[syzbot] [io-uring?] INFO: task hung in io_wq_put_and_exit (4)

[syzbot] [io-uring?] INFO: task hung in io_wq_put_and_exit (4)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit:    4d939780b705 Merge tag 'mm-hotfixes-stable-2024-10-17-16-0..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=15f2c240580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=cfbd94c114a3d407
dashboard link: https://syzkaller.appspot.com/bug?extid=58928048fd1416f1457c
compiler:       Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40

Unfortunately, I don't have any reproducer for this issue yet.

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/6510e0507f68/disk-4d939780.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/a1bec5c6d200/vmlinux-4d939780.xz
kernel image: https://storage.googleapis.com/syzbot-assets/91694f5e7961/bzImage-4d939780.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+58928048fd1416f1457c@syzkaller.appspotmail.com

INFO: task syz.2.944:9507 blocked for more than 143 seconds.
      Not tainted 6.12.0-rc3-syzkaller-00217-g4d939780b705 #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.2.944       state:D stack:25744 pid:9507  tgid:9506  ppid:9305   flags:0x00024000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5322 [inline]
 __schedule+0x1895/0x4b30 kernel/sched/core.c:6682
 __schedule_loop kernel/sched/core.c:6759 [inline]
 schedule+0x14b/0x320 kernel/sched/core.c:6774
 schedule_timeout+0xb0/0x310 kernel/time/timer.c:2591
 do_wait_for_common kernel/sched/completion.c:95 [inline]
 __wait_for_common kernel/sched/completion.c:116 [inline]
 wait_for_common kernel/sched/completion.c:127 [inline]
 wait_for_completion+0x355/0x620 kernel/sched/completion.c:148
 io_wq_exit_workers io_uring/io-wq.c:1249 [inline]
 io_wq_put_and_exit+0x344/0x720 io_uring/io-wq.c:1277
 io_uring_clean_tctx+0x168/0x1e0 io_uring/tctx.c:193
 io_uring_cancel_generic+0x76a/0x820 io_uring/io_uring.c:3219
 io_uring_files_cancel include/linux/io_uring.h:20 [inline]
 do_exit+0x6a8/0x28e0 kernel/exit.c:895
 do_group_exit+0x207/0x2c0 kernel/exit.c:1088
 get_signal+0x16a3/0x1740 kernel/signal.c:2917
 arch_do_signal_or_restart+0x96/0x860 arch/x86/kernel/signal.c:337
 exit_to_user_mode_loop kernel/entry/common.c:111 [inline]
 exit_to_user_mode_prepare include/linux/entry-common.h:328 [inline]
 __syscall_exit_to_user_mode_work kernel/entry/common.c:207 [inline]
 syscall_exit_to_user_mode+0xc9/0x370 kernel/entry/common.c:218
 do_syscall_64+0x100/0x230 arch/x86/entry/common.c:89
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f958877dff9
RSP: 002b:00007f95895d30e8 EFLAGS: 00000246 ORIG_RAX: 00000000000000ca
RAX: fffffffffffffe00 RBX: 00007f9588935f88 RCX: 00007f958877dff9
RDX: 0000000000000000 RSI: 0000000000000080 RDI: 00007f9588935f88
RBP: 00007f9588935f80 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007f9588935f8c
R13: 0000000000000000 R14: 00007f9588a5f940 R15: 00007f9588a5fa28
 </TASK>

Showing all locks held in the system:
3 locks held by kworker/u8:1/12:
 #0: ffff88814bf8f148 ((wq_completion)ipv6_addrconf){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3204 [inline]
 #0: ffff88814bf8f148 ((wq_completion)ipv6_addrconf){+.+.}-{0:0}, at: process_scheduled_works+0x93b/0x1850 kernel/workqueue.c:3310
 #1: ffffc90000117d00 ((work_completion)(&(&ifa->dad_work)->work)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3205 [inline]
 #1: ffffc90000117d00 ((work_completion)(&(&ifa->dad_work)->work)){+.+.}-{0:0}, at: process_scheduled_works+0x976/0x1850 kernel/workqueue.c:3310
 #2: ffffffff8fcd2d08 (rtnl_mutex){+.+.}-{3:3}, at: addrconf_dad_work+0xd0/0x16f0 net/ipv6/addrconf.c:4196
1 lock held by khungtaskd/30:
 #0: ffffffff8e937de0 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:337 [inline]
 #0: ffffffff8e937de0 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline]
 #0: ffffffff8e937de0 (rcu_read_lock){....}-{1:2}, at: debug_show_all_locks+0x55/0x2a0 kernel/locking/lockdep.c:6720
6 locks held by kworker/u8:3/52:
 #0: ffff88801baed948 ((wq_completion)netns){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3204 [inline]
 #0: ffff88801baed948 ((wq_completion)netns){+.+.}-{0:0}, at: process_scheduled_works+0x93b/0x1850 kernel/workqueue.c:3310
 #1: ffffc90000bd7d00 (net_cleanup_work){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3205 [inline]
 #1: ffffc90000bd7d00 (net_cleanup_work){+.+.}-{0:0}, at: process_scheduled_works+0x976/0x1850 kernel/workqueue.c:3310
 #2: ffffffff8fcc6210 (pernet_ops_rwsem){++++}-{3:3}, at: cleanup_net+0x16a/0xcc0 net/core/net_namespace.c:580
 #3: ffff8880518ac0e8 (&dev->mutex){....}-{3:3}, at: device_lock include/linux/device.h:1014 [inline]
 #3: ffff8880518ac0e8 (&dev->mutex){....}-{3:3}, at: devl_dev_lock net/devlink/devl_internal.h:108 [inline]
 #3: ffff8880518ac0e8 (&dev->mutex){....}-{3:3}, at: devlink_pernet_pre_exit+0x13b/0x440 net/devlink/core.c:506
 #4: ffff8880518af250 (&devlink->lock_key#45){+.+.}-{3:3}, at: devl_lock net/devlink/core.c:276 [inline]
 #4: ffff8880518af250 (&devlink->lock_key#45){+.+.}-{3:3}, at: devl_dev_lock net/devlink/devl_internal.h:109 [inline]
 #4: ffff8880518af250 (&devlink->lock_key#45){+.+.}-{3:3}, at: devlink_pernet_pre_exit+0x14d/0x440 net/devlink/core.c:506
 #5: ffffffff8fcd2d08 (rtnl_mutex){+.+.}-{3:3}, at: nsim_destroy+0x71/0x5c0 drivers/net/netdevsim/netdev.c:773
2 locks held by dhcpcd/4900:
2 locks held by getty/4984:
 #0: ffff88814d1800a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:243
 #1: ffffc90002f062f0 (&ldata->atomic_read_lock){+.+.}-{3:3}, at: n_tty_read+0x6a6/0x1e00 drivers/tty/n_tty.c:2211
1 lock held by iou-wrk-9507/9508:
 #0: ffff888031f540a8 (&ctx->uring_lock){+.+.}-{3:3}, at: io_ring_submit_lock io_uring/io_uring.h:249 [inline]
 #0: ffff888031f540a8 (&ctx->uring_lock){+.+.}-{3:3}, at: io_provide_buffers+0xd0b/0x1010 io_uring/kbuf.c:580
1 lock held by iou-wrk-9507/9510:
 #0: ffff888031f540a8 (&ctx->uring_lock){+.+.}-{3:3}, at: io_ring_submit_lock io_uring/io_uring.h:249 [inline]
 #0: ffff888031f540a8 (&ctx->uring_lock){+.+.}-{3:3}, at: io_provide_buffers+0xd0b/0x1010 io_uring/kbuf.c:580
1 lock held by iou-wrk-9507/9511:
 #0: ffff888031f540a8 (&ctx->uring_lock){+.+.}-{3:3}, at: io_ring_submit_lock io_uring/io_uring.h:249 [inline]
 #0: ffff888031f540a8 (&ctx->uring_lock){+.+.}-{3:3}, at: io_provide_buffers+0xd0b/0x1010 io_uring/kbuf.c:580
1 lock held by iou-wrk-9507/9512:
 #0: ffff888031f540a8 (&ctx->uring_lock){+.+.}-{3:3}, at: io_ring_submit_lock io_uring/io_uring.h:249 [inline]
 #0: ffff888031f540a8 (&ctx->uring_lock){+.+.}-{3:3}, at: io_provide_buffers+0xd0b/0x1010 io_uring/kbuf.c:580
2 locks held by iou-wrk-9507/9513:
1 lock held by iou-wrk-9507/9514:
 #0: ffff888031f540a8 (&ctx->uring_lock){+.+.}-{3:3}, at: io_ring_submit_lock io_uring/io_uring.h:249 [inline]
 #0: ffff888031f540a8 (&ctx->uring_lock){+.+.}-{3:3}, at: io_provide_buffers+0xd0b/0x1010 io_uring/kbuf.c:580
1 lock held by iou-wrk-9507/9515:
 #0: ffff888031f540a8 (&ctx->uring_lock){+.+.}-{3:3}, at: io_ring_submit_lock io_uring/io_uring.h:249 [inline]
 #0: ffff888031f540a8 (&ctx->uring_lock){+.+.}-{3:3}, at: io_provide_buffers+0xd0b/0x1010 io_uring/kbuf.c:580
1 lock held by iou-wrk-9507/9516:
 #0: ffff888031f540a8 (&ctx->uring_lock){+.+.}-{3:3}, at: io_ring_submit_lock io_uring/io_uring.h:249 [inline]
 #0: ffff888031f540a8 (&ctx->uring_lock){+.+.}-{3:3}, at: io_provide_buffers+0xd0b/0x1010 io_uring/kbuf.c:580
1 lock held by syz.0.1129/10509:
1 lock held by syz-executor/10878:
 #0: ffffffff8e93d378 (rcu_state.exp_mutex){+.+.}-{3:3}, at: exp_funnel_lock kernel/rcu/tree_exp.h:297 [inline]
 #0: ffffffff8e93d378 (rcu_state.exp_mutex){+.+.}-{3:3}, at: synchronize_rcu_expedited+0x381/0x830 kernel/rcu/tree_exp.h:976
1 lock held by syz-executor/11012:
1 lock held by syz-executor/11041:
4 locks held by syz-executor/11109:
1 lock held by syz.0.1245/11222:

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

NMI backtrace for cpu 1
CPU: 1 UID: 0 PID: 30 Comm: khungtaskd Not tainted 6.12.0-rc3-syzkaller-00217-g4d939780b705 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/13/2024
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:94 [inline]
 dump_stack_lvl+0x241/0x360 lib/dump_stack.c:120
 nmi_cpu_backtrace+0x49c/0x4d0 lib/nmi_backtrace.c:113
 nmi_trigger_cpumask_backtrace+0x198/0x320 lib/nmi_backtrace.c:62
 trigger_all_cpu_backtrace include/linux/nmi.h:162 [inline]
 check_hung_uninterruptible_tasks kernel/hung_task.c:223 [inline]
 watchdog+0xff4/0x1040 kernel/hung_task.c:379
 kthread+0x2f0/0x390 kernel/kthread.c:389
 ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:147
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244
 </TASK>
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 UID: 0 PID: 11222 Comm: syz.0.1245 Not tainted 6.12.0-rc3-syzkaller-00217-g4d939780b705 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/13/2024
RIP: 0010:preempt_count kernel/rcu/tree.c:4767 [inline]
RIP: 0010:rcu_lockdep_current_cpu_online+0x6/0x120 kernel/rcu/tree.c:4771
Code: e9 53 ff ff ff 66 2e 0f 1f 84 00 00 00 00 00 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 41 57 <41> 56 53 65 8b 0d f8 a4 88 7e b0 01 f7 c1 00 00 f0 00 0f 85 d5 00
RSP: 0018:ffffc90003c0f7a8 EFLAGS: 00000202
RAX: 0000000000000001 RBX: 0000000000000000 RCX: ffff888025388000
RDX: 0000000000000000 RSI: ffffffff8c610180 RDI: ffffffff8c610140
RBP: 0000000000000140 R08: ffffffff820b6d6e R09: 1ffffffff2859300
R10: dffffc0000000000 R11: fffffbfff2859301 R12: 0000000000055529
R13: ffffea0001554a48 R14: ffffffff820b6ca0 R15: ffff88801bf00000
FS:  0000000000000000(0000) GS:ffff8880b8600000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f401994e5a0 CR3: 000000000e734000 CR4: 00000000003526f0
DR0: 0000000000000003 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400
Call Trace:
 <NMI>
 </NMI>
 <TASK>
 rcu_read_lock_held_common kernel/rcu/update.c:113 [inline]
 rcu_read_lock_held+0x1e/0x50 kernel/rcu/update.c:349
 lookup_page_ext mm/page_ext.c:254 [inline]
 page_ext_get+0x192/0x2a0 mm/page_ext.c:526
 __reset_page_owner+0x30/0x430 mm/page_owner.c:290
 reset_page_owner include/linux/page_owner.h:25 [inline]
 free_pages_prepare mm/page_alloc.c:1108 [inline]
 free_unref_page+0xcfb/0xf20 mm/page_alloc.c:2638
 vfree+0x186/0x2e0 mm/vmalloc.c:3361
 kcov_put kernel/kcov.c:439 [inline]
 kcov_close+0x28/0x50 kernel/kcov.c:535
 __fput+0x23f/0x880 fs/file_table.c:431
 task_work_run+0x24f/0x310 kernel/task_work.c:228
 exit_task_work include/linux/task_work.h:40 [inline]
 do_exit+0xa2f/0x28e0 kernel/exit.c:939
 do_group_exit+0x207/0x2c0 kernel/exit.c:1088
 get_signal+0x16a3/0x1740 kernel/signal.c:2917
 arch_do_signal_or_restart+0x96/0x860 arch/x86/kernel/signal.c:337
 exit_to_user_mode_loop kernel/entry/common.c:111 [inline]
 exit_to_user_mode_prepare include/linux/entry-common.h:328 [inline]
 __syscall_exit_to_user_mode_work kernel/entry/common.c:207 [inline]
 syscall_exit_to_user_mode+0xc9/0x370 kernel/entry/common.c:218
 do_syscall_64+0x100/0x230 arch/x86/entry/common.c:89
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fa6a717dff9
Code: Unable to access opcode bytes at 0x7fa6a717dfcf.
RSP: 002b:00007fa6a7f5d0e8 EFLAGS: 00000246 ORIG_RAX: 00000000000000ca
RAX: fffffffffffffe00 RBX: 00007fa6a7335f88 RCX: 00007fa6a717dff9
RDX: 0000000000000000 RSI: 0000000000000080 RDI: 00007fa6a7335f88
RBP: 00007fa6a7335f80 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007fa6a7335f8c
R13: 0000000000000000 R14: 00007fa6a745f940 R15: 00007fa6a745fa28
 </TASK>


---
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Re: [syzbot] [io-uring?] INFO: task hung in io_wq_put_and_exit (4)

[syzbot]

syzbot has found a reproducer for the following issue on:

HEAD commit:    b423f5a9a61f Merge tag 'acpi-6.12-rc5' of git://git.kernel..
git tree:       upstream
console+strace: https://syzkaller.appspot.com/x/log.txt?x=1393565f980000
kernel config:  https://syzkaller.appspot.com/x/.config?x=fd919c0fc1af4272
dashboard link: https://syzkaller.appspot.com/bug?extid=58928048fd1416f1457c
compiler:       Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=122f04a7980000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=132cbe40580000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/49d1d501eff9/disk-b423f5a9.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/f973ba06cb5d/vmlinux-b423f5a9.xz
kernel image: https://storage.googleapis.com/syzbot-assets/a97302c30f3f/bzImage-b423f5a9.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+58928048fd1416f1457c@syzkaller.appspotmail.com

INFO: task syz-executor295:5876 blocked for more than 143 seconds.
      Not tainted 6.12.0-rc4-syzkaller-00245-gb423f5a9a61f #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz-executor295 state:D stack:25360 pid:5876  tgid:5876  ppid:5861   flags:0x00024002
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5328 [inline]
 __schedule+0x185a/0x4b70 kernel/sched/core.c:6690
 __schedule_loop kernel/sched/core.c:6767 [inline]
 schedule+0x14b/0x320 kernel/sched/core.c:6782
 schedule_timeout+0xb0/0x310 kernel/time/timer.c:2591
 do_wait_for_common kernel/sched/completion.c:95 [inline]
 __wait_for_common kernel/sched/completion.c:116 [inline]
 wait_for_common kernel/sched/completion.c:127 [inline]
 wait_for_completion+0x355/0x620 kernel/sched/completion.c:148
 io_wq_exit_workers io_uring/io-wq.c:1249 [inline]
 io_wq_put_and_exit+0x344/0x720 io_uring/io-wq.c:1277
 io_uring_clean_tctx+0x168/0x1e0 io_uring/tctx.c:193
 io_uring_cancel_generic+0x76a/0x820 io_uring/io_uring.c:3219
 io_uring_files_cancel include/linux/io_uring.h:20 [inline]
 do_exit+0x6a8/0x28e0 kernel/exit.c:895
 do_group_exit+0x207/0x2c0 kernel/exit.c:1088
 __do_sys_exit_group kernel/exit.c:1099 [inline]
 __se_sys_exit_group kernel/exit.c:1097 [inline]
 __x64_sys_exit_group+0x3f/0x40 kernel/exit.c:1097
 x64_sys_call+0x2634/0x2640 arch/x86/include/generated/asm/syscalls_64.h:232
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fdf6e9370f9
RSP: 002b:00007ffcae28c868 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007fdf6e9370f9
RDX: 000000000000003c RSI: 00000000000000e7 RDI: 0000000000000000
RBP: 00007fdf6e9b22d0 R08: ffffffffffffffb8 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007fdf6e9b22d0
R13: 0000000000000000 R14: 00007fdf6e9b2d40 R15: 00007fdf6e908280
 </TASK>
INFO: task syz-executor295:5878 blocked for more than 145 seconds.
      Not tainted 6.12.0-rc4-syzkaller-00245-gb423f5a9a61f #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz-executor295 state:D stack:25136 pid:5878  tgid:5878  ppid:5859   flags:0x00024002
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5328 [inline]
 __schedule+0x185a/0x4b70 kernel/sched/core.c:6690
 __schedule_loop kernel/sched/core.c:6767 [inline]
 schedule+0x14b/0x320 kernel/sched/core.c:6782
 schedule_timeout+0xb0/0x310 kernel/time/timer.c:2591
 do_wait_for_common kernel/sched/completion.c:95 [inline]
 __wait_for_common kernel/sched/completion.c:116 [inline]
 wait_for_common kernel/sched/completion.c:127 [inline]
 wait_for_completion+0x355/0x620 kernel/sched/completion.c:148
 io_wq_exit_workers io_uring/io-wq.c:1249 [inline]
 io_wq_put_and_exit+0x344/0x720 io_uring/io-wq.c:1277
 io_uring_clean_tctx+0x168/0x1e0 io_uring/tctx.c:193
 io_uring_cancel_generic+0x76a/0x820 io_uring/io_uring.c:3219
 io_uring_files_cancel include/linux/io_uring.h:20 [inline]
 do_exit+0x6a8/0x28e0 kernel/exit.c:895
 do_group_exit+0x207/0x2c0 kernel/exit.c:1088
 __do_sys_exit_group kernel/exit.c:1099 [inline]
 __se_sys_exit_group kernel/exit.c:1097 [inline]
 __x64_sys_exit_group+0x3f/0x40 kernel/exit.c:1097
 x64_sys_call+0x2634/0x2640 arch/x86/include/generated/asm/syscalls_64.h:232
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fdf6e9370f9
RSP: 002b:00007ffcae28c868 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007fdf6e9370f9
RDX: 000000000000003c RSI: 00000000000000e7 RDI: 0000000000000000
RBP: 00007fdf6e9b22d0 R08: ffffffffffffffb8 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007fdf6e9b22d0
R13: 0000000000000000 R14: 00007fdf6e9b2d40 R15: 00007fdf6e908280
 </TASK>
INFO: task syz-executor295:5880 blocked for more than 147 seconds.
      Not tainted 6.12.0-rc4-syzkaller-00245-gb423f5a9a61f #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz-executor295 state:D stack:25744 pid:5880  tgid:5880  ppid:5855   flags:0x00024002
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5328 [inline]
 __schedule+0x185a/0x4b70 kernel/sched/core.c:6690
 __schedule_loop kernel/sched/core.c:6767 [inline]
 schedule+0x14b/0x320 kernel/sched/core.c:6782
 schedule_timeout+0xb0/0x310 kernel/time/timer.c:2591
 do_wait_for_common kernel/sched/completion.c:95 [inline]
 __wait_for_common kernel/sched/completion.c:116 [inline]
 wait_for_common kernel/sched/completion.c:127 [inline]
 wait_for_completion+0x355/0x620 kernel/sched/completion.c:148
 io_wq_exit_workers io_uring/io-wq.c:1249 [inline]
 io_wq_put_and_exit+0x344/0x720 io_uring/io-wq.c:1277
 io_uring_clean_tctx+0x168/0x1e0 io_uring/tctx.c:193
 io_uring_cancel_generic+0x76a/0x820 io_uring/io_uring.c:3219
 io_uring_files_cancel include/linux/io_uring.h:20 [inline]
 do_exit+0x6a8/0x28e0 kernel/exit.c:895
 do_group_exit+0x207/0x2c0 kernel/exit.c:1088
 __do_sys_exit_group kernel/exit.c:1099 [inline]
 __se_sys_exit_group kernel/exit.c:1097 [inline]
 __x64_sys_exit_group+0x3f/0x40 kernel/exit.c:1097
 x64_sys_call+0x2634/0x2640 arch/x86/include/generated/asm/syscalls_64.h:232
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fdf6e9370f9
RSP: 002b:00007ffcae28c868 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007fdf6e9370f9
RDX: 000000000000003c RSI: 00000000000000e7 RDI: 0000000000000000
RBP: 00007fdf6e9b22d0 R08: ffffffffffffffb8 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007fdf6e9b22d0
R13: 0000000000000000 R14: 00007fdf6e9b2d40 R15: 00007fdf6e908280
 </TASK>
INFO: task syz-executor295:5884 blocked for more than 148 seconds.
      Not tainted 6.12.0-rc4-syzkaller-00245-gb423f5a9a61f #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz-executor295 state:D stack:25744 pid:5884  tgid:5884  ppid:5856   flags:0x00024002
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5328 [inline]
 __schedule+0x185a/0x4b70 kernel/sched/core.c:6690
 __schedule_loop kernel/sched/core.c:6767 [inline]
 schedule+0x14b/0x320 kernel/sched/core.c:6782
 schedule_timeout+0xb0/0x310 kernel/time/timer.c:2591
 do_wait_for_common kernel/sched/completion.c:95 [inline]
 __wait_for_common kernel/sched/completion.c:116 [inline]
 wait_for_common kernel/sched/completion.c:127 [inline]
 wait_for_completion+0x355/0x620 kernel/sched/completion.c:148
 io_wq_exit_workers io_uring/io-wq.c:1249 [inline]
 io_wq_put_and_exit+0x344/0x720 io_uring/io-wq.c:1277
 io_uring_clean_tctx+0x168/0x1e0 io_uring/tctx.c:193
 io_uring_cancel_generic+0x76a/0x820 io_uring/io_uring.c:3219
 io_uring_files_cancel include/linux/io_uring.h:20 [inline]
 do_exit+0x6a8/0x28e0 kernel/exit.c:895
 do_group_exit+0x207/0x2c0 kernel/exit.c:1088
 __do_sys_exit_group kernel/exit.c:1099 [inline]
 __se_sys_exit_group kernel/exit.c:1097 [inline]
 __x64_sys_exit_group+0x3f/0x40 kernel/exit.c:1097
 x64_sys_call+0x2634/0x2640 arch/x86/include/generated/asm/syscalls_64.h:232
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fdf6e9370f9
RSP: 002b:00007ffcae28c868 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007fdf6e9370f9
RDX: 000000000000003c RSI: 00000000000000e7 RDI: 0000000000000000
RBP: 00007fdf6e9b22d0 R08: ffffffffffffffb8 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007fdf6e9b22d0
R13: 0000000000000000 R14: 00007fdf6e9b2d40 R15: 00007fdf6e908280
 </TASK>
INFO: task syz-executor295:5887 blocked for more than 150 seconds.
      Not tainted 6.12.0-rc4-syzkaller-00245-gb423f5a9a61f #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz-executor295 state:D stack:25360 pid:5887  tgid:5887  ppid:5862   flags:0x00024002
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5328 [inline]
 __schedule+0x185a/0x4b70 kernel/sched/core.c:6690
 __schedule_loop kernel/sched/core.c:6767 [inline]
 schedule+0x14b/0x320 kernel/sched/core.c:6782
 schedule_timeout+0xb0/0x310 kernel/time/timer.c:2591
 do_wait_for_common kernel/sched/completion.c:95 [inline]
 __wait_for_common kernel/sched/completion.c:116 [inline]
 wait_for_common kernel/sched/completion.c:127 [inline]
 wait_for_completion+0x355/0x620 kernel/sched/completion.c:148
 io_wq_exit_workers io_uring/io-wq.c:1249 [inline]
 io_wq_put_and_exit+0x344/0x720 io_uring/io-wq.c:1277
 io_uring_clean_tctx+0x168/0x1e0 io_uring/tctx.c:193
 io_uring_cancel_generic+0x76a/0x820 io_uring/io_uring.c:3219
 io_uring_files_cancel include/linux/io_uring.h:20 [inline]
 do_exit+0x6a8/0x28e0 kernel/exit.c:895
 do_group_exit+0x207/0x2c0 kernel/exit.c:1088
 __do_sys_exit_group kernel/exit.c:1099 [inline]
 __se_sys_exit_group kernel/exit.c:1097 [inline]
 __x64_sys_exit_group+0x3f/0x40 kernel/exit.c:1097
 x64_sys_call+0x2634/0x2640 arch/x86/include/generated/asm/syscalls_64.h:232
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fdf6e9370f9
RSP: 002b:00007ffcae28c868 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007fdf6e9370f9
RDX: 000000000000003c RSI: 00000000000000e7 RDI: 0000000000000000
RBP: 00007fdf6e9b22d0 R08: ffffffffffffffb8 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007fdf6e9b22d0
R13: 0000000000000000 R14: 00007fdf6e9b2d40 R15: 00007fdf6e908280
 </TASK>

Showing all locks held in the system:
3 locks held by kworker/u8:0/11:
1 lock held by khungtaskd/30:
 #0: ffffffff8e937e20 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:337 [inline]
 #0: ffffffff8e937e20 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline]
 #0: ffffffff8e937e20 (rcu_read_lock){....}-{1:2}, at: debug_show_all_locks+0x55/0x2a0 kernel/locking/lockdep.c:6720
3 locks held by kworker/u8:2/35:
3 locks held by kworker/u8:3/52:
3 locks held by kworker/u8:5/148:
2 locks held by getty/5585:
 #0: ffff88803153f0a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:243
 #1: ffffc90002f062f0 (&ldata->atomic_read_lock){+.+.}-{3:3}, at: n_tty_read+0x6a6/0x1e00 drivers/tty/n_tty.c:2211
1 lock held by iou-wrk-5876/5877:
1 lock held by iou-wrk-5878/5881:
3 locks held by kworker/u8:1/5879:
1 lock held by iou-wrk-5880/5882:
1 lock held by iou-wrk-5884/5885:
1 lock held by iou-wrk-5887/5888:

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

NMI backtrace for cpu 1
CPU: 1 UID: 0 PID: 30 Comm: khungtaskd Not tainted 6.12.0-rc4-syzkaller-00245-gb423f5a9a61f #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/13/2024
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:94 [inline]
 dump_stack_lvl+0x241/0x360 lib/dump_stack.c:120
 nmi_cpu_backtrace+0x49c/0x4d0 lib/nmi_backtrace.c:113
 nmi_trigger_cpumask_backtrace+0x198/0x320 lib/nmi_backtrace.c:62
 trigger_all_cpu_backtrace include/linux/nmi.h:162 [inline]
 check_hung_uninterruptible_tasks kernel/hung_task.c:223 [inline]
 watchdog+0xff4/0x1040 kernel/hung_task.c:379
 kthread+0x2f0/0x390 kernel/kthread.c:389
 ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:147
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244
 </TASK>
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 UID: 0 PID: 5888 Comm: iou-wrk-5887 Not tainted 6.12.0-rc4-syzkaller-00245-gb423f5a9a61f #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/13/2024
RIP: 0010:unwind_next_frame+0x17b5/0x22d0 arch/x86/kernel/unwind_orc.c:664
Code: 01 c6 49 8d 55 40 4c 89 ef e8 37 0e 00 00 84 c0 0f 84 66 01 00 00 49 bc 00 00 00 00 00 fc ff df 48 8b 44 24 20 42 0f b6 04 20 <84> c0 0f 85 36 08 00 00 48 8b 6c 24 08 8b 84 24 84 00 00 00 39 45
RSP: 0018:ffffc900041771d0 EFLAGS: 00000202
RAX: 0000000000000000 RBX: ffffffff90add366 RCX: 0000000000000000
RDX: dffffc0000000000 RSI: ffffc90004170000 RDI: ffffc90004177658
RBP: dffffc0000000000 R08: ffffc90004177658 R09: 0000000000000000
R10: ffffc900041772f0 R11: fffff5200082ee60 R12: dffffc0000000000
R13: ffffc900041772a0 R14: ffffffff81fb4fe6 R15: ffffc900041772f0
FS:  000055559112e380(0000) GS:ffff8880b8600000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000055a37bfd3600 CR3: 0000000032e0a000 CR4: 00000000003526f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <NMI>


---
If you want syzbot to run the reproducer, reply with:
#syz test: git://repo/address.git branch-or-commit-hash
If you attach or paste a git patch, syzbot will apply it before testing.

Re: [syzbot] [io-uring?] INFO: task hung in io_wq_put_and_exit (4)

[Jens Axboe]

On 10/25/24 11:43 PM, syzbot wrote:
> syzbot has found a reproducer for the following issue on:
> 
> HEAD commit:    b423f5a9a61f Merge tag 'acpi-6.12-rc5' of git://git.kernel..
> git tree:       upstream
> console+strace: https://syzkaller.appspot.com/x/log.txt?x=1393565f980000
> kernel config:  https://syzkaller.appspot.com/x/.config?x=fd919c0fc1af4272
> dashboard link: https://syzkaller.appspot.com/bug?extid=58928048fd1416f1457c
> compiler:       Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
> syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=122f04a7980000
> C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=132cbe40580000

Perfect thanks, we'll take a look.

-- 
Jens Axboe

Re: [syzbot] [io-uring?] INFO: task hung in io_wq_put_and_exit (4)

[Jens Axboe]

On 10/26/24 7:44 AM, Jens Axboe wrote:
> On 10/25/24 11:43 PM, syzbot wrote:
>> syzbot has found a reproducer for the following issue on:
>>
>> HEAD commit:    b423f5a9a61f Merge tag 'acpi-6.12-rc5' of git://git.kernel..
>> git tree:       upstream
>> console+strace: https://syzkaller.appspot.com/x/log.txt?x=1393565f980000
>> kernel config:  https://syzkaller.appspot.com/x/.config?x=fd919c0fc1af4272
>> dashboard link: https://syzkaller.appspot.com/bug?extid=58928048fd1416f1457c
>> compiler:       Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
>> syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=122f04a7980000
>> C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=132cbe40580000
> 
> Perfect thanks, we'll take a look.

Took a look, and it's one of the usual stupid cases of "let's just flood
it with things and exit will take a while". In this case it's adding a ton
of classic provided buffers, and then exit takes a while to prune them.
Not convinced there's a real bug here, outside of the config have lots
of debug options that slows everything down. It'll finish eventually,
it'll just take a while with how it's being used.

-- 
Jens Axboe

Re: [syzbot] [io-uring?] INFO: task hung in io_wq_put_and_exit (4)

[Jens Axboe]

#syz test: git://git.kernel.dk/linux.git io_uring-6.15

-- 
Jens Axboe

Re: [syzbot] [io-uring?] INFO: task hung in io_wq_put_and_exit (4)

[syzbot]

Hello,

syzbot has tested the proposed patch but the reproducer is still triggering an issue:
unregister_netdevice: waiting for DEV to become free

unregister_netdevice: waiting for batadv0 to become free. Usage count = 3


Tested on:

commit:         d1005530 io_uring/kbuf: conditional schedule on buffer..
git tree:       git://git.kernel.dk/linux.git io_uring-6.15
console output: https://syzkaller.appspot.com/x/log.txt?x=14566fb0580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=dcca8bc6e23acb2
dashboard link: https://syzkaller.appspot.com/bug?extid=58928048fd1416f1457c
compiler:       Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40

Note: no patches were applied.

Re: [syzbot] [io-uring?] INFO: task hung in io_wq_put_and_exit (4)

[Jens Axboe]

On 4/4/25 4:54 PM, syzbot wrote:
> Hello,
> 
> syzbot has tested the proposed patch but the reproducer is still triggering an issue:
> unregister_netdevice: waiting for DEV to become free
> 
> unregister_netdevice: waiting for batadv0 to become free. Usage count = 3

Guess there's some mainline issue causing these failures... Let's try
on a 6.14 base:

#syz test: git://git.kernel.dk/linux.git syztest

-- 
Jens Axboe

Re: [syzbot] [io-uring?] INFO: task hung in io_wq_put_and_exit (4)

[syzbot]

Hello,

syzbot has tested the proposed patch but the reproducer is still triggering an issue:
INFO: task hung in io_wq_put_and_exit

INFO: task syz.0.15:6739 blocked for more than 143 seconds.
      Not tainted 6.14.0-syzkaller-00001-g626e6212aaf6 #0
      Blocked by coredump.
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.0.15        state:D stack:23744 pid:6739  tgid:6738  ppid:6553   task_flags:0x400548 flags:0x00024000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5378 [inline]
 __schedule+0x18bc/0x4c40 kernel/sched/core.c:6765
 __schedule_loop kernel/sched/core.c:6842 [inline]
 schedule+0x14b/0x320 kernel/sched/core.c:6857
 schedule_timeout+0xb0/0x290 kernel/time/sleep_timeout.c:75
 do_wait_for_common kernel/sched/completion.c:95 [inline]
 __wait_for_common kernel/sched/completion.c:116 [inline]
 wait_for_common kernel/sched/completion.c:127 [inline]
 wait_for_completion+0x355/0x620 kernel/sched/completion.c:148
 io_wq_exit_workers io_uring/io-wq.c:1262 [inline]
 io_wq_put_and_exit+0x344/0x720 io_uring/io-wq.c:1290
 io_uring_clean_tctx+0x168/0x1e0 io_uring/tctx.c:205
 io_uring_cancel_generic+0x751/0x800 io_uring/io_uring.c:3183
 io_uring_files_cancel include/linux/io_uring.h:19 [inline]
 do_exit+0x6a3/0x2940 kernel/exit.c:894
 do_group_exit+0x207/0x2c0 kernel/exit.c:1087
 get_signal+0x16b2/0x1750 kernel/signal.c:3036
 arch_do_signal_or_restart+0x96/0x860 arch/x86/kernel/signal.c:337
 exit_to_user_mode_loop kernel/entry/common.c:111 [inline]
 exit_to_user_mode_prepare include/linux/entry-common.h:329 [inline]
 __syscall_exit_to_user_mode_work kernel/entry/common.c:207 [inline]
 syscall_exit_to_user_mode+0xce/0x340 kernel/entry/common.c:218
 do_syscall_64+0x100/0x230 arch/x86/entry/common.c:89
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f2dc697e719
RSP: 002b:00007f2dc77490e8 EFLAGS: 00000246 ORIG_RAX: 00000000000000ca
RAX: fffffffffffffe00 RBX: 00007f2dc6b35f88 RCX: 00007f2dc697e719
RDX: 0000000000000000 RSI: 0000000000000080 RDI: 00007f2dc6b35f88
RBP: 00007f2dc6b35f80 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007f2dc6b35f8c
R13: 0000000000000000 R14: 00007ffdb8b1f290 R15: 00007ffdb8b1f378
 </TASK>
INFO: task syz.4.19:6783 blocked for more than 146 seconds.
      Not tainted 6.14.0-syzkaller-00001-g626e6212aaf6 #0
      Blocked by coredump.
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.4.19        state:D stack:25696 pid:6783  tgid:6779  ppid:6564   task_flags:0x400548 flags:0x00024000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5378 [inline]
 __schedule+0x18bc/0x4c40 kernel/sched/core.c:6765
 __schedule_loop kernel/sched/core.c:6842 [inline]
 schedule+0x14b/0x320 kernel/sched/core.c:6857
 schedule_timeout+0xb0/0x290 kernel/time/sleep_timeout.c:75
 do_wait_for_common kernel/sched/completion.c:95 [inline]
 __wait_for_common kernel/sched/completion.c:116 [inline]
 wait_for_common kernel/sched/completion.c:127 [inline]
 wait_for_completion+0x355/0x620 kernel/sched/completion.c:148
 io_wq_exit_workers io_uring/io-wq.c:1262 [inline]
 io_wq_put_and_exit+0x344/0x720 io_uring/io-wq.c:1290
 io_uring_clean_tctx+0x168/0x1e0 io_uring/tctx.c:205
 io_uring_cancel_generic+0x751/0x800 io_uring/io_uring.c:3183
 io_uring_files_cancel include/linux/io_uring.h:19 [inline]
 do_exit+0x6a3/0x2940 kernel/exit.c:894
 do_group_exit+0x207/0x2c0 kernel/exit.c:1087
 get_signal+0x16b2/0x1750 kernel/signal.c:3036
 arch_do_signal_or_restart+0x96/0x860 arch/x86/kernel/signal.c:337
 exit_to_user_mode_loop kernel/entry/common.c:111 [inline]
 exit_to_user_mode_prepare include/linux/entry-common.h:329 [inline]
 __syscall_exit_to_user_mode_work kernel/entry/common.c:207 [inline]
 syscall_exit_to_user_mode+0xce/0x340 kernel/entry/common.c:218
 do_syscall_64+0x100/0x230 arch/x86/entry/common.c:89
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f6cf337e719
RSP: 002b:00007f6cf40d00e8 EFLAGS: 00000246 ORIG_RAX: 00000000000000ca
RAX: fffffffffffffe00 RBX: 00007f6cf3535f88 RCX: 00007f6cf337e719
RDX: 0000000000000000 RSI: 0000000000000080 RDI: 00007f6cf3535f88
RBP: 00007f6cf3535f80 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007f6cf3535f8c
R13: 0000000000000000 R14: 00007ffd41156d10 R15: 00007ffd41156df8
 </TASK>
INFO: task syz.2.17:6784 blocked for more than 148 seconds.
      Not tainted 6.14.0-syzkaller-00001-g626e6212aaf6 #0
      Blocked by coredump.
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.2.17        state:D stack:23744 pid:6784  tgid:6780  ppid:6562   task_flags:0x400548 flags:0x00024000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5378 [inline]
 __schedule+0x18bc/0x4c40 kernel/sched/core.c:6765
 __schedule_loop kernel/sched/core.c:6842 [inline]
 schedule+0x14b/0x320 kernel/sched/core.c:6857
 schedule_timeout+0xb0/0x290 kernel/time/sleep_timeout.c:75
 do_wait_for_common kernel/sched/completion.c:95 [inline]
 __wait_for_common kernel/sched/completion.c:116 [inline]
 wait_for_common kernel/sched/completion.c:127 [inline]
 wait_for_completion+0x355/0x620 kernel/sched/completion.c:148
 io_wq_exit_workers io_uring/io-wq.c:1262 [inline]
 io_wq_put_and_exit+0x344/0x720 io_uring/io-wq.c:1290
 io_uring_clean_tctx+0x168/0x1e0 io_uring/tctx.c:205
 io_uring_cancel_generic+0x751/0x800 io_uring/io_uring.c:3183
 io_uring_files_cancel include/linux/io_uring.h:19 [inline]
 do_exit+0x6a3/0x2940 kernel/exit.c:894
 do_group_exit+0x207/0x2c0 kernel/exit.c:1087
 get_signal+0x16b2/0x1750 kernel/signal.c:3036
 arch_do_signal_or_restart+0x96/0x860 arch/x86/kernel/signal.c:337
 exit_to_user_mode_loop kernel/entry/common.c:111 [inline]
 exit_to_user_mode_prepare include/linux/entry-common.h:329 [inline]
 __syscall_exit_to_user_mode_work kernel/entry/common.c:207 [inline]
 syscall_exit_to_user_mode+0xce/0x340 kernel/entry/common.c:218
 do_syscall_64+0x100/0x230 arch/x86/entry/common.c:89
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fbb9517e719
RSP: 002b:00007fbb95f3b0e8 EFLAGS: 00000246 ORIG_RAX: 00000000000000ca
RAX: fffffffffffffe00 RBX: 00007fbb95335f88 RCX: 00007fbb9517e719
RDX: 0000000000000000 RSI: 0000000000000080 RDI: 00007fbb95335f88
RBP: 00007fbb95335f80 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007fbb95335f8c
R13: 0000000000000000 R14: 00007ffc20ba6bf0 R15: 00007ffc20ba6cd8
 </TASK>
INFO: task syz.3.18:6820 blocked for more than 151 seconds.
      Not tainted 6.14.0-syzkaller-00001-g626e6212aaf6 #0
      Blocked by coredump.
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.3.18        state:D stack:25184 pid:6820  tgid:6819  ppid:6563   task_flags:0x400548 flags:0x00024000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5378 [inline]
 __schedule+0x18bc/0x4c40 kernel/sched/core.c:6765
 __schedule_loop kernel/sched/core.c:6842 [inline]
 schedule+0x14b/0x320 kernel/sched/core.c:6857
 schedule_timeout+0xb0/0x290 kernel/time/sleep_timeout.c:75
 do_wait_for_common kernel/sched/completion.c:95 [inline]
 __wait_for_common kernel/sched/completion.c:116 [inline]
 wait_for_common kernel/sched/completion.c:127 [inline]
 wait_for_completion+0x355/0x620 kernel/sched/completion.c:148
 io_wq_exit_workers io_uring/io-wq.c:1262 [inline]
 io_wq_put_and_exit+0x344/0x720 io_uring/io-wq.c:1290
 io_uring_clean_tctx+0x168/0x1e0 io_uring/tctx.c:205
 io_uring_cancel_generic+0x751/0x800 io_uring/io_uring.c:3183
 io_uring_files_cancel include/linux/io_uring.h:19 [inline]
 do_exit+0x6a3/0x2940 kernel/exit.c:894


Tested on:

commit:         626e6212 io_uring/kbuf: conditional schedule on buffer..
git tree:       git://git.kernel.dk/linux.git syztest
console output: https://syzkaller.appspot.com/x/log.txt?x=105c9b4c580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=a3f7ddbc4e0c74f1
dashboard link: https://syzkaller.appspot.com/bug?extid=58928048fd1416f1457c
compiler:       Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40

Note: no patches were applied.

Re: [syzbot] [io-uring?] INFO: task hung in io_wq_put_and_exit (4)

[Jens Axboe]

#syz test: git://git.kernel.dk/linux.git syztest

-- 
Jens Axboe

Re: [syzbot] [io-uring?] INFO: task hung in io_wq_put_and_exit (4)

[syzbot]

Hello,

syzbot has tested the proposed patch and the reproducer did not trigger any issue:

Reported-by: syzbot+58928048fd1416f1457c@syzkaller.appspotmail.com
Tested-by: syzbot+58928048fd1416f1457c@syzkaller.appspotmail.com

Tested on:

commit:         881bc75c io_uring/kbuf: reject zero sized provided buf..
git tree:       git://git.kernel.dk/linux.git syztest
console output: https://syzkaller.appspot.com/x/log.txt?x=17420070580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=a3f7ddbc4e0c74f1
dashboard link: https://syzkaller.appspot.com/bug?extid=58928048fd1416f1457c
compiler:       Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40

Note: no patches were applied.
Note: testing is done by a robot and is best-effort only.