syzbot

INFO: task syz.1.18:5940 blocked for more than 143 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.1.18        state:D stack:27864 pid:5940  tgid:5940  ppid:5769   task_flags:0x400040 flags:0x00080002
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5504 [inline]
 __schedule+0x16dc/0x5500 kernel/sched/core.c:7228
 __schedule_loop kernel/sched/core.c:7307 [inline]
 rt_mutex_schedule+0x76/0xf0 kernel/sched/core.c:7603
 rt_mutex_slowlock_block kernel/locking/rtmutex.c:1670 [inline]
 __rt_mutex_slowlock kernel/locking/rtmutex.c:1747 [inline]
 __rt_mutex_slowlock_locked+0x1f84/0x25b0 kernel/locking/rtmutex.c:1787
 rt_mutex_slowlock+0xbd/0x170 kernel/locking/rtmutex.c:1827
 __rt_mutex_lock kernel/locking/rtmutex.c:1842 [inline]
 rwbase_write_lock+0x14c/0x720 kernel/locking/rwbase_rt.c:251
 inode_lock include/linux/fs.h:1029 [inline]
 blkdev_fallocate+0x263/0x550 block/fops.c:907
 vfs_fallocate+0x663/0x7f0 fs/open.c:338
 ksys_fallocate fs/open.c:362 [inline]
 __do_sys_fallocate fs/open.c:367 [inline]
 __se_sys_fallocate fs/open.c:365 [inline]
 __x64_sys_fallocate+0xbf/0x110 fs/open.c:365
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x174/0x580 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7ff2f04fce59
RSP: 002b:00007fffc0cd3c58 EFLAGS: 00000246 ORIG_RAX: 000000000000011d
RAX: ffffffffffffffda RBX: 00007ff2f0775fa0 RCX: 00007ff2f04fce59
RDX: 0000000000000600 RSI: 0000000000000011 RDI: 0000000000000003
RBP: 00007ff2f0592d6f R08: 0000000000000000 R09: 0000000000000000
R10: 001800000007c000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007ff2f0775fac R14: 00007ff2f0775fa0 R15: 00007ff2f0775fa0
 </TASK>
INFO: task syz.3.20:5941 blocked for more than 143 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.3.20        state:D stack:27864 pid:5941  tgid:5941  ppid:5772   task_flags:0x400040 flags:0x00080002
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5504 [inline]
 __schedule+0x16dc/0x5500 kernel/sched/core.c:7228
 __schedule_loop kernel/sched/core.c:7307 [inline]
 rt_mutex_schedule+0x76/0xf0 kernel/sched/core.c:7603
 rt_mutex_slowlock_block kernel/locking/rtmutex.c:1670 [inline]
 __rt_mutex_slowlock kernel/locking/rtmutex.c:1747 [inline]
 __rt_mutex_slowlock_locked+0x1f84/0x25b0 kernel/locking/rtmutex.c:1787
 rt_mutex_slowlock+0xbd/0x170 kernel/locking/rtmutex.c:1827
 __rt_mutex_lock kernel/locking/rtmutex.c:1842 [inline]
 rwbase_write_lock+0x14c/0x720 kernel/locking/rwbase_rt.c:251
 inode_lock include/linux/fs.h:1029 [inline]
 blkdev_fallocate+0x263/0x550 block/fops.c:907
 vfs_fallocate+0x663/0x7f0 fs/open.c:338
 ksys_fallocate fs/open.c:362 [inline]
 __do_sys_fallocate fs/open.c:367 [inline]
 __se_sys_fallocate fs/open.c:365 [inline]
 __x64_sys_fallocate+0xbf/0x110 fs/open.c:365
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x174/0x580 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f0d8d9cce59
RSP: 002b:00007ffd3c4ebee8 EFLAGS: 00000246 ORIG_RAX: 000000000000011d
RAX: ffffffffffffffda RBX: 00007f0d8dc45fa0 RCX: 00007f0d8d9cce59
RDX: 0000000000000600 RSI: 0000000000000011 RDI: 0000000000000003
RBP: 00007f0d8da62d6f R08: 0000000000000000 R09: 0000000000000000
R10: 001800000007c000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f0d8dc45fac R14: 00007f0d8dc45fa0 R15: 00007f0d8dc45fa0
 </TASK>
INFO: task syz.0.17:5942 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:27864 pid:5942  tgid:5942  ppid:5761   task_flags:0x400040 flags:0x00080002
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5504 [inline]
 __schedule+0x16dc/0x5500 kernel/sched/core.c:7228
 __schedule_loop kernel/sched/core.c:7307 [inline]
 rt_mutex_schedule+0x76/0xf0 kernel/sched/core.c:7603
 rt_mutex_slowlock_block kernel/locking/rtmutex.c:1670 [inline]
 __rt_mutex_slowlock kernel/locking/rtmutex.c:1747 [inline]
 __rt_mutex_slowlock_locked+0x1f84/0x25b0 kernel/locking/rtmutex.c:1787
 rt_mutex_slowlock+0xbd/0x170 kernel/locking/rtmutex.c:1827
 __rt_mutex_lock kernel/locking/rtmutex.c:1842 [inline]
 rwbase_write_lock+0x14c/0x720 kernel/locking/rwbase_rt.c:251
 inode_lock include/linux/fs.h:1029 [inline]
 blkdev_fallocate+0x263/0x550 block/fops.c:907
 vfs_fallocate+0x663/0x7f0 fs/open.c:338
 ksys_fallocate fs/open.c:362 [inline]
 __do_sys_fallocate fs/open.c:367 [inline]
 __se_sys_fallocate fs/open.c:365 [inline]
 __x64_sys_fallocate+0xbf/0x110 fs/open.c:365
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x174/0x580 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fa5d160ce59
RSP: 002b:00007ffe3583fb28 EFLAGS: 00000246 ORIG_RAX: 000000000000011d
RAX: ffffffffffffffda RBX: 00007fa5d1885fa0 RCX: 00007fa5d160ce59
RDX: 0000000000000600 RSI: 0000000000000011 RDI: 0000000000000003
RBP: 00007fa5d16a2d6f R08: 0000000000000000 R09: 0000000000000000
R10: 001800000007c000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fa5d1885fac R14: 00007fa5d1885fa0 R15: 00007fa5d1885fa0
 </TASK>
INFO: task syz.4.21:5944 blocked for more than 143 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.4.21        state:D stack:27768 pid:5944  tgid:5944  ppid:5775   task_flags:0x400040 flags:0x00080002
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5504 [inline]
 __schedule+0x16dc/0x5500 kernel/sched/core.c:7228
 __schedule_loop kernel/sched/core.c:7307 [inline]
 rt_mutex_schedule+0x76/0xf0 kernel/sched/core.c:7603
 rt_mutex_slowlock_block kernel/locking/rtmutex.c:1670 [inline]
 __rt_mutex_slowlock kernel/locking/rtmutex.c:1747 [inline]
 __rt_mutex_slowlock_locked+0x1f84/0x25b0 kernel/locking/rtmutex.c:1787
 rt_mutex_slowlock+0xbd/0x170 kernel/locking/rtmutex.c:1827
 __rt_mutex_lock kernel/locking/rtmutex.c:1842 [inline]
 rwbase_write_lock+0x14c/0x720 kernel/locking/rwbase_rt.c:251
 inode_lock include/linux/fs.h:1029 [inline]
 blkdev_fallocate+0x263/0x550 block/fops.c:907
 vfs_fallocate+0x663/0x7f0 fs/open.c:338
 ksys_fallocate fs/open.c:362 [inline]
 __do_sys_fallocate fs/open.c:367 [inline]
 __se_sys_fallocate fs/open.c:365 [inline]
 __x64_sys_fallocate+0xbf/0x110 fs/open.c:365
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x174/0x580 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f78c0f5ce59
RSP: 002b:00007ffc7d020ac8 EFLAGS: 00000246 ORIG_RAX: 000000000000011d
RAX: ffffffffffffffda RBX: 00007f78c11d5fa0 RCX: 00007f78c0f5ce59
RDX: 0000000000000600 RSI: 0000000000000011 RDI: 0000000000000003
RBP: 00007f78c0ff2d6f R08: 0000000000000000 R09: 0000000000000000
R10: 001800000007c000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f78c11d5fac R14: 00007f78c11d5fa0 R15: 00007f78c11d5fa0
 </TASK>
INFO: lockdep is turned off.
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 05/09/2026
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:162 [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:353 [inline]
 watchdog+0xfd7/0x1030 kernel/hung_task.c:561
 kthread+0x388/0x470 kernel/kthread.c:436
 ret_from_fork+0x514/0xb70 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: 17 Comm: pr/legacy Not tainted syzkaller #0 PREEMPT_{RT,(full)} 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/09/2026
RIP: 0010:preempt_latency_start kernel/sched/core.c:5959 [inline]
RIP: 0010:preempt_count_add+0xb9/0x190 kernel/sched/core.c:5982
Code: 0d 00 85 c0 74 09 31 db 31 ff e8 52 af 0d 00 65 4c 8b 35 a2 af b5 10 49 81 c6 e8 15 00 00 4c 89 f0 48 c1 e8 03 42 80 3c 38 00 <74> 08 4c 89 f7 e8 bd ac 98 00 49 89 1e 5b 41 5e 41 5f e9 10 6c 88
RSP: 0018:ffffc900001679e8 EFLAGS: 00000246
RAX: 1ffff1100395ae5d RBX: ffffffff8b169a35 RCX: ffffffff99544500
RDX: 000000000000009e RSI: ffffffff8b877e00 RDI: ffffffff8b169a35
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
R10: dffffc0000000000 R11: ffffffff8b1699d0 R12: 1ffffffff331f9aa
R13: 00000000ffffffff R14: ffff88801cad72e8 R15: dffffc0000000000
FS:  0000000000000000(0000) GS:ffff888126390000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000055887a3afde0 CR3: 00000000341d6000 CR4: 00000000003526f0
Call Trace:
 <TASK>
 delay_tsc+0x65/0xc0 arch/x86/lib/delay.c:79
 udelay include/asm-generic/delay.h:62 [inline]
 wait_for_lsr+0x14d/0x300 drivers/tty/serial/8250/8250_port.c:1979
 serial8250_fifo_wait_for_lsr_thre drivers/tty/serial/8250/8250_port.c:3210 [inline]
 serial8250_console_fifo_write drivers/tty/serial/8250/8250_port.c:3275 [inline]
 serial8250_console_write+0x1232/0x1bd0 drivers/tty/serial/8250/8250_port.c:3360
 console_emit_next_record kernel/printk/printk.c:3163 [inline]
 console_flush_one_record+0x642/0xb50 kernel/printk/printk.c:3269
 legacy_kthread_func+0x1b6/0x250 kernel/printk/printk.c:3712
 kthread+0x388/0x470 kernel/kthread.c:436
 ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>