watchdog: BUG: soft lockup - CPU#0 stuck for 143s! [syz.2.6579:4251] Modules linked in: irq event stamp: 13696819 hardirqs last enabled at (13696818): [] irqentry_exit+0x59e/0x620 kernel/entry/common.c:242 hardirqs last disabled at (13696819): [] sysvec_apic_timer_interrupt+0xe/0xc0 arch/x86/kernel/apic/apic.c:1056 softirqs last enabled at (13491826): [] __do_softirq kernel/softirq.c:656 [inline] softirqs last enabled at (13491826): [] invoke_softirq kernel/softirq.c:496 [inline] softirqs last enabled at (13491826): [] __irq_exit_rcu+0x5f/0x150 kernel/softirq.c:723 softirqs last disabled at (13491829): [] __do_softirq kernel/softirq.c:656 [inline] softirqs last disabled at (13491829): [] invoke_softirq kernel/softirq.c:496 [inline] softirqs last disabled at (13491829): [] __irq_exit_rcu+0x5f/0x150 kernel/softirq.c:723 CPU: 0 UID: 0 PID: 4251 Comm: syz.2.6579 Not tainted syzkaller #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026 RIP: 0010:lock_acquire+0x20b/0x2e0 kernel/locking/lockdep.c:5872 Code: e9 30 ff ff ff e8 35 69 0c 0a f7 c3 00 02 00 00 0f 84 38 ff ff ff 65 48 8b 05 b1 46 7a 11 48 3b 44 24 30 75 33 fb 48 83 c4 38 <5b> 41 5c 41 5d 41 5e 41 5f 5d e9 16 4f 0f 0a cc 48 8d 3d 3e 56 73 RSP: 0018:ffffc900000073b8 EFLAGS: 00000286 RAX: 5df4ec7d5c9b1400 RBX: 0000000000000246 RCX: 0000000000000102 RDX: 000000008eba6367 RSI: ffffffff8e165829 RDI: ffffffff8c27b480 RBP: 0000000000000000 R08: ffffffff81767de5 R09: ffffffff8e75e3e0 R10: ffffc90000007008 R11: ffffffff81b0bfa0 R12: 0000000000000002 R13: ffffffff8e75e3e0 R14: 0000000000000000 R15: 0000000000000000 FS: 00007f4e393c76c0(0000) GS:ffff888125463000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f70e3b4da08 CR3: 0000000032a3a000 CR4: 00000000003526f0 DR0: 0000200000000300 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000200000000300 DR6: 00000000ffff0ff0 DR7: 0000000000000600 Call Trace: 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 kasan_save_free_info+0x46/0x50 mm/kasan/generic.c:584 poison_slab_object mm/kasan/common.c:253 [inline] __kasan_slab_free+0x5c/0x80 mm/kasan/common.c:285 kasan_slab_free include/linux/kasan.h:235 [inline] slab_free_hook mm/slub.c:2692 [inline] slab_free mm/slub.c:6168 [inline] kmem_cache_free+0x187/0x630 mm/slub.c:6298 kfree_skb_reason include/linux/skbuff.h:1322 [inline] kfree_skb include/linux/skbuff.h:1331 [inline] llc_sap_handler+0x1041/0x11c0 net/llc/llc_sap.c:-1 llc_rcv+0x74f/0xd00 net/llc/llc_input.c:212 __netif_receive_skb_one_core net/core/dev.c:6164 [inline] __netif_receive_skb net/core/dev.c:6277 [inline] process_backlog+0xc66/0x1950 net/core/dev.c:6628 __napi_poll+0xae/0x340 net/core/dev.c:7692 napi_poll net/core/dev.c:7755 [inline] net_rx_action+0x627/0xf70 net/core/dev.c:7912 handle_softirqs+0x22a/0x870 kernel/softirq.c:622 __do_softirq kernel/softirq.c:656 [inline] invoke_softirq kernel/softirq.c:496 [inline] __irq_exit_rcu+0x5f/0x150 kernel/softirq.c:723 irq_exit_rcu+0x9/0x30 kernel/softirq.c:739 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1056 [inline] sysvec_apic_timer_interrupt+0xa6/0xc0 arch/x86/kernel/apic/apic.c:1056 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:697 RIP: 0010:perf_trace_run_bpf_submit+0xd/0x170 kernel/events/core.c:11329 Code: ff ff 66 66 2e 0f 1f 84 00 00 00 00 00 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 f3 0f 1e fa 55 41 57 41 56 41 55 41 54 <53> 48 83 ec 10 4d 89 ce 4c 89 44 24 08 49 89 cd 89 d3 89 74 24 04 RSP: 0018:ffffc9000d32e580 EFLAGS: 00000246 RAX: ffffffff8e75e3e0 RBX: ffffe8ffffa7c010 RCX: ffffffff8e62a480 RDX: 0000000000000000 RSI: 000000000000002c RDI: ffffe8ffffa7c000 RBP: ffffc9000d32e6c0 R08: 0000000000000001 R09: ffff8880b8633350 R10: dffffc0000000000 R11: fffff91ffff4f805 R12: dffffc0000000000 R13: dffffc0000000000 R14: 000000000000002c R15: 1ffff92001a65cc0 do_perf_trace_lock include/trace/events/lock.h:50 [inline] perf_trace_lock+0x32d/0x410 include/trace/events/lock.h:50 __do_trace_lock_release include/trace/events/lock.h:69 [inline] trace_lock_release include/trace/events/lock.h:69 [inline] lock_release+0x392/0x3d0 kernel/locking/lockdep.c:5879 rcu_lock_release include/linux/rcupdate.h:322 [inline] rcu_read_unlock include/linux/rcupdate.h:881 [inline] class_rcu_destructor include/linux/rcupdate.h:1193 [inline] unwind_next_frame+0x1aaa/0x23c0 arch/x86/kernel/unwind_orc.c:695 arch_stack_walk+0x11b/0x150 arch/x86/kernel/stacktrace.c:25 stack_trace_save+0xa9/0x100 kernel/stacktrace.c:122 kasan_save_stack+0x3e/0x60 mm/kasan/common.c:57 kasan_record_aux_stack+0xbd/0xd0 mm/kasan/generic.c:556 __call_rcu_common kernel/rcu/tree.c:3131 [inline] call_rcu+0xee/0x890 kernel/rcu/tree.c:3251 context_switch kernel/sched/core.c:5298 [inline] __schedule+0x15e5/0x52d0 kernel/sched/core.c:6908 preempt_schedule_notrace+0x57/0x90 kernel/sched/core.c:7185 preempt_schedule_notrace_thunk+0x16/0x30 arch/x86/entry/thunk.S:13 class_preempt_notrace_destructor include/linux/preempt.h:469 [inline] perf_trace_lock+0x38b/0x410 include/trace/events/lock.h:50 __do_trace_lock_release include/trace/events/lock.h:69 [inline] trace_lock_release include/trace/events/lock.h:69 [inline] lock_release+0x392/0x3d0 kernel/locking/lockdep.c:5879 rcu_lock_release include/linux/rcupdate.h:322 [inline] rcu_read_unlock include/linux/rcupdate.h:881 [inline] class_rcu_destructor include/linux/rcupdate.h:1193 [inline] unwind_next_frame+0x1aaa/0x23c0 arch/x86/kernel/unwind_orc.c:695 arch_stack_walk+0x11b/0x150 arch/x86/kernel/stacktrace.c:25 stack_trace_save+0xa9/0x100 kernel/stacktrace.c:122 save_stack+0x122/0x230 mm/page_owner.c:165 __reset_page_owner+0x71/0x1f0 mm/page_owner.c:320 reset_page_owner include/linux/page_owner.h:25 [inline] __free_pages_prepare mm/page_alloc.c:1433 [inline] __free_frozen_pages+0xc2b/0xdb0 mm/page_alloc.c:2978 __slab_free+0x263/0x2b0 mm/slub.c:5576 qlink_free mm/kasan/quarantine.c:163 [inline] qlist_free_all+0x97/0x100 mm/kasan/quarantine.c:179 kasan_quarantine_reduce+0x148/0x160 mm/kasan/quarantine.c:286 __kasan_slab_alloc+0x22/0x80 mm/kasan/common.c:350 kasan_slab_alloc include/linux/kasan.h:253 [inline] slab_post_alloc_hook mm/slub.c:4542 [inline] slab_alloc_node mm/slub.c:4869 [inline] __kmalloc_cache_noprof+0x2ba/0x660 mm/slub.c:5378 kmalloc_noprof include/linux/slab.h:950 [inline] kzalloc_noprof include/linux/slab.h:1188 [inline] do_check_common+0x159/0x2600 kernel/bpf/verifier.c:24642 do_check_main kernel/bpf/verifier.c:24843 [inline] bpf_check+0x23b2/0x1ccc0 kernel/bpf/verifier.c:26223 bpf_prog_load+0x1484/0x1ae0 kernel/bpf/syscall.c:3089 __sys_bpf+0x618/0x950 kernel/bpf/syscall.c:6228 __do_sys_bpf kernel/bpf/syscall.c:6341 [inline] __se_sys_bpf kernel/bpf/syscall.c:6339 [inline] __x64_sys_bpf+0x7c/0x90 kernel/bpf/syscall.c:6339 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: 0033:0x7f4e3859c799 Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 e8 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007f4e393c7028 EFLAGS: 00000246 ORIG_RAX: 0000000000000141 RAX: ffffffffffffffda RBX: 00007f4e38815fa0 RCX: 00007f4e3859c799 RDX: 0000000000000094 RSI: 0000200000001100 RDI: 0000000000000005 RBP: 00007f4e38632c99 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007f4e38816038 R14: 00007f4e38815fa0 R15: 00007fffd07b4b28 Sending NMI from CPU 0 to CPUs 1: NMI backtrace for cpu 1 CPU: 1 UID: 0 PID: 26114 Comm: kworker/u8:43 Not tainted syzkaller #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026 Workqueue: writeback wb_workfn (flush-8:0) RIP: 0010:csd_lock_wait kernel/smp.c:342 [inline] RIP: 0010:smp_call_function_many_cond+0xce5/0x12c0 kernel/smp.c:877 Code: 45 8b 2c 24 44 89 ee 83 e6 01 31 ff e8 24 e6 0b 00 41 83 e5 01 49 bd 00 00 00 00 00 fc ff df 75 07 e8 cf e1 0b 00 eb 38 f3 90 <42> 0f b6 04 2b 84 c0 75 11 41 f7 04 24 01 00 00 00 74 1e e8 b3 e1 RSP: 0018:ffffc9000ccb6240 EFLAGS: 00000293 RAX: ffffffff81b9bbfd RBX: 1ffff110170c8515 RCX: ffff88808d730000 RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000000 RBP: ffffc9000ccb6370 R08: ffff888051ef3c87 R09: 1ffff1100a3de790 R10: dffffc0000000000 R11: ffffffff817872a0 R12: ffff8880b86428a8 R13: dffffc0000000000 R14: ffff8880b873bf80 R15: 0000000000000000 FS: 0000000000000000(0000) GS:ffff888125563000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00005589c7981a38 CR3: 0000000041bbc000 CR4: 00000000003526f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000200000000300 DR6: 00000000ffff0ff0 DR7: 0000000000000600 Call Trace: on_each_cpu_cond_mask+0x3f/0x80 kernel/smp.c:1043 __flush_tlb_multi arch/x86/include/asm/paravirt.h:57 [inline] flush_tlb_multi arch/x86/mm/tlb.c:1382 [inline] flush_tlb_mm_range+0x5c3/0x10c0 arch/x86/mm/tlb.c:1472 flush_tlb_page arch/x86/include/asm/tlbflush.h:323 [inline] ptep_clear_flush+0x120/0x170 mm/pgtable-generic.c:103 page_vma_mkclean_one+0x438/0x780 mm/rmap.c:1125 page_mkclean_one+0x1d8/0x2b0 mm/rmap.c:1173 __rmap_walk_file+0x467/0x620 mm/rmap.c:3036 rmap_walk mm/rmap.c:3080 [inline] folio_mkclean+0x2bb/0x3d0 mm/rmap.c:1205 folio_clear_dirty_for_io+0x1a5/0x710 mm/page-writeback.c:2888 mpage_submit_folio+0x86/0x2b0 fs/ext4/inode.c:2061 mpage_process_page_bufs+0x6d5/0x8e0 fs/ext4/inode.c:2191 mpage_prepare_extent_to_map+0xe1b/0x16f0 fs/ext4/inode.c:2730 ext4_do_writepages+0xbca/0x46e0 fs/ext4/inode.c:2871 ext4_writepages+0x241/0x3b0 fs/ext4/inode.c:3019 do_writepages+0x32e/0x550 mm/page-writeback.c:2554 __writeback_single_inode+0x133/0x11a0 fs/fs-writeback.c:1750 writeback_sb_inodes+0x992/0x1a20 fs/fs-writeback.c:2042 __writeback_inodes_wb+0x111/0x240 fs/fs-writeback.c:2118 wb_writeback+0x46a/0xb70 fs/fs-writeback.c:2229 wb_check_old_data_flush fs/fs-writeback.c:2333 [inline] wb_do_writeback fs/fs-writeback.c:2386 [inline] wb_workfn+0xb4c/0xf50 fs/fs-writeback.c:2414 process_one_work kernel/workqueue.c:3275 [inline] process_scheduled_works+0xb02/0x1830 kernel/workqueue.c:3358 worker_thread+0xa50/0xfc0 kernel/workqueue.c:3439 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