syzbot

INFO: task syz.2.1342:10392 blocked for more than 143 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.2.1342      state:D stack:25752 pid:10392 tgid:10389 ppid:5812   task_flags:0x400040 flags:0x00080003
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5325 [inline]
 __schedule+0x1190/0x5de0 kernel/sched/core.c:6929
 __schedule_loop kernel/sched/core.c:7011 [inline]
 schedule+0xe7/0x3a0 kernel/sched/core.c:7026
 io_schedule+0xbf/0x130 kernel/sched/core.c:7871
 folio_wait_bit_common+0x3d5/0x9e0 mm/filemap.c:1317
 folio_lock include/linux/pagemap.h:1151 [inline]
 migrate_folio_unmap mm/migrate.c:1241 [inline]
 migrate_pages_batch+0x1487/0x3bb0 mm/migrate.c:1882
 migrate_pages_sync+0x4c5/0x8a0 mm/migrate.c:2026
 migrate_pages+0x1b5f/0x23a0 mm/migrate.c:2108
 compact_zone+0x2018/0x4750 mm/compaction.c:2647
 compact_node+0x1a3/0x2c0 mm/compaction.c:2916
 compact_nodes mm/compaction.c:2938 [inline]
 sysctl_compaction_handler mm/compaction.c:2989 [inline]
 sysctl_compaction_handler+0x141/0x210 mm/compaction.c:2976
 proc_sys_call_handler+0x445/0x570 fs/proc/proc_sysctl.c:600
 iter_file_splice_write+0xa24/0x12e0 fs/splice.c:738
 do_splice_from fs/splice.c:938 [inline]
 direct_splice_actor+0x192/0x6c0 fs/splice.c:1161
 splice_direct_to_actor+0x345/0xa30 fs/splice.c:1105
 do_splice_direct_actor fs/splice.c:1204 [inline]
 do_splice_direct+0x174/0x240 fs/splice.c:1230
 do_sendfile+0xb06/0xe50 fs/read_write.c:1370
 __do_sys_sendfile64 fs/read_write.c:1425 [inline]
 __se_sys_sendfile64 fs/read_write.c:1417 [inline]
 __x64_sys_sendfile64+0x154/0x220 fs/read_write.c:1417
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xcd/0xfa0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f572878f749
RSP: 002b:00007f57269f6038 EFLAGS: 00000246 ORIG_RAX: 0000000000000028
RAX: ffffffffffffffda RBX: 00007f57289e5fa0 RCX: 00007f572878f749
RDX: 00002000000000c0 RSI: 0000000000000004 RDI: 0000000000000005
RBP: 00007f5728813f91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000005 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f57289e6038 R14: 00007f57289e5fa0 R15: 00007ffd5ef66558
 </TASK>

Showing all locks held in the system:
1 lock held by khungtaskd/31:
 #0: ffffffff8e3c4020 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:331 [inline]
 #0: ffffffff8e3c4020 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:867 [inline]
 #0: ffffffff8e3c4020 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x36/0x1c0 kernel/locking/lockdep.c:6775
2 locks held by getty/5574:
 #0: ffff8880352ed0a0 (&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
2 locks held by kworker/1:7/5888:
 #0: ffff8880b843a398 (&rq->__lock){-.-.}-{2:2}, at: raw_spin_rq_lock_nested kernel/sched/core.c:646 [inline]
 #0: ffff8880b843a398 (&rq->__lock){-.-.}-{2:2}, at: raw_spin_rq_lock_nested+0x7e/0x130 kernel/sched/core.c:631
 #1: ffff8880b8524088 (psi_seq){-.-.}-{0:0}, at: psi_sched_switch kernel/sched/stats.h:220 [inline]
 #1: ffff8880b8524088 (psi_seq){-.-.}-{0:0}, at: __schedule+0x1861/0x5de0 kernel/sched/core.c:6923
1 lock held by udevd/5968:
 #0: ffff888143b20358 (&disk->open_mutex){+.+.}-{4:4}, at: bdev_open+0x41a/0xe40 block/bdev.c:962
1 lock held by syz.2.1342/10392:
 #0: ffff888021b7a420 (sb_writers#3){.+.+}-{0:0}, at: splice_direct_to_actor+0x345/0xa30 fs/splice.c:1105

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

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 10/25/2025
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:332 [inline]
 watchdog+0xf3f/0x1170 kernel/hung_task.c:495
 kthread+0x3c5/0x780 kernel/kthread.c:463
 ret_from_fork+0x675/0x7d0 arch/x86/kernel/process.c:158
 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: 12420 Comm: kworker/u8:60 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
Workqueue: events_unbound cfg80211_wiphy_work
RIP: 0010:write_comp_data+0x0/0x90 kernel/kcov.c:240
Code: 48 8b 05 bb 03 e5 11 48 8b 80 70 16 00 00 c3 cc cc cc cc 0f 1f 80 00 00 00 00 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 <49> 89 d2 49 89 f8 49 89 f1 65 48 8b 15 87 03 e5 11 65 8b 05 98 03
RSP: 0018:ffffc900047cf080 EFLAGS: 00000286
RAX: 0000000000000000 RBX: ffff8880d52fcf00 RCX: ffffffff816dd3cc
RDX: ffff8880d52fcf00 RSI: ffff8880552fcf00 RDI: 0000000000000006
RBP: ffff8880552fcf00 R08: 0000000000000001 R09: 0000000000000001
R10: ffffffff908237d7 R11: 0000000000000001 R12: 0000000000000000
R13: ffff888055811800 R14: ffff888055811800 R15: ffffc900047cf300
FS:  0000000000000000(0000) GS:ffff888124af6000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f1ff5fb6ad8 CR3: 0000000032733000 CR4: 00000000003526f0
Call Trace:
 <TASK>
 __virt_addr_valid+0x2c/0x610 arch/x86/mm/physaddr.c:52
 kasan_addr_to_slab+0xd/0x80 mm/kasan/common.c:46
 kasan_record_aux_stack+0xe/0xc0 mm/kasan/generic.c:544
 kvfree_call_rcu+0x86/0x520 mm/slab_common.c:1995
 cfg80211_update_known_bss+0x4f3/0x1300 net/wireless/scan.c:1944
 __cfg80211_bss_update+0x1b7/0x23c0 net/wireless/scan.c:1989
 cfg80211_inform_single_bss_data+0x7ba/0x1df0 net/wireless/scan.c:2381
 cfg80211_inform_bss_data+0x22b/0x3be0 net/wireless/scan.c:3240
 cfg80211_inform_bss_frame_data+0x26f/0x750 net/wireless/scan.c:3331
 ieee80211_bss_info_update+0x310/0xab0 net/mac80211/scan.c:226
 ieee80211_rx_bss_info net/mac80211/ibss.c:1094 [inline]
 ieee80211_rx_mgmt_probe_beacon net/mac80211/ibss.c:1573 [inline]
 ieee80211_ibss_rx_queued_mgmt+0x191b/0x2fe0 net/mac80211/ibss.c:1600
 ieee80211_iface_process_skb net/mac80211/iface.c:1702 [inline]
 ieee80211_iface_work+0xe2e/0x1360 net/mac80211/iface.c:1756
 cfg80211_wiphy_work+0x2c7/0x580 net/wireless/core.c:435
 process_one_work+0x9cf/0x1b70 kernel/workqueue.c:3263
 process_scheduled_works kernel/workqueue.c:3346 [inline]
 worker_thread+0x6c8/0xf10 kernel/workqueue.c:3427
 kthread+0x3c5/0x780 kernel/kthread.c:463
 ret_from_fork+0x675/0x7d0 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>