syzbot

INFO: task kworker/u8:6:3547 blocked for more than 143 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:kworker/u8:6    state:D stack:25400 pid:3547  tgid:3547  ppid:2      task_flags:0x4208060 flags:0x00004000
Workqueue: events_unbound netfs_write_collection_worker
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5357 [inline]
 __schedule+0x1190/0x5de0 kernel/sched/core.c:6961
 __schedule_loop kernel/sched/core.c:7043 [inline]
 schedule+0xe7/0x3a0 kernel/sched/core.c:7058
 netfs_wait_for_in_progress_stream+0x17a/0x440 fs/netfs/misc.c:370
 netfs_retry_writes+0x1394/0x19c0 fs/netfs/write_retry.c:214
 netfs_collect_write_results fs/netfs/write_collect.c:349 [inline]
 netfs_write_collection+0x19ee/0x36d0 fs/netfs/write_collect.c:365
 netfs_write_collection_worker+0xea/0x1d0 fs/netfs/write_collect.c:448
 process_one_work+0x9cf/0x1b70 kernel/workqueue.c:3236
 process_scheduled_works kernel/workqueue.c:3319 [inline]
 worker_thread+0x6c8/0xf10 kernel/workqueue.c:3400
 kthread+0x3c2/0x780 kernel/kthread.c:463
 ret_from_fork+0x5d7/0x6f0 arch/x86/kernel/process.c:148
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>

Showing all locks held in the system:
2 locks held by kworker/u8:0/12:
 #0: ffff88801b881148 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_one_work+0x12a2/0x1b70 kernel/workqueue.c:3211
 #1: ffffc90000117d10 ((work_completion)(&rreq->work)){+.+.}-{0:0}, at: process_one_work+0x929/0x1b70 kernel/workqueue.c:3212
2 locks held by kworker/u8:1/13:
 #0: ffff88801b881148 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_one_work+0x12a2/0x1b70 kernel/workqueue.c:3211
 #1: ffffc90000127d10 ((work_completion)(&rreq->work)){+.+.}-{0:0}, at: process_one_work+0x929/0x1b70 kernel/workqueue.c:3212
1 lock held by khungtaskd/31:
 #0: ffffffff8e5c1220 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:331 [inline]
 #0: ffffffff8e5c1220 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:841 [inline]
 #0: ffffffff8e5c1220 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x36/0x1c0 kernel/locking/lockdep.c:6775
2 locks held by kworker/u8:2/36:
 #0: ffff88801b881148 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_one_work+0x12a2/0x1b70 kernel/workqueue.c:3211
 #1: ffffc90000ac7d10 ((work_completion)(&rreq->work)){+.+.}-{0:0}, at: process_one_work+0x929/0x1b70 kernel/workqueue.c:3212
2 locks held by kworker/u8:3/37:
 #0: ffff88801b881148 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_one_work+0x12a2/0x1b70 kernel/workqueue.c:3211
 #1: ffffc90000ad7d10 ((work_completion)(&rreq->work)){+.+.}-{0:0}, at: process_one_work+0x929/0x1b70 kernel/workqueue.c:3212
2 locks held by kworker/u8:4/64:
 #0: ffff88801b881148 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_one_work+0x12a2/0x1b70 kernel/workqueue.c:3211
 #1: ffffc9000212fd10 ((work_completion)(&rreq->work)){+.+.}-{0:0}, at: process_one_work+0x929/0x1b70 kernel/workqueue.c:3212
2 locks held by kworker/u8:5/1001:
 #0: ffff88801b881148 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_one_work+0x12a2/0x1b70 kernel/workqueue.c:3211
 #1: ffffc90003b0fd10 ((work_completion)(&rreq->work)){+.+.}-{0:0}, at: process_one_work+0x929/0x1b70 kernel/workqueue.c:3212
2 locks held by kworker/u8:6/3547:
 #0: ffff88801b881148 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_one_work+0x12a2/0x1b70 kernel/workqueue.c:3211
 #1: ffffc9000cd37d10 ((work_completion)(&rreq->work)){+.+.}-{0:0}, at: process_one_work+0x929/0x1b70 kernel/workqueue.c:3212
2 locks held by kworker/u8:7/3561:
 #0: ffff88801b881148 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_one_work+0x12a2/0x1b70 kernel/workqueue.c:3211
 #1: ffffc9000ccb7d10 ((work_completion)(&rreq->work)){+.+.}-{0:0}, at: process_one_work+0x929/0x1b70 kernel/workqueue.c:3212
2 locks held by kworker/u8:8/3588:
 #0: ffff88801b881148 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_one_work+0x12a2/0x1b70 kernel/workqueue.c:3211
 #1: ffffc9000ce07d10 ((work_completion)(&rreq->work)){+.+.}-{0:0}, at: process_one_work+0x929/0x1b70 kernel/workqueue.c:3212
2 locks held by getty/5605:
 #0: ffff8880327ef0a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x24/0x80 drivers/tty/tty_ldisc.c:243
 #1: ffffc9000332b2f0 (&ldata->atomic_read_lock){+.+.}-{4:4}, at: n_tty_read+0x41b/0x14f0 drivers/tty/n_tty.c:2222
1 lock held by syz.0.17/6047:
 #0: ffff88805fb50500 (&ctx->wb_lock){+.+.}-{4:4}, at: netfs_writepages+0xba/0x920 fs/netfs/write_issue.c:559
1 lock held by syz.1.18/6068:
 #0: ffff88805fb50b70 (&ctx->wb_lock){+.+.}-{4:4}, at: netfs_writepages+0xba/0x920 fs/netfs/write_issue.c:559
1 lock held by syz.2.20/6097:
 #0: ffff88805b4e0500 (&ctx->wb_lock){+.+.}-{4:4}, at: netfs_writepages+0xba/0x920 fs/netfs/write_issue.c:559
1 lock held by syz.3.22/6123:
 #0: ffff88805fb51ec0 (&ctx->wb_lock){+.+.}-{4:4}, at: netfs_writepages+0xba/0x920 fs/netfs/write_issue.c:559
1 lock held by syz.4.23/6151:
 #0: ffff88805fb52530 (&ctx->wb_lock){+.+.}-{4:4}, at: netfs_writepages+0xba/0x920 fs/netfs/write_issue.c:559
2 locks held by kworker/u8:10/6170:
 #0: ffff88801b881148 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_one_work+0x12a2/0x1b70 kernel/workqueue.c:3211
 #1: ffffc90003217d10 ((work_completion)(&rreq->work)){+.+.}-{0:0}, at: process_one_work+0x929/0x1b70 kernel/workqueue.c:3212
1 lock held by syz.5.24/6181:
 #0: ffff88805fb51850 (&ctx->wb_lock){+.+.}-{4:4}, at: netfs_writepages+0xba/0x920 fs/netfs/write_issue.c:559
1 lock held by syz.6.25/6214:
 #0: ffff88805fb52ba0 (&ctx->wb_lock){+.+.}-{4:4}, at: netfs_writepages+0xba/0x920 fs/netfs/write_issue.c:559
1 lock held by syz.7.26/6244:
 #0: ffff88805b4e0b70 (&ctx->wb_lock){+.+.}-{4:4}, at: netfs_writepages+0xba/0x920 fs/netfs/write_issue.c:559
1 lock held by syz.8.29/6276:
 #0: ffff88805b4e11e0 (&ctx->wb_lock){+.+.}-{4:4}, at: netfs_writepages+0xba/0x920 fs/netfs/write_issue.c:559
2 locks held by kworker/u8:14/6298:
 #0: ffff8880b853a318 (&rq->__lock){-.-.}-{2:2}, at: raw_spin_rq_lock_nested+0x29/0x130 kernel/sched/core.c:636
 #1: ffffc90002df7d10 ((work_completion)(&rdev->wiphy_work)){+.+.}-{0:0}, at: process_one_work+0x929/0x1b70 kernel/workqueue.c:3212
1 lock held by syz.9.30/6308:
 #0: ffff88805b4e1850 (&ctx->wb_lock){+.+.}-{4:4}, at: netfs_writepages+0xba/0x920 fs/netfs/write_issue.c:559

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

NMI backtrace for cpu 0
CPU: 0 UID: 0 PID: 31 Comm: khungtaskd Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:94 [inline]
 dump_stack_lvl+0x116/0x1f0 lib/dump_stack.c:120
 nmi_cpu_backtrace+0x27b/0x390 lib/nmi_backtrace.c:113
 nmi_trigger_cpumask_backtrace+0x29c/0x300 lib/nmi_backtrace.c:62
 trigger_all_cpu_backtrace include/linux/nmi.h:160 [inline]
 check_hung_uninterruptible_tasks kernel/hung_task.c:328 [inline]
 watchdog+0xf0e/0x1260 kernel/hung_task.c:491
 kthread+0x3c2/0x780 kernel/kthread.c:463
 ret_from_fork+0x5d7/0x6f0 arch/x86/kernel/process.c:148
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 UID: 0 PID: 6298 Comm: kworker/u8:14 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025
Workqueue: bat_events batadv_nc_worker
RIP: 0010:hlock_class+0x4/0x70 kernel/locking/lockdep.c:229
Code: 0f 0b 90 e9 01 ff ff ff 66 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 00 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 0f b7 47 20 <66> 25 ff 1f 0f b7 c0 48 0f a3 05 4d c1 45 14 73 15 48 8d 04 80 48
RSP: 0018:ffffc90002df79d8 EFLAGS: 00000002
RAX: 0000000000000007 RBX: ffff8880793a8af0 RCX: 0000000000020000
RDX: 0000000000000007 RSI: 0000000000000000 RDI: ffff8880793a8b40
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000050 R11: 0000000000000001 R12: ffff8880793a8b40
R13: ffff8880793a8000 R14: 0000000000000000 R15: ffffffff8e5c1220
FS:  0000000000000000(0000) GS:ffff8881247bb000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000555865f5dbe0 CR3: 000000000e380000 CR4: 00000000003526f0
Call Trace:
 <TASK>
 check_wait_context kernel/locking/lockdep.c:4854 [inline]
 __lock_acquire+0x218/0x1ce0 kernel/locking/lockdep.c:5187
 lock_acquire kernel/locking/lockdep.c:5868 [inline]
 lock_acquire+0x179/0x350 kernel/locking/lockdep.c:5825
 rcu_lock_acquire include/linux/rcupdate.h:331 [inline]
 rcu_read_lock include/linux/rcupdate.h:841 [inline]
 batadv_nc_purge_orig_hash net/batman-adv/network-coding.c:408 [inline]
 batadv_nc_worker+0x16a/0x1030 net/batman-adv/network-coding.c:719
 process_one_work+0x9cf/0x1b70 kernel/workqueue.c:3236
 process_scheduled_works kernel/workqueue.c:3319 [inline]
 worker_thread+0x6c8/0xf10 kernel/workqueue.c:3400
 kthread+0x3c2/0x780 kernel/kthread.c:463
 ret_from_fork+0x5d7/0x6f0 arch/x86/kernel/process.c:148
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>