[syzbot] [kernel?] INFO: task hung in rxrpc_destroy_all_locals

[syzbot <syzbot+5eb4cf50d2a64db5d9af@syzkaller.appspotmail.com>]

Hello,

syzbot found the following issue on:

HEAD commit:    ad9a728a3388 Merge tag 'for-linus-iommufd' of git://git.ke..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=1710bbfa580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=df890e720d1bb80
dashboard link: https://syzkaller.appspot.com/bug?extid=5eb4cf50d2a64db5d9af
compiler:       gcc (Debian 14.2.0-19) 14.2.0, GNU ld (GNU Binutils for Debian) 2.44

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

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/1b45335ce36e/disk-ad9a728a.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/5c4122232bf5/vmlinux-ad9a728a.xz
kernel image: https://storage.googleapis.com/syzbot-assets/7628c16f6157/bzImage-ad9a728a.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+5eb4cf50d2a64db5d9af@syzkaller.appspotmail.com

INFO: task kworker/u8:5:196 blocked for more than 143 seconds.
      Tainted: G             L      syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:kworker/u8:5    state:D stack:25128 pid:196   tgid:196   ppid:2      task_flags:0x4208160 flags:0x00080000
Workqueue: netns cleanup_net
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5260 [inline]
 __schedule+0xfe4/0x5e10 kernel/sched/core.c:6867
 __schedule_loop kernel/sched/core.c:6949 [inline]
 schedule+0xdd/0x390 kernel/sched/core.c:6964
 schedule_timeout+0x1b2/0x280 kernel/time/sleep_timeout.c:75
 do_wait_for_common kernel/sched/completion.c:100 [inline]
 __wait_for_common+0x2e7/0x4c0 kernel/sched/completion.c:121
 __flush_workqueue+0x3f7/0x1200 kernel/workqueue.c:4033
 rxrpc_destroy_all_locals+0x3e/0x190 net/rxrpc/local_object.c:475
 rxrpc_exit_net+0x8b/0xc0 net/rxrpc/net_ns.c:115
 ops_exit_list net/core/net_namespace.c:199 [inline]
 ops_undo_list+0x2ee/0xab0 net/core/net_namespace.c:252
 cleanup_net+0x419/0x830 net/core/net_namespace.c:696
 process_one_work+0x9c2/0x1840 kernel/workqueue.c:3257
 process_scheduled_works kernel/workqueue.c:3340 [inline]
 worker_thread+0x5da/0xe40 kernel/workqueue.c:3421
 kthread+0x3b3/0x730 kernel/kthread.c:463
 ret_from_fork+0x754/0xaf0 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:246
 </TASK>

Showing all locks held in the system:
1 lock held by khungtaskd/31:
 #0: ffffffff8e5e3120 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:331 [inline]
 #0: ffffffff8e5e3120 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:867 [inline]
 #0: ffffffff8e5e3120 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x3d/0x184 kernel/locking/lockdep.c:6775
3 locks held by kworker/u8:5/196:
 #0: ffff88801c29f148 ((wq_completion)netns){+.+.}-{0:0}, at: process_one_work+0x11ae/0x1840 kernel/workqueue.c:3232
 #1: ffffc90003017c98 (net_cleanup_work){+.+.}-{0:0}, at: process_one_work+0x927/0x1840 kernel/workqueue.c:3233
 #2: ffffffff903dcef0 (pernet_ops_rwsem){++++}-{4:4}, at: cleanup_net+0xab/0x830 net/core/net_namespace.c:670
2 locks held by getty/9827:
 #0: ffff888035bd80a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x24/0x80 drivers/tty/tty_ldisc.c:243
 #1: ffffc900044332f0 (&ldata->atomic_read_lock){+.+.}-{4:4}, at: n_tty_read+0x419/0x1500 drivers/tty/n_tty.c:2211
1 lock held by syz.1.1096/11746:
 #0: ffffffff903dcef0 (pernet_ops_rwsem){++++}-{4:4}, at: copy_net_ns+0x451/0x7c0 net/core/net_namespace.c:577
1 lock held by syz.3.1101/11791:
 #0: ffffffff903dcef0 (pernet_ops_rwsem){++++}-{4:4}, at: copy_net_ns+0x451/0x7c0 net/core/net_namespace.c:577
1 lock held by syz.6.1133/11923:
 #0: ffffffff903dcef0 (pernet_ops_rwsem){++++}-{4:4}, at: copy_net_ns+0x451/0x7c0 net/core/net_namespace.c:577
1 lock held by syz.9.1221/12496:
 #0: ffffffff903dcef0 (pernet_ops_rwsem){++++}-{4:4}, at: copy_net_ns+0x451/0x7c0 net/core/net_namespace.c:577
1 lock held by syz.5.1232/12548:
 #0: ffffffff903dcef0 (pernet_ops_rwsem){++++}-{4:4}, at: copy_net_ns+0x451/0x7c0 net/core/net_namespace.c:577
1 lock held by syz.2.1330/13262:
 #0: ffffffff903dcef0 (pernet_ops_rwsem){++++}-{4:4}, at: copy_net_ns+0x451/0x7c0 net/core/net_namespace.c:577
1 lock held by syz.8.1513/14257:
 #0: ffff8880a725aa48 (&sb->s_type->i_mutex_key#13){+.+.}-{4:4}, at: inode_lock include/linux/fs.h:1027 [inline]
 #0: ffff8880a725aa48 (&sb->s_type->i_mutex_key#13){+.+.}-{4:4}, at: __sock_release+0x86/0x260 net/socket.c:661

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

NMI backtrace for cpu 1
CPU: 1 UID: 0 PID: 31 Comm: khungtaskd Tainted: G             L      syzkaller #0 PREEMPT(full) 
Tainted: [L]=SOFTLOCKUP
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/24/2026
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:94 [inline]
 dump_stack_lvl+0x100/0x190 lib/dump_stack.c:120
 nmi_cpu_backtrace.cold+0x12d/0x151 lib/nmi_backtrace.c:113
 nmi_trigger_cpumask_backtrace+0x1d7/0x230 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+0x141/0x190 lib/sys_info.c:165
 check_hung_uninterruptible_tasks kernel/hung_task.c:346 [inline]
 watchdog+0xcc3/0xfe0 kernel/hung_task.c:515
 kthread+0x3b3/0x730 kernel/kthread.c:463
 ret_from_fork+0x754/0xaf0 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:246
 </TASK>
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 UID: 0 PID: 14266 Comm: kworker/u11:33 Tainted: G             L      syzkaller #0 PREEMPT(full) 
Tainted: [L]=SOFTLOCKUP
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/24/2026
Workqueue: writeback wb_workfn (flush-8:0)
RIP: 0010:__sanitizer_cov_trace_pc+0xb/0x70 kernel/kcov.c:213
Code: 5d 00 be 03 00 00 00 5b e9 f2 a8 de 02 66 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 f3 0f 1e fa 65 8b 05 a5 85 dd 11 <48> 8b 34 24 65 48 8b 15 81 85 dd 11 a9 00 01 ff 00 74 1b f6 c4 01
RSP: 0018:ffffc90000007e10 EFLAGS: 00000002
RAX: 0000000080010002 RBX: ffffc90003e3fd60 RCX: ffffffff81f26bf4
RDX: 0000000000000001 RSI: 0000000000000000 RDI: ffff888032e55b80
RBP: ffff8880b84284c0 R08: 0000000000000001 R09: 0000000000000000
R10: 0000000000000001 R11: 0000000000000001 R12: 0000000000000001
R13: 0000000000000000 R14: ffff8880b8428440 R15: 0000000000000000
FS:  0000000000000000(0000) GS:ffff8881245e3000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f41649e3358 CR3: 0000000076524000 CR4: 00000000003526f0
Call Trace:
 <IRQ>
 __remove_hrtimer+0x92/0x2a0 kernel/time/hrtimer.c:1114
 __run_hrtimer kernel/time/hrtimer.c:1757 [inline]
 __hrtimer_run_queues+0x40c/0x990 kernel/time/hrtimer.c:1841
 hrtimer_interrupt+0x397/0x8c0 kernel/time/hrtimer.c:1903
 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1045 [inline]
 __sysvec_apic_timer_interrupt+0x109/0x3c0 arch/x86/kernel/apic/apic.c:1062
 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1056 [inline]
 sysvec_apic_timer_interrupt+0x9e/0xc0 arch/x86/kernel/apic/apic.c:1056
 </IRQ>
 <TASK>
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:697
RIP: 0010:console_trylock_spinning kernel/printk/printk.c:2037 [inline]
RIP: 0010:vprintk_emit+0x553/0x6b0 kernel/printk/printk.c:2425
Code: 00 4d 85 ed 0f 85 1b 01 00 00 e8 c8 07 21 00 9c 5d 81 e5 00 02 00 00 31 ff 48 89 ee e8 96 02 21 00 48 85 ed 0f 85 27 01 00 00 <e8> a8 07 21 00 45 31 c9 41 b8 01 00 00 00 31 c9 48 8d 05 00 00 00
RSP: 0018:ffffc9000480eee0 EFLAGS: 00000293
RAX: 0000000000000000 RBX: 0000000000000074 RCX: ffffffff81e543ea
RDX: ffff888032e55b80 RSI: ffffffff81e543f4 RDI: ffff888032e55b80
RBP: 0000000000000000 R08: 0000000000000007 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: 1ffff92000901dde
R13: 0000000000000200 R14: ffff88801e6d9e80 R15: ffffc9000480efa8
 _printk+0xcf/0x110 kernel/printk/printk.c:2451
 __ext4_msg.cold+0x9f/0xa1 fs/ext4/super.c:990
 mpage_map_and_submit_extent fs/ext4/inode.c:2499 [inline]
 ext4_do_writepages+0x2e28/0x3df0 fs/ext4/inode.c:2932
 ext4_writepages+0x347/0x790 fs/ext4/inode.c:3026
 do_writepages+0x278/0x600 mm/page-writeback.c:2598
 __writeback_single_inode+0x164/0x13c0 fs/fs-writeback.c:1737
 writeback_sb_inodes+0x72e/0x1b90 fs/fs-writeback.c:2030
 __writeback_inodes_wb+0xf8/0x2d0 fs/fs-writeback.c:2107
 wb_writeback+0x6b4/0xab0 fs/fs-writeback.c:2218
 wb_check_old_data_flush fs/fs-writeback.c:2322 [inline]
 wb_do_writeback fs/fs-writeback.c:2375 [inline]
 wb_workfn+0x885/0xbb0 fs/fs-writeback.c:2403
 process_one_work+0x9c2/0x1840 kernel/workqueue.c:3257
 process_scheduled_works kernel/workqueue.c:3340 [inline]
 worker_thread+0x5da/0xe40 kernel/workqueue.c:3421
 kthread+0x3b3/0x730 kernel/kthread.c:463
 ret_from_fork+0x754/0xaf0 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:246
 </TASK>


---
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