syzbot

INFO: task syz.1.386:8876 blocked for more than 143 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.1.386       state:D stack:26208 pid:8876  tgid:8875  ppid:8391   task_flags:0x400040 flags:0x00080002
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5295 [inline]
 __schedule+0x1553/0x5240 kernel/sched/core.c:6908
 __schedule_loop kernel/sched/core.c:6990 [inline]
 rt_mutex_schedule+0x76/0xf0 kernel/sched/core.c:7286
 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: 0033:0x7f945988c799
RSP: 002b:00007f9457ae6028 EFLAGS: 00000246 ORIG_RAX: 00000000000000b3
RAX: ffffffffffffffda RBX: 00007f9459b05fa0 RCX: 00007f945988c799
RDX: 0000000000000000 RSI: 0000200000000000 RDI: ffffffff80000801
RBP: 00007f9459922c99 R08: 0000000000000000 R09: 0000000000000000
R10: 0000200000000280 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f9459b06038 R14: 00007f9459b05fa0 R15: 00007ffff0c7d308
 </TASK>

Showing all locks held in the system:
1 lock held by khungtaskd/37:
 #0: ffffffff8ddcb880 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:312 [inline]
 #0: ffffffff8ddcb880 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:850 [inline]
 #0: ffffffff8ddcb880 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x2e/0x180 kernel/locking/lockdep.c:6775
2 locks held by getty/5552:
 #0: ffff8880373200a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:243
 #1: ffffc90003e832e0 (&ldata->atomic_read_lock){+.+.}-{4:4}, at: n_tty_read+0x462/0x13c0 drivers/tty/n_tty.c:2211
2 locks held by syz-executor/5795:
3 locks held by udevd/5856:
 #0: ffff888022795528 (&sb->s_type->i_mutex_key#9){++++}-{4:4}, at: inode_lock_shared include/linux/fs.h:1043 [inline]
 #0: ffff888022795528 (&sb->s_type->i_mutex_key#9){++++}-{4:4}, at: blkdev_read_iter+0x2ff/0x440 block/fops.c:854
 #1: ffff8880227956f8 (mapping.invalidate_lock){++++}-{4:4}, at: filemap_invalidate_lock_shared include/linux/fs.h:1093 [inline]
 #1: ffff8880227956f8 (mapping.invalidate_lock){++++}-{4:4}, at: do_page_cache_ra mm/readahead.c:333 [inline]
 #1: ffff8880227956f8 (mapping.invalidate_lock){++++}-{4:4}, at: force_page_cache_ra+0x263/0x2e0 mm/readahead.c:364
 #2: ffff888022795660 (&xa->xa_lock#10){+.+.}-{3:3}, at: spin_lock_irq include/linux/spinlock_rt.h:96 [inline]
 #2: ffff888022795660 (&xa->xa_lock#10){+.+.}-{3:3}, at: __filemap_add_folio+0x981/0x1220 mm/filemap.c:875
1 lock held by syz.1.386/8876:
 #0: ffff88802b26a0d0 (&type->s_umount_key#62){++++}-{4:4}, at: __super_lock fs/super.c:60 [inline]
 #0: ffff88802b26a0d0 (&type->s_umount_key#62){++++}-{4:4}, at: super_lock+0x2d6/0x3d0 fs/super.c:122
1 lock held by syz.0.367/9371:
 #0: ffff88802b26a0d0 (&type->s_umount_key#62){++++}-{4:4}, at: __super_lock fs/super.c:60 [inline]
 #0: ffff88802b26a0d0 (&type->s_umount_key#62){++++}-{4:4}, at: super_lock+0x2d6/0x3d0 fs/super.c:122
1 lock held by syz.5.505/10105:
 #0: ffff88802b26a0d0 (&type->s_umount_key#62){++++}-{4:4}, at: __super_lock fs/super.c:60 [inline]
 #0: ffff88802b26a0d0 (&type->s_umount_key#62){++++}-{4:4}, at: super_lock+0x2d6/0x3d0 fs/super.c:122
1 lock held by syz.1.577/11064:
2 locks held by syz.6.581/11082:
 #0: ffffffff8e3d86f8 (uuid_mutex){+.+.}-{4:4}, at: btrfs_get_tree_super fs/btrfs/super.c:1852 [inline]
 #0: ffffffff8e3d86f8 (uuid_mutex){+.+.}-{4:4}, at: btrfs_get_tree_subvol fs/btrfs/super.c:2087 [inline]
 #0: ffffffff8e3d86f8 (uuid_mutex){+.+.}-{4:4}, at: btrfs_get_tree+0x47c/0x1930 fs/btrfs/super.c:2121
 #1: ffff8880225fca38 (mapping.invalidate_lock){++++}-{4:4}, at: filemap_invalidate_lock include/linux/fs.h:1083 [inline]
 #1: ffff8880225fca38 (mapping.invalidate_lock){++++}-{4:4}, at: btrfs_read_disk_super+0x1fd/0x530 fs/btrfs/volumes.c:1371
4 locks held by syz.2.582/11094:
2 locks held by syz.3.574/11096:
1 lock held by syz.9.583/11103:
1 lock held by sed/11106:

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

NMI backtrace for cpu 1
CPU: 1 UID: 0 PID: 37 Comm: khungtaskd Not tainted syzkaller #0 PREEMPT_{RT,(full)} 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/27/2026
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 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 UID: 0 PID: 16 Comm: ktimers/0 Not tainted syzkaller #0 PREEMPT_{RT,(full)} 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/27/2026
RIP: 0010:lock_release+0xd/0x3d0 kernel/locking/lockdep.c:5876
Code: 00 00 00 e9 0e ff ff ff 0f 1f 44 00 00 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 f3 0f 1e fa 55 41 57 41 56 41 55 41 54 <53> 48 83 ec 30 49 89 f5 49 89 fe 65 48 8b 05 90 fb ad 10 48 89 44
RSP: 0018:ffffc90000157ab0 EFLAGS: 00000096
RAX: 0000000000000000 RBX: 0000000000000082 RCX: 0000000000000002
RDX: 0000000000000001 RSI: ffffffff81b09cf3 RDI: ffffffff998d7e50
RBP: ffffc90000157cb8 R08: 0000000000000003 R09: 0000000000000004
R10: dffffc0000000000 R11: fffff5200002af40 R12: dffffc0000000000
R13: ffff8880256b4710 R14: ffffffff998d7e38 R15: ffffc90000157c00
FS:  0000000000000000(0000) GS:ffff88812633c000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f7f29425900 CR3: 000000004dbc6000 CR4: 00000000003526f0
Call Trace:
 <TASK>
 __raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:176 [inline]
 _raw_spin_unlock_irqrestore+0x1b/0x80 kernel/locking/spinlock.c:194
 debug_timer_deactivate kernel/time/timer.c:798 [inline]
 debug_deactivate kernel/time/timer.c:842 [inline]
 detach_timer+0x33/0x300 kernel/time/timer.c:889
 expire_timers kernel/time/timer.c:1782 [inline]
 __run_timers kernel/time/timer.c:2373 [inline]
 __run_timer_base+0x624/0x9f0 kernel/time/timer.c:2385
 run_timer_base kernel/time/timer.c:2394 [inline]
 run_timer_softirq+0xb7/0x170 kernel/time/timer.c:2404
 handle_softirqs+0x1de/0x6f0 kernel/softirq.c:622
 __do_softirq kernel/softirq.c:656 [inline]
 run_ktimerd+0x69/0x100 kernel/softirq.c:1138
 smpboot_thread_fn+0x541/0xa50 kernel/smpboot.c:160
 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>