syzbot

INFO: task syz.4.366:8888 blocked for more than 143 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.4.366       state:D stack:25696 pid:8888  tgid:8887  ppid:8034   task_flags:0x400140 flags:0x00080002
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5298 [inline]
 __schedule+0x1553/0x5240 kernel/sched/core.c:6911
 __schedule_loop kernel/sched/core.c:6993 [inline]
 rt_mutex_schedule+0x76/0xf0 kernel/sched/core.c:7289
 rt_mutex_slowlock_block kernel/locking/rtmutex.c:1647 [inline]
 __rt_mutex_slowlock kernel/locking/rtmutex.c:1721 [inline]
 __rt_mutex_slowlock_locked+0x1f8f/0x25c0 kernel/locking/rtmutex.c:1760
 __rwbase_read_lock+0xc3/0x180 kernel/locking/rwbase_rt.c:114
 rwbase_read_lock kernel/locking/rwbase_rt.c:147 [inline]
 __down_read kernel/locking/rwsem.c:1466 [inline]
 down_read+0x132/0x200 kernel/locking/rwsem.c:1539
 __super_lock fs/super.c:60 [inline]
 super_lock+0x2d6/0x3d0 fs/super.c:122
 user_get_super+0xc8/0x120 fs/super.c:1001
 quotactl_block fs/quota/quota.c:889 [inline]
 __do_sys_quotactl fs/quota/quota.c:955 [inline]
 __se_sys_quotactl+0x540/0x9e0 fs/quota/quota.c:917
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x14d/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fe1fa24c799
RSP: 002b:00007fe1f849e028 EFLAGS: 00000246 ORIG_RAX: 00000000000000b3
RAX: ffffffffffffffda RBX: 00007fe1fa4c5fa0 RCX: 00007fe1fa24c799
RDX: ffffffffffffffff RSI: 0000200000000100 RDI: ffffffff80000702
RBP: 00007fe1fa2e2c99 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fe1fa4c6038 R14: 00007fe1fa4c5fa0 R15: 00007ffed7d36588
 </TASK>

Showing all locks held in the system:
2 locks held by kworker/u8:1/13:
 #0: ffff888019c44138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3251 [inline]
 #0: ffff888019c44138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_scheduled_works+0xa52/0x18c0 kernel/workqueue.c:3359
 #1: ffffc90000127c40 (connector_reaper_work){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3252 [inline]
 #1: ffffc90000127c40 (connector_reaper_work){+.+.}-{0:0}, at: process_scheduled_works+0xa8d/0x18c0 kernel/workqueue.c:3359
3 locks held by ksoftirqd/0/15:
 #0: ffffffff8dc630e0 (local_bh){.+.+}-{1:3}, at: __local_bh_disable_ip+0x3c/0x420 kernel/softirq.c:163
 #1: ffffffff8ddcb980 (rcu_read_lock){....}-{1:3}, at: __local_bh_disable_ip+0x3c/0x420 kernel/softirq.c:163
 #2: ffff888024ea8458 (&fq->mq_flush_lock){+.+.}-{3:3}, at: spin_lock include/linux/spinlock_rt.h:45 [inline]
 #2: ffff888024ea8458 (&fq->mq_flush_lock){+.+.}-{3:3}, at: flush_end_io+0xc1/0xf30 block/blk-flush.c:212
1 lock held by khungtaskd/38:
 #0: ffffffff8ddcb980 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:312 [inline]
 #0: ffffffff8ddcb980 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:850 [inline]
 #0: ffffffff8ddcb980 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x2e/0x180 kernel/locking/lockdep.c:6775
3 locks held by kworker/u8:6/750:
1 lock held by udevd/5161:
 #0: ffff8880394dea08 (&ep->lock){+.+.}-{3:3}, at: spin_lock_irq include/linux/spinlock_rt.h:96 [inline]
 #0: ffff8880394dea08 (&ep->lock){+.+.}-{3:3}, at: ep_poll fs/eventpoll.c:2040 [inline]
 #0: ffff8880394dea08 (&ep->lock){+.+.}-{3:3}, at: do_epoll_wait+0x851/0xbd0 fs/eventpoll.c:2462
2 locks held by getty/5547:
 #0: ffff88823be140a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:243
 #1: ffffc90003e8b2e0 (&ldata->atomic_read_lock){+.+.}-{4:4}, at: n_tty_read+0x462/0x13c0 drivers/tty/n_tty.c:2211
2 locks held by syz-executor/5799:
2 locks held by kworker/1:8/5898:
3 locks held by syz-executor/8200:
7 locks held by udevd/8552:
2 locks held by udevd/8651:
1 lock held by syz.4.366/8888:
 #0: ffff88804096c0d0 (&type->s_umount_key#62){++++}-{4:4}, at: __super_lock fs/super.c:60 [inline]
 #0: ffff88804096c0d0 (&type->s_umount_key#62){++++}-{4:4}, at: super_lock+0x2d6/0x3d0 fs/super.c:122
1 lock held by syz.2.421/9286:
 #0: ffff88804096c0d0 (&type->s_umount_key#62){++++}-{4:4}, at: __super_lock fs/super.c:60 [inline]
 #0: ffff88804096c0d0 (&type->s_umount_key#62){++++}-{4:4}, at: super_lock+0x2d6/0x3d0 fs/super.c:122
2 locks held by udevd/10058:
7 locks held by syz.6.632/11197:
1 lock held by syz.6.632/11242:
 #0: ffff8880307c0860 (&fc->uapi_mutex){+.+.}-{4:4}, at: __do_sys_fsconfig fs/fsopen.c:461 [inline]
 #0: ffff8880307c0860 (&fc->uapi_mutex){+.+.}-{4:4}, at: __se_sys_fsconfig+0x6a3/0x820 fs/fsopen.c:350
2 locks held by syz.8.637/11224:
1 lock held by udevadm/11248:
1 lock held by syz.1.639/11250:

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

NMI backtrace for cpu 0
CPU: 0 UID: 0 PID: 38 Comm: khungtaskd Not tainted syzkaller #0 PREEMPT_{RT,(full)} 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026
Call Trace:
 <TASK>
 dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120
 nmi_cpu_backtrace+0x274/0x2d0 lib/nmi_backtrace.c:113
 nmi_trigger_cpumask_backtrace+0x17a/0x300 lib/nmi_backtrace.c:62
 trigger_all_cpu_backtrace include/linux/nmi.h:161 [inline]
 __sys_info lib/sys_info.c:157 [inline]
 sys_info+0x135/0x170 lib/sys_info.c:165
 check_hung_uninterruptible_tasks kernel/hung_task.c:346 [inline]
 watchdog+0xfd9/0x1030 kernel/hung_task.c:515
 kthread+0x388/0x470 kernel/kthread.c:436
 ret_from_fork+0x51e/0xb90 arch/x86/kernel/process.c:158
 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: 5799 Comm: syz-executor Not tainted syzkaller #0 PREEMPT_{RT,(full)} 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026
RIP: 0010:unwind_next_frame+0x18dd/0x23c0 arch/x86/kernel/unwind_orc.c:679
Code: 49 0f bf 04 24 48 01 c6 4c 89 f7 48 89 da e8 9a 0d 00 00 84 c0 0f 84 46 01 00 00 48 bd 00 00 00 00 00 fc ff df 48 8b 44 24 20 <0f> b6 04 28 84 c0 0f 85 16 08 00 00 b3 01 8b 84 24 8c 00 00 00 41
RSP: 0018:ffffc90004597418 EFLAGS: 00000202
RAX: 1ffff920008b2e9d RBX: ffffffff9006dda4 RCX: 0000000000000001
RDX: ffffc90004597528 RSI: dffffc0000000000 RDI: ffffc90004597b08
RBP: dffffc0000000000 R08: ffffc90004597b08 R09: 0000000000000000
R10: ffffc90004597538 R11: fffff520008b2ea9 R12: ffffc90004597538
R13: 1ffff920008b2e9f R14: ffffc900045974e8 R15: 1ffffffff200dbb4
FS:  0000555588ae0500(0000) GS:ffff88812643c000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fe4b6d49000 CR3: 000000005b552000 CR4: 00000000003526f0
Call Trace:
 <TASK>
 arch_stack_walk+0x11b/0x150 arch/x86/kernel/stacktrace.c:25
 stack_trace_save+0xa9/0x100 kernel/stacktrace.c:122
 kasan_save_stack mm/kasan/common.c:57 [inline]
 kasan_save_track+0x3e/0x80 mm/kasan/common.c:78
 kasan_save_free_info+0x46/0x50 mm/kasan/generic.c:584
 poison_slab_object mm/kasan/common.c:253 [inline]
 __kasan_slab_free+0x5c/0x80 mm/kasan/common.c:285
 kasan_slab_free include/linux/kasan.h:235 [inline]
 slab_free_hook mm/slub.c:2685 [inline]
 slab_free mm/slub.c:6165 [inline]
 kmem_cache_free+0x185/0x6b0 mm/slub.c:6295
 xfs_trans_alloc+0x49c/0x9b0 fs/xfs/xfs_trans.c:-1
 xfs_vn_sync_lazytime+0xaf/0x150 fs/xfs/xfs_iops.c:1238
 sync_lazytime+0x12d/0x2d0 fs/fs-writeback.c:1721
 iput+0x230/0xe80 fs/inode.c:1997
 __dentry_kill+0x1a2/0x5e0 fs/dcache.c:670
 shrink_kill+0xa9/0x2c0 fs/dcache.c:1147
 shrink_dentry_list+0x2e3/0x5e0 fs/dcache.c:1174
 shrink_dcache_tree+0xcf/0x310 fs/dcache.c:-1
 do_one_tree fs/dcache.c:1654 [inline]
 shrink_dcache_for_umount+0xa8/0x1f0 fs/dcache.c:1671
 generic_shutdown_super+0x6f/0x2d0 fs/super.c:624
 kill_block_super+0x44/0x90 fs/super.c:1725
 xfs_kill_sb+0x15/0x50 fs/xfs/xfs_super.c:2284
 deactivate_locked_super+0xbc/0x130 fs/super.c:476
 cleanup_mnt+0x437/0x4d0 fs/namespace.c:1312
 task_work_run+0x1d9/0x270 kernel/task_work.c:233
 resume_user_mode_work include/linux/resume_user_mode.h:50 [inline]
 __exit_to_user_mode_loop kernel/entry/common.c:67 [inline]
 exit_to_user_mode_loop+0xed/0x480 kernel/entry/common.c:98
 __exit_to_user_mode_prepare include/linux/irq-entry-common.h:226 [inline]
 syscall_exit_to_user_mode_prepare include/linux/irq-entry-common.h:256 [inline]
 syscall_exit_to_user_mode include/linux/entry-common.h:325 [inline]
 do_syscall_64+0x32d/0xf80 arch/x86/entry/syscall_64.c:100
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f46fa8ed9d7
Code: a2 c7 05 1c fd 24 00 00 00 00 00 eb 96 e8 e1 12 00 00 90 31 f6 e9 09 00 00 00 66 0f 1f 84 00 00 00 00 00 b8 a6 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 01 c3 48 c7 c2 e8 ff ff ff f7 d8 64 89 02 b8
RSP: 002b:00007ffc1217a1f8 EFLAGS: 00000246 ORIG_RAX: 00000000000000a6
RAX: 0000000000000000 RBX: 00007f46fa982050 RCX: 00007f46fa8ed9d7
RDX: 0000000000000000 RSI: 0000000000000009 RDI: 00007ffc1217a2b0
RBP: 00007ffc1217a2b0 R08: 00007ffc1217b2b0 R09: 00000000ffffffff
R10: 0000000000000000 R11: 0000000000000246 R12: 00007ffc1217b340
R13: 00007f46fa982050 R14: 00000000000212a0 R15: 00007ffc1217b380
 </TASK>