syzbot

INFO: task syz.0.17:4439 blocked for more than 143 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.0.17        state:D stack:28464 pid:4439  ppid:4385   flags:0x00004004
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5244 [inline]
 __schedule+0x10ec/0x40b0 kernel/sched/core.c:6561
 schedule+0xb9/0x180 kernel/sched/core.c:6637
 schedule_preempt_disabled+0xf/0x20 kernel/sched/core.c:6696
 rwsem_down_read_slowpath+0x4f4/0x840 kernel/locking/rwsem.c:1094
 __down_read_common kernel/locking/rwsem.c:1261 [inline]
 __down_read kernel/locking/rwsem.c:1274 [inline]
 down_read+0x94/0x2d0 kernel/locking/rwsem.c:1522
 iterate_supers+0xa4/0x1d0 fs/super.c:755
 ksys_sync+0x91/0x150 fs/sync.c:102
 __ia32_sys_sync+0xa/0x10 fs/sync.c:113
 do_syscall_x64 arch/x86/entry/common.c:51 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:81
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7fef47b8eba9
RSP: 002b:00007fef4897b038 EFLAGS: 00000246 ORIG_RAX: 00000000000000a2
RAX: ffffffffffffffda RBX: 00007fef47dd6090 RCX: 00007fef47b8eba9
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 00007fef47dd6090 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fef47dd6128 R14: 00007fef47dd6090 R15: 00007ffe8759f248
 </TASK>

Showing all locks held in the system:
1 lock held by rcu_tasks_kthre/12:
 #0: ffffffff8cb2b570 (rcu_tasks.tasks_gp_mutex){+.+.}-{3:3}, at: rcu_tasks_one_gp+0x33/0xf00 kernel/rcu/tasks.h:517
1 lock held by rcu_tasks_trace/13:
 #0: ffffffff8cb2bd90 (rcu_tasks_trace.tasks_gp_mutex){+.+.}-{3:3}, at: rcu_tasks_one_gp+0x33/0xf00 kernel/rcu/tasks.h:517
1 lock held by khungtaskd/27:
 #0: ffffffff8cb2abe0 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:350 [inline]
 #0: ffffffff8cb2abe0 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:791 [inline]
 #0: ffffffff8cb2abe0 (rcu_read_lock){....}-{1:2}, at: debug_show_all_locks+0x51/0x290 kernel/locking/lockdep.c:6513
2 locks held by getty/4026:
 #0: ffff88802ff21098 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x21/0x70 drivers/tty/tty_ldisc.c:244
 #1: ffffc9000327b2f0 (&ldata->atomic_read_lock){+.+.}-{3:3}, at: n_tty_read+0x41b/0x1380 drivers/tty/n_tty.c:2198
1 lock held by syz.0.17/4438:
 #0: ffff88807ece80e0 (&type->s_umount_key#52/1){+.+.}-{3:3}, at: alloc_super+0x1fa/0x930 fs/super.c:228
1 lock held by syz.0.17/4439:
 #0: ffff88807ece80e0 (&type->s_umount_key#71){.+.+}-{3:3}, at: iterate_supers+0xa4/0x1d0 fs/super.c:755
1 lock held by syz.1.18/4467:
 #0: ffff88801f25e0e0 (&type->s_umount_key#52/1){+.+.}-{3:3}, at: alloc_super+0x1fa/0x930 fs/super.c:228
1 lock held by syz.1.18/4468:
 #0: ffff88807ece80e0 (&type->s_umount_key#71){.+.+}-{3:3}, at: iterate_supers+0xa4/0x1d0 fs/super.c:755
1 lock held by syz.2.19/4490:
 #0: ffff888077f840e0 (&type->s_umount_key#52/1){+.+.}-{3:3}, at: alloc_super+0x1fa/0x930 fs/super.c:228
1 lock held by syz.2.19/4491:
 #0: ffff88807ece80e0 (&type->s_umount_key#71){.+.+}-{3:3}, at: iterate_supers+0xa4/0x1d0 fs/super.c:755
1 lock held by syz.3.20/4514:
 #0: ffff88805efb20e0 (&type->s_umount_key#52/1){+.+.}-{3:3}, at: alloc_super+0x1fa/0x930 fs/super.c:228
1 lock held by syz.3.20/4515:
 #0: ffff88807ece80e0 (&type->s_umount_key#71){.+.+}-{3:3}, at: iterate_supers+0xa4/0x1d0 fs/super.c:755
1 lock held by syz.4.21/4543:
 #0: ffff88807d6b80e0 (&type->s_umount_key#52/1){+.+.}-{3:3}, at: alloc_super+0x1fa/0x930 fs/super.c:228
1 lock held by syz.4.21/4544:
 #0: ffff88807ece80e0 (&type->s_umount_key#71){.+.+}-{3:3}, at: iterate_supers+0xa4/0x1d0 fs/super.c:755
1 lock held by syz.5.22/4578:
 #0: ffff88805a5fa0e0 (&type->s_umount_key#52/1){+.+.}-{3:3}, at: alloc_super+0x1fa/0x930 fs/super.c:228
1 lock held by syz.5.22/4579:
 #0: ffff88807ece80e0 (&type->s_umount_key#71){.+.+}-{3:3}, at: iterate_supers+0xa4/0x1d0 fs/super.c:755
1 lock held by syz.6.23/4607:
 #0: ffff8880772440e0 (&type->s_umount_key#52/1){+.+.}-{3:3}, at: alloc_super+0x1fa/0x930 fs/super.c:228
1 lock held by syz.6.23/4608:
 #0: ffff88807ece80e0 (&type->s_umount_key#71){.+.+}-{3:3}, at: iterate_supers+0xa4/0x1d0 fs/super.c:755
1 lock held by syz.7.24/4635:
 #0: ffff8880241840e0 (&type->s_umount_key#52/1){+.+.}-{3:3}, at: alloc_super+0x1fa/0x930 fs/super.c:228
1 lock held by syz.7.24/4637:
 #0: ffff88807ece80e0 (&type->s_umount_key#71){.+.+}-{3:3}, at: iterate_supers+0xa4/0x1d0 fs/super.c:755
1 lock held by syz.8.25/4665:
 #0: ffff888058bfa0e0 (&type->s_umount_key#52/1){+.+.}-{3:3}, at: alloc_super+0x1fa/0x930 fs/super.c:228
1 lock held by syz.8.25/4667:
 #0: ffff88807ece80e0 (&type->s_umount_key#71){.+.+}-{3:3}, at: iterate_supers+0xa4/0x1d0 fs/super.c:755

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

NMI backtrace for cpu 0
CPU: 0 PID: 27 Comm: khungtaskd Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/18/2025
Call Trace:
 <TASK>
 dump_stack_lvl+0x168/0x22e lib/dump_stack.c:106
 nmi_cpu_backtrace+0x3f4/0x470 lib/nmi_backtrace.c:111
 nmi_trigger_cpumask_backtrace+0x1d4/0x450 lib/nmi_backtrace.c:62
 trigger_all_cpu_backtrace include/linux/nmi.h:148 [inline]
 check_hung_uninterruptible_tasks kernel/hung_task.c:220 [inline]
 watchdog+0xeee/0xf30 kernel/hung_task.c:377
 kthread+0x29d/0x330 kernel/kthread.c:376
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295
 </TASK>
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 PID: 3619 Comm: syslogd Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/18/2025
RIP: 0010:get_current arch/x86/include/asm/current.h:15 [inline]
RIP: 0010:__sanitizer_cov_trace_pc+0x4/0x60 kernel/kcov.c:215
Code: 00 00 00 00 00 90 53 48 89 fb e8 17 00 00 00 48 8b 3d d0 a6 9e 0c 48 89 de 5b e9 37 58 4f 00 00 00 cc cc 00 00 cc 48 8b 04 24 <65> 48 8b 0d a4 9e 81 7e 65 8b 15 a5 9e 81 7e 81 e2 00 01 ff 00 74
RSP: 0018:ffffc90003087e18 EFLAGS: 00000246
RAX: ffffffff81e69d84 RBX: ffff88807d5d9b80 RCX: 0000000000000000
RDX: ffff88807efa3b80 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 0000000000000000 R08: dffffc0000000000 R09: ffffed1004a611e1
R10: ffffed1004a611e1 R11: 1ffff11004a611e0 R12: dffffc0000000000
R13: 1ffff1100fdf488f R14: ffff88807d5d9b80 R15: ffff88807d5d9bfc
FS:  00007f78ceda7c80(0000) GS:ffff8880b8f00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000556174549a38 CR3: 000000007e4d2000 CR4: 00000000003506e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 file_needs_f_pos_lock fs/file.c:1027 [inline]
 __fdget_pos+0x1d4/0x360 fs/file.c:1036
 fdget_pos include/linux/file.h:74 [inline]
 ksys_read+0x78/0x240 fs/read_write.c:604
 do_syscall_x64 arch/x86/entry/common.c:51 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:81
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f78ceef7407
Code: 48 89 fa 4c 89 df e8 38 aa 00 00 8b 93 08 03 00 00 59 5e 48 83 f8 fc 74 1a 5b c3 0f 1f 84 00 00 00 00 00 48 8b 44 24 10 0f 05 <5b> c3 0f 1f 80 00 00 00 00 83 e2 39 83 fa 08 75 de e8 23 ff ff ff
RSP: 002b:00007ffcaa342730 EFLAGS: 00000202 ORIG_RAX: 0000000000000000
RAX: ffffffffffffffda RBX: 00007f78ceda7c80 RCX: 00007f78ceef7407
RDX: 00000000000000ff RSI: 000055729254d950 RDI: 0000000000000000
RBP: 000055729254d910 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000202 R12: 000055729254d9a3
R13: 0000000000000000 R14: 000055729254d950 R15: 0000557263d04d98
 </TASK>