[syzbot] [io-uring?] INFO: task hung in io_wq_put_and_exit (6)

[syzbot <syzbot+4eb282331cab6d5b6588@syzkaller.appspotmail.com>]

Hello,

syzbot found the following issue on:

HEAD commit:    931e46dcbc7e Add linux-next specific files for 20250814
git tree:       linux-next
console+strace: https://syzkaller.appspot.com/x/log.txt?x=16d26ba2580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=a286bd75352e92fa
dashboard link: https://syzkaller.appspot.com/bug?extid=4eb282331cab6d5b6588
compiler:       Debian clang version 20.1.7 (++20250616065708+6146a88f6049-1~exp1~20250616065826.132), Debian LLD 20.1.7
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=13d206f0580000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=13e993a2580000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/fb896162d550/disk-931e46dc.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/45f6f857b82c/vmlinux-931e46dc.xz
kernel image: https://storage.googleapis.com/syzbot-assets/0f16e70143e1/bzImage-931e46dc.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+4eb282331cab6d5b6588@syzkaller.appspotmail.com

INFO: task syz-executor369:6499 blocked for more than 143 seconds.
      Not tainted 6.17.0-rc1-next-20250814-syzkaller #0
      Blocked by coredump.
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz-executor369 state:D stack:27984 pid:6499  tgid:6498  ppid:5865   task_flags:0x400548 flags:0x00024002
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5357 [inline]
 __schedule+0x1798/0x4cc0 kernel/sched/core.c:6961
 __schedule_loop kernel/sched/core.c:7043 [inline]
 schedule+0x165/0x360 kernel/sched/core.c:7058
 schedule_timeout+0x9a/0x270 kernel/time/sleep_timeout.c:75
 do_wait_for_common kernel/sched/completion.c:100 [inline]
 __wait_for_common kernel/sched/completion.c:121 [inline]
 wait_for_common kernel/sched/completion.c:132 [inline]
 wait_for_completion+0x2bf/0x5d0 kernel/sched/completion.c:153
 io_wq_exit_workers io_uring/io-wq.c:1327 [inline]
 io_wq_put_and_exit+0x316/0x650 io_uring/io-wq.c:1355
 io_uring_clean_tctx+0x11f/0x1a0 io_uring/tctx.c:203
 io_uring_cancel_generic+0x6ca/0x7d0 io_uring/io_uring.c:3272
 io_uring_files_cancel include/linux/io_uring.h:19 [inline]
 do_exit+0x345/0x2300 kernel/exit.c:907
 do_group_exit+0x21c/0x2d0 kernel/exit.c:1102
 get_signal+0x1286/0x1340 kernel/signal.c:3034
 arch_do_signal_or_restart+0x9a/0x750 arch/x86/kernel/signal.c:337
 exit_to_user_mode_loop+0x75/0x110 kernel/entry/common.c:40
 exit_to_user_mode_prepare include/linux/irq-entry-common.h:225 [inline]
 syscall_exit_to_user_mode_work include/linux/entry-common.h:175 [inline]
 syscall_exit_to_user_mode include/linux/entry-common.h:210 [inline]
 do_syscall_64+0x2bd/0x3b0 arch/x86/entry/syscall_64.c:100
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fec3779c659
RSP: 002b:00007fec37752218 EFLAGS: 00000246 ORIG_RAX: 00000000000000ca
RAX: fffffffffffffe00 RBX: 00007fec37823328 RCX: 00007fec3779c659
RDX: 0000000000000000 RSI: 0000000000000080 RDI: 00007fec37823328
RBP: 00007fec37823320 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007fec377f0270
R13: 0000000000000000 R14: 0000200000000200 R15: 00007ffd3af7b848
 </TASK>
INFO: lockdep is turned off.
NMI backtrace for cpu 1
CPU: 1 UID: 0 PID: 31 Comm: khungtaskd Not tainted 6.17.0-rc1-next-20250814-syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025
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:160 [inline]
 check_hung_uninterruptible_tasks kernel/hung_task.c:332 [inline]
 watchdog+0xf60/0xfa0 kernel/hung_task.c:495
 kthread+0x711/0x8a0 kernel/kthread.c:463
 ret_from_fork+0x3f9/0x770 arch/x86/kernel/process.c:148
 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: 6811 Comm: iou-wrk-6807 Not tainted 6.17.0-rc1-next-20250814-syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025
RIP: 0010:native_read_msr_safe arch/x86/include/asm/msr.h:121 [inline]
RIP: 0010:__rdmsr_safe_on_cpu+0x3c/0x130 arch/x86/lib/msr-smp.c:156
Code: bd 00 00 00 00 00 fc ff df e8 10 d2 bd fc 48 89 d8 48 c1 e8 03 42 0f b6 04 28 84 c0 0f 85 82 00 00 00 44 8b 23 44 89 e1 0f 32 <31> ed 49 89 c7 49 89 d6 0f 1f 44 00 00 e8 e2 d1 bd fc 49 c1 e6 20
RSP: 0018:ffffc90004e17428 EFLAGS: 00000046
RAX: 0000000000000000 RBX: ffffc90004e17600 RCX: 0000000000000000
RDX: 0000000000000000 RSI: ffffffff8be34be0 RDI: ffffc90004e17600
RBP: ffffc90004e17538 R08: ffffffff8fa3b137 R09: 1ffffffff1f47626
R10: dffffc0000000000 R11: ffffffff8501d3e0 R12: 0000000000000000
R13: dffffc0000000000 R14: ffffffff8501d3e0 R15: 1ffff920009c2eb9
FS:  00007fec377526c0(0000) GS:ffff888125c0f000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000200000a89000 CR3: 0000000026df2000 CR4: 00000000003526f0
Call Trace:
 <TASK>
 csd_do_func kernel/smp.c:136 [inline]
 generic_exec_single+0x237/0x500 kernel/smp.c:439
 smp_call_function_single_async+0x79/0x110 kernel/smp.c:732
 rdmsr_safe_on_cpu+0x127/0x230 arch/x86/lib/msr-smp.c:179
 msr_read+0x14d/0x250 arch/x86/kernel/msr.c:66
 loop_rw_iter+0x425/0x660 include/linux/uio.h:-1
 io_iter_do_read io_uring/rw.c:830 [inline]
 __io_read+0x1326/0x14f0 io_uring/rw.c:941
 io_read+0x1c/0x60 io_uring/rw.c:1020
 __io_issue_sqe+0x17e/0x4b0 io_uring/io_uring.c:1773
 io_issue_sqe+0x165/0xfd0 io_uring/io_uring.c:1796
 io_wq_submit_work+0x6e9/0xb90 io_uring/io_uring.c:1908
 io_worker_handle_work+0x7cd/0x1180 io_uring/io-wq.c:650
 io_wq_worker+0x42f/0xeb0 io_uring/io-wq.c:704
 ret_from_fork+0x3f9/0x770 arch/x86/kernel/process.c:148
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>


---
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