INFO: task syz.1.9148:21996 blocked for more than 143 seconds. Tainted: G L syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. task:syz.1.9148 state:D stack:28072 pid:21996 tgid:21995 ppid:14191 task_flags:0x400040 flags:0x00080002 Call Trace: context_switch kernel/sched/core.c:5298 [inline] __schedule+0x1553/0x5240 kernel/sched/core.c:6911 __schedule_loop kernel/sched/core.c:6993 [inline] rt_mutex_schedule+0x76/0xf0 kernel/sched/core.c:7289 rt_mutex_slowlock_block+0x508/0x680 kernel/locking/rtmutex.c:1647 __rt_mutex_slowlock kernel/locking/rtmutex.c:1721 [inline] __rt_mutex_slowlock_locked kernel/locking/rtmutex.c:1760 [inline] rt_mutex_slowlock+0x2dc/0x7b0 kernel/locking/rtmutex.c:1800 __rt_mutex_lock kernel/locking/rtmutex.c:1815 [inline] __mutex_lock_common kernel/locking/rtmutex_api.c:534 [inline] mutex_lock_nested+0x168/0x1d0 kernel/locking/rtmutex_api.c:552 bdev_open+0xe0/0xcc0 block/bdev.c:961 blkdev_open+0x485/0x620 block/fops.c:697 do_dentry_open+0x83d/0x13e0 fs/open.c:949 vfs_open+0x3b/0x350 fs/open.c:1081 do_open fs/namei.c:4677 [inline] path_openat+0x2e43/0x38a0 fs/namei.c:4836 do_file_open+0x23e/0x4a0 fs/namei.c:4865 do_sys_openat2+0x113/0x200 fs/open.c:1366 do_sys_open fs/open.c:1372 [inline] __do_sys_openat fs/open.c:1388 [inline] __se_sys_openat fs/open.c:1383 [inline] __x64_sys_openat+0x138/0x170 fs/open.c:1383 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x14d/0xf80 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f70acccd04e RSP: 002b:00007f70aaf65b28 EFLAGS: 00000246 ORIG_RAX: 0000000000000101 RAX: ffffffffffffffda RBX: 00007f70aaf666c0 RCX: 00007f70acccd04e RDX: 00000000000e8082 RSI: 00007f70aaf65c00 RDI: ffffffffffffff9c RBP: 00007f70aaf65c00 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: cccccccccccccccd R13: 00007f70acf86038 R14: 00007f70acf85fa0 R15: 00007ffc5d7d3508 Showing all locks held in the system: 1 lock held by khungtaskd/38: #0: ffffffff8ddcb9c0 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:312 [inline] #0: ffffffff8ddcb9c0 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:850 [inline] #0: ffffffff8ddcb9c0 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x2e/0x180 kernel/locking/lockdep.c:6775 2 locks held by getty/5550: #0: ffff88823bf4c0a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:243 #1: ffffc90003e8b2e0 (&ldata->atomic_read_lock){+.+.}-{4:4}, at: n_tty_read+0x462/0x13c0 drivers/tty/n_tty.c:2211 1 lock held by udevd/14431: #0: ffff888026a974c8 (&disk->open_mutex){+.+.}-{4:4}, at: bdev_open+0xe0/0xcc0 block/bdev.c:961 1 lock held by syz.1.9148/21996: #0: ffff888026a974c8 (&disk->open_mutex){+.+.}-{4:4}, at: bdev_open+0xe0/0xcc0 block/bdev.c:961 ============================================= NMI backtrace for cpu 0 CPU: 0 UID: 0 PID: 38 Comm: khungtaskd Tainted: G L syzkaller #0 PREEMPT_{RT,(full)} Tainted: [L]=SOFTLOCKUP Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/18/2026 Call Trace: dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120 nmi_cpu_backtrace+0x274/0x2d0 lib/nmi_backtrace.c:113 nmi_trigger_cpumask_backtrace+0x17a/0x300 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+0x135/0x170 lib/sys_info.c:165 check_hung_uninterruptible_tasks kernel/hung_task.c:346 [inline] watchdog+0xfd9/0x1030 kernel/hung_task.c:515 kthread+0x388/0x470 kernel/kthread.c:436 ret_from_fork+0x51e/0xb90 arch/x86/kernel/process.c:158 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 Sending NMI from CPU 0 to CPUs 1: NMI backtrace for cpu 1 CPU: 1 UID: 0 PID: 29 Comm: ktimers/1 Tainted: G L syzkaller #0 PREEMPT_{RT,(full)} Tainted: [L]=SOFTLOCKUP Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/18/2026 RIP: 0010:__lock_acquire+0x84d/0x2cf0 kernel/locking/lockdep.c:-1 Code: 00 60 00 00 09 c5 48 89 d8 48 c1 e8 20 29 c5 89 c1 c1 c1 04 31 e9 01 d8 29 cb 89 ca c1 c2 06 31 da 01 c1 29 d0 89 d6 c1 c6 08 <31> c6 01 ca 29 f1 89 f3 c1 c3 10 31 cb 01 d6 29 da 89 dd c1 c5 13 RSP: 0018:ffffc90000a3f158 EFLAGS: 00000082 RAX: 00000000923660c1 RBX: 00000000c5e72f55 RCX: 0000000084e95067 RDX: 000000004c8d45fc RSI: 000000008d45fc4c RDI: ffff88801ceebd00 RBP: 000000008d49724d R08: ffffffff81767e65 R09: ffffffff8ddcb9c0 R10: ffffc90000a3f438 R11: ffffffff81af9290 R12: ffff88801ceec9a8 R13: ffff88801ceec9a8 R14: ffff88801ceebd00 R15: 0000000000000006 FS: 0000000000000000(0000) GS:ffff888126435000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 000056234d2f7168 CR3: 000000000dbba000 CR4: 00000000003526f0 DR0: ffffffffffffffff DR1: 00000000000001f8 DR2: 0000000000080083 DR3: ffffffffefffff16 DR6: 00000000ffff0ff0 DR7: 0000000000000400 Call Trace: lock_acquire+0xf0/0x2e0 kernel/locking/lockdep.c:5868 rcu_lock_acquire include/linux/rcupdate.h:312 [inline] rcu_read_lock include/linux/rcupdate.h:850 [inline] class_rcu_constructor include/linux/rcupdate.h:1193 [inline] unwind_next_frame+0xc2/0x23c0 arch/x86/kernel/unwind_orc.c:495 arch_stack_walk+0x11b/0x150 arch/x86/kernel/stacktrace.c:25 stack_trace_save+0xa9/0x100 kernel/stacktrace.c:122 kasan_save_stack mm/kasan/common.c:57 [inline] kasan_save_track+0x3e/0x80 mm/kasan/common.c:78 unpoison_slab_object mm/kasan/common.c:340 [inline] __kasan_slab_alloc+0x6c/0x80 mm/kasan/common.c:366 kasan_slab_alloc include/linux/kasan.h:253 [inline] slab_post_alloc_hook mm/slub.c:4538 [inline] slab_alloc_node mm/slub.c:4866 [inline] kmem_cache_alloc_node_noprof+0x22a/0x6e0 mm/slub.c:4918 __alloc_skb+0x1d0/0x7d0 net/core/skbuff.c:702 __netdev_alloc_skb+0xc0/0x4b0 net/core/skbuff.c:775 netdev_alloc_skb include/linux/skbuff.h:3485 [inline] dev_alloc_skb include/linux/skbuff.h:3498 [inline] __ieee80211_beacon_get+0xca4/0x1860 net/mac80211/tx.c:5658 ieee80211_beacon_get_tim+0xbd/0x2c0 net/mac80211/tx.c:5780 ieee80211_beacon_get include/net/mac80211.h:5720 [inline] mac80211_hwsim_beacon_tx+0x3c5/0x870 drivers/net/wireless/virtual/mac80211_hwsim.c:2361 __iterate_interfaces+0x2ab/0x590 net/mac80211/util.c:760 ieee80211_iterate_active_interfaces_atomic+0xdb/0x180 net/mac80211/util.c:796 mac80211_hwsim_beacon+0xbb/0x180 drivers/net/wireless/virtual/mac80211_hwsim.c:2395 __run_hrtimer kernel/time/hrtimer.c:1785 [inline] __hrtimer_run_queues+0x55f/0xda0 kernel/time/hrtimer.c:1849 hrtimer_run_softirq+0x192/0x5d0 kernel/time/hrtimer.c:1866 handle_softirqs+0x1de/0x6f0 kernel/softirq.c:622 __do_softirq kernel/softirq.c:656 [inline] run_ktimerd+0x69/0x100 kernel/softirq.c:1138 smpboot_thread_fn+0x541/0xa50 kernel/smpboot.c:160 kthread+0x388/0x470 kernel/kthread.c:436 ret_from_fork+0x51e/0xb90 arch/x86/kernel/process.c:158 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245