900de750 (pernet_ops_rwsem){++++}-{4:4}, at: copy_net_ns+0x328/0x570 net/core/net_namespace.c:514
 #1: ffffffff900eb288 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_net_lock_killable include/linux/rtnetlink.h:145 [inline]
 #1: ffffffff900eb288 (rtnl_mutex){+.+.}-{4:4}, at: register_netdev+0x18/0x50 net/core/dev.c:11123
1 lock held by syz-executor/9091:
 #0: ffffffff900eb288 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_net_lock include/linux/rtnetlink.h:130 [inline]
 #0: ffffffff900eb288 (rtnl_mutex){+.+.}-{4:4}, at: inet_rtm_newaddr+0x406/0x1c40 net/ipv4/devinet.c:979
1 lock held by modprobe/9199:

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

NMI backtrace for cpu 0
CPU: 0 UID: 0 PID: 31 Comm: khungtaskd Not tainted 6.15.0-rc2-syzkaller-00471-g119009db2674 #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:94 [inline]
 dump_stack_lvl+0x241/0x360 lib/dump_stack.c:120
 nmi_cpu_backtrace+0x4ab/0x4e0 lib/nmi_backtrace.c:113
 nmi_trigger_cpumask_backtrace+0x198/0x320 lib/nmi_backtrace.c:62
 trigger_all_cpu_backtrace include/linux/nmi.h:158 [inline]
 check_hung_uninterruptible_tasks kernel/hung_task.c:274 [inline]
 watchdog+0x1058/0x10a0 kernel/hung_task.c:437
 kthread+0x7b7/0x940 kernel/kthread.c:464
 ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:153
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 UID: 0 PID: 13 Comm: kworker/u8:1 Not tainted 6.15.0-rc2-syzkaller-00471-g119009db2674 #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025
Workqueue: events_unbound nsim_dev_trap_report_work
RIP: 0010:lockdep_recursion_finish kernel/locking/lockdep.c:-1 [inline]
RIP: 0010:lock_release+0x204/0x3e0 kernel/locking/lockdep.c:5889
Code: c3 7f d3 4c 89 ef 4c 89 fe 48 8b 54 24 18 e8 d3 3b 00 00 48 8d 1d ac 96 c6 11 4c 8b 34 24 48 c7 c7 f1 7f 4c 8e e8 7c 56 89 0a <b8> ff ff ff ff 65 0f c1 05 af d2 c6 11 83 f8 01 0f 85 bf 00 00 00
RSP: 0000:ffffc900001273a0 EFLAGS: 00000082
RAX: 0000000000000001 RBX: ffffffff93651020 RCX: 0000000000000004
RDX: 0000000000000000 RSI: ffffffff8e4c7ff1 RDI: ffffffff8ca0e180
RBP: ffff88801c680b90 R08: ffffc9000012753f R09: 0000000000000000
R10: ffffc90000127530 R11: fffff52000024ea8 R12: 0000000000000004
R13: ffff88801c680000 R14: 0000000000000206 R15: ffffffff8ed3df20
FS:  0000000000000000(0000) GS:ffff8881250cf000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f6fb6a38440 CR3: 000000000eb38000 CR4: 00000000003526f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 rcu_lock_release include/linux/rcupdate.h:341 [inline]
 rcu_read_unlock include/linux/rcupdate.h:871 [inline]
 class_rcu_destructor include/linux/rcupdate.h:1155 [inline]
 unwind_next_frame+0x1a9f/0x23b0 arch/x86/kernel/unwind_orc.c:680
 arch_stack_walk+0x11e/0x150 arch/x86/kernel/stacktrace.c:25
 stack_trace_save+0x11a/0x1d0 kernel/stacktrace.c:122
 kasan_save_stack mm/kasan/common.c:47 [inline]
 kasan_save_track+0x3f/0x80 mm/kasan/common.c:68
 poison_kmalloc_redzone mm/kasan/common.c:377 [inline]
 __kasan_kmalloc+0x9d/0xb0 mm/kasan/common.c:394
 kasan_kmalloc include/linux/kasan.h:260 [inline]
 __do_kmalloc_node mm/slub.c:4341 [inline]
 __kmalloc_node_track_caller_noprof+0x295/0x4d0 mm/slub.c:4360
 kmalloc_reserve+0x111/0x2a0 net/core/skbuff.c:599
 __alloc_skb+0x1f2/0x480 net/core/skbuff.c:668
 alloc_skb include/linux/skbuff.h:1340 [inline]
 nsim_dev_trap_skb_build drivers/net/netdevsim/dev.c:748 [inline]
 nsim_dev_trap_report drivers/net/netdevsim/dev.c:805 [inline]
 nsim_dev_trap_report_work+0x260/0xb50 drivers/net/netdevsim/dev.c:851
 process_one_work kernel/workqueue.c:3238 [inline]
 process_scheduled_works+0xac3/0x18e0 kernel/workqueue.c:3319
 worker_thread+0x870/0xd50 kernel/workqueue.c:3400
 kthread+0x7b7/0x940 kernel/kthread.c:464
 ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:153
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>


---
If you want syzbot to run the reproducer, reply with:
#syz test: git://repo/address.git branch-or-commit-hash
If you attach or paste a git patch, syzbot will apply it before testing.

Re: [syzbot] [block?] INFO: task hung in bdev_open

[syzbot]

syzbot has found a reproducer for the following issue on:

HEAD commit:    9f35e33144ae x86/its: Fix build errors when CONFIG_MODULES=n
git tree:       upstream
console+strace: https://syzkaller.appspot.com/x/log.txt?x=10639af4580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=bc44e21a0b824ef8
dashboard link: https://syzkaller.appspot.com/bug?extid=5c6179f2c4f1e111df11
compiler:       Debian clang version 20.1.2 (++20250402124445+58df0ef89dd6-1~exp1~20250402004600.97), Debian LLD 20.1.2
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=115c4e70580000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=166c2f68580000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/0143554b1db5/disk-9f35e331.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/ccf3a30abae2/vmlinux-9f35e331.xz
kernel image: https://storage.googleapis.com/syzbot-assets/6e205d989271/bzImage-9f35e331.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+5c6179f2c4f1e111df11@syzkaller.appspotmail.com

INFO: task udevd:5194 blocked for more than 143 seconds.
      Not tainted 6.15.0-rc6-syzkaller-00052-g9f35e33144ae #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:udevd           state:D stack:24824 pid:5194  tgid:5194  ppid:1      task_flags:0x400140 flags:0x00000002
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5382 [inline]
 __schedule+0x16e2/0x4cd0 kernel/sched/core.c:6767
 __schedule_loop kernel/sched/core.c:6845 [inline]
 schedule+0x165/0x360 kernel/sched/core.c:6860
 schedule_preempt_disabled+0x13/0x30 kernel/sched/core.c:6917
 __mutex_lock_common kernel/locking/mutex.c:678 [inline]
 __mutex_lock+0x724/0xe80 kernel/locking/mutex.c:746
 bdev_open+0xe0/0xd30 block/bdev.c:945
 blkdev_open+0x3a8/0x510 block/fops.c:652
 do_dentry_open+0xdf3/0x1970 fs/open.c:956
 vfs_open+0x3b/0x340 fs/open.c:1086
 do_open fs/namei.c:3880 [inline]
 path_openat+0x2ee5/0x3830 fs/namei.c:4039
 do_filp_open+0x1fa/0x410 fs/namei.c:4066
 do_sys_openat2+0x121/0x1c0 fs/open.c:1429
 do_sys_open fs/open.c:1444 [inline]
 __do_sys_openat fs/open.c:1460 [inline]
 __se_sys_openat fs/open.c:1455 [inline]
 __x64_sys_openat+0x138/0x170 fs/open.c:1455
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xf6/0x210 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fdfe28a7407
RSP: 002b:00007ffefe105d00 EFLAGS: 00000202 ORIG_RAX: 0000000000000101
RAX: ffffffffffffffda RBX: 00007fdfe2f55880 RCX: 00007fdfe28a7407
RDX: 00000000000a0800 RSI: 000056326f6fe3e0 RDI: ffffffffffffff9c
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000202 R12: 0000000000000000
R13: 000056324ea0e100 R14: 0000000000000000 R15: 00007ffefe105f90
 </TASK>
INFO: task syz-executor268:5876 blocked for more than 143 seconds.
      Not tainted 6.15.0-rc6-syzkaller-00052-g9f35e33144ae #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz-executor268 state:D stack:27096 pid:5876  tgid:5872  ppid:5852   task_flags:0x400140 flags:0x00004006
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5382 [inline]
 __schedule+0x16e2/0x4cd0 kernel/sched/core.c:6767
 __schedule_loop kernel/sched/core.c:6845 [inline]
 schedule+0x165/0x360 kernel/sched/core.c:6860
 schedule_preempt_disabled+0x13/0x30 kernel/sched/core.c:6917
 __mutex_lock_common kernel/locking/mutex.c:678 [inline]
 __mutex_lock+0x724/0xe80 kernel/locking/mutex.c:746
 bdev_release+0x1a9/0x650 block/bdev.c:1128
 blkdev_release+0x15/0x20 block/fops.c:660
 __fput+0x44c/0xa70 fs/file_table.c:465
 task_work_run+0x1d4/0x260 kernel/task_work.c:227
 ptrace_notify+0x281/0x2c0 kernel/signal.c:2520
 ptrace_report_syscall include/linux/ptrace.h:415 [inline]
 ptrace_report_syscall_exit include/linux/ptrace.h:477 [inline]
 syscall_exit_work+0xc2/0x1d0 kernel/entry/common.c:173
 syscall_exit_to_user_mode_prepare+0x6f/0xe0 kernel/entry/common.c:200
 __syscall_exit_to_user_mode_work kernel/entry/common.c:205 [inline]
 syscall_exit_to_user_mode+0x12/0x120 kernel/entry/common.c:218
 do_syscall_64+0x103/0x210 arch/x86/entry/syscall_64.c:100
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f4f6252f929
RSP: 002b:00007f4f624e5218 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: 0000000000000000 RBX: 00007f4f625b7328 RCX: 00007f4f6252f929
RDX: 0000000000000000 RSI: 000000000000ab03 RDI: 0000000000000003
RBP: 00007f4f625b7320 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007f4f6258435c
R13: 64626e2f7665642f R14: 0000200000000040 R15: 0000000080000000
 </TASK>

Showing all locks held in the system:
1 lock held by khungtaskd/31:
 #0: ffffffff8df3dce0 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:331 [inline]
 #0: ffffffff8df3dce0 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:841 [inline]
 #0: ffffffff8df3dce0 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x2e/0x180 kernel/locking/lockdep.c:6764
2 locks held by kworker/u8:3/53:
 #0: ffff8880b8839b58 (&rq->__lock){-.-.}-{2:2}, at: raw_spin_rq_lock_nested+0x2a/0x140 kernel/sched/core.c:605
 #1: ffff8880b8823b08 (&per_cpu_ptr(group->pcpu, cpu)->seq){-.-.}-{0:0}, at: psi_task_switch+0x318/0x6d0 kernel/sched/psi.c:975
1 lock held by udevd/5194:
 #0: ffff888024977358 (&disk->open_mutex){+.+.}-{4:4}, at: bdev_open+0xe0/0xd30 block/bdev.c:945
2 locks held by getty/5587:
 #0: ffff8880303d60a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:243
 #1: ffffc90002ffe2f0 (&ldata->atomic_read_lock){+.+.}-{4:4}, at: n_tty_read+0x43e/0x1400 drivers/tty/n_tty.c:2222
1 lock held by udevd/5861:
 #0: ffff888024977358 (&disk->open_mutex){+.+.}-{4:4}, at: bdev_open+0xe0/0xd30 block/bdev.c:945
1 lock held by syz-executor268/5876:
 #0: ffff888024977358 (&disk->open_mutex){+.+.}-{4:4}, at: bdev_release+0x1a9/0x650 block/bdev.c:1128

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

NMI backtrace for cpu 1
CPU: 1 UID: 0 PID: 31 Comm: khungtaskd Not tainted 6.15.0-rc6-syzkaller-00052-g9f35e33144ae #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
Call Trace:
 <TASK>
 dump_stack_lvl+0x189/0x250 lib/dump_stack.c:120
 nmi_cpu_backtrace+0x39e/0x3d0 lib/nmi_backtrace.c:113
 nmi_trigger_cpumask_backtrace+0x17a/0x300 lib/nmi_backtrace.c:62
 trigger_all_cpu_backtrace include/linux/nmi.h:158 [inline]
 check_hung_uninterruptible_tasks kernel/hung_task.c:274 [inline]
 watchdog+0xfee/0x1030 kernel/hung_task.c:437
 kthread+0x711/0x8a0 kernel/kthread.c:464
 ret_from_fork+0x4e/0x80 arch/x86/kernel/process.c:153
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0 skipped: idling at constant_test_bit arch/x86/include/asm/bitops.h:206 [inline]
NMI backtrace for cpu 0 skipped: idling at arch_test_bit arch/x86/include/asm/bitops.h:238 [inline]
NMI backtrace for cpu 0 skipped: idling at tif_test_bit include/linux/thread_info.h:192 [inline]
NMI backtrace for cpu 0 skipped: idling at tif_need_resched include/linux/thread_info.h:208 [inline]
NMI backtrace for cpu 0 skipped: idling at current_clr_polling_and_test include/linux/sched/idle.h:79 [inline]
NMI backtrace for cpu 0 skipped: idling at default_idle_call+0x1b/0xb0 kernel/sched/idle.c:111


---
If you want syzbot to run the reproducer, reply with:
#syz test: git://repo/address.git branch-or-commit-hash
If you attach or paste a git patch, syzbot will apply it before testing.