watchdog: BUG: soft lockup - CPU#0 stuck for 123s! [syz.2.4457:21314] Modules linked in: irq event stamp: 13083077 hardirqs last enabled at (13083076): [] irqentry_exit+0x59c/0x620 kernel/entry/common.c:219 hardirqs last disabled at (13083077): [] sysvec_apic_timer_interrupt+0xe/0xc0 arch/x86/kernel/apic/apic.c:1056 softirqs last enabled at (283148): [] __do_softirq kernel/softirq.c:656 [inline] softirqs last enabled at (283148): [] invoke_softirq kernel/softirq.c:496 [inline] softirqs last enabled at (283148): [] __irq_exit_rcu+0x5f/0x150 kernel/softirq.c:723 softirqs last disabled at (283151): [] __do_softirq kernel/softirq.c:656 [inline] softirqs last disabled at (283151): [] invoke_softirq kernel/softirq.c:496 [inline] softirqs last disabled at (283151): [] __irq_exit_rcu+0x5f/0x150 kernel/softirq.c:723 CPU: 0 UID: 0 PID: 21314 Comm: syz.2.4457 Not tainted syzkaller #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/24/2026 RIP: 0010:unwind_next_frame+0x484/0x23c0 arch/x86/kernel/unwind_orc.c:520 Code: d2 84 c0 48 0f 45 d1 48 89 15 88 5c 83 11 48 85 d2 0f 84 40 02 00 00 4c 8d 62 04 4c 8d 6a 05 4c 89 e0 48 c1 e8 03 0f b6 04 28 <84> c0 0f 85 66 18 00 00 4c 89 e8 48 c1 e8 03 0f b6 04 28 84 c0 0f RSP: 0018:ffffc900000074d8 EFLAGS: 00000a02 RAX: 0000000000000000 RBX: ffffffff90104f14 RCX: ffffffff90104f18 RDX: ffffffff9090306c RSI: ffffffff90903048 RDI: ffffffff8c073c20 RBP: dffffc0000000000 R08: 000000000000000f R09: ffffffff8e55a3a0 R10: dffffc0000000000 R11: ffffffff81afb200 R12: ffffffff90903070 R13: ffffffff90903071 R14: ffffc900000075a8 R15: ffffffff90104f14 FS: 00007f26214456c0(0000) GS:ffff8881256f7000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000200000001f40 CR3: 00000000687f0000 CR4: 00000000003526f0 DR0: 0000000000000000 DR1: 0000200000000300 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000600 Call Trace: 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:2540 [inline] slab_free mm/slub.c:6670 [inline] kmem_cache_free+0x195/0x610 mm/slub.c:6781 skb_kfree_head net/core/skbuff.c:1066 [inline] skb_free_head net/core/skbuff.c:1080 [inline] skb_release_data+0x688/0x8e0 net/core/skbuff.c:1107 skb_release_all net/core/skbuff.c:1182 [inline] __kfree_skb+0x5d/0x210 net/core/skbuff.c:1196 tcp_write_queue_purge+0x143/0x360 net/ipv4/tcp.c:3338 tcp_done_with_error+0x43/0xd0 net/ipv4/tcp_input.c:4640 tcp_write_err net/ipv4/tcp_timer.c:77 [inline] tcp_write_timeout net/ipv4/tcp_timer.c:294 [inline] tcp_retransmit_timer+0x1ea2/0x3590 net/ipv4/tcp_timer.c:600 tcp_write_timer+0x15c/0x2d0 net/ipv4/tcp_timer.c:736 call_timer_fn+0x192/0x5a0 kernel/time/timer.c:1748 expire_timers kernel/time/timer.c:1799 [inline] __run_timers kernel/time/timer.c:2373 [inline] __run_timer_base+0x652/0x8b0 kernel/time/timer.c:2385 run_timer_base kernel/time/timer.c:2394 [inline] run_timer_softirq+0xb7/0x170 kernel/time/timer.c:2404 handle_softirqs+0x22a/0x7c0 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:preempt_schedule_irq+0x48/0xa0 kernel/sched/core.c:7190 Code: 49 be 00 00 00 00 00 fc ff df eb 09 48 f7 03 10 00 00 00 74 53 bf 01 00 00 00 e8 f3 63 fa f5 e8 3e e0 33 f6 fb bf 01 00 00 00 43 a9 ff ff 9c 58 fa a9 00 02 00 00 74 05 e8 c4 e1 33 f6 bf 01 RSP: 0018:ffffc900052bf810 EFLAGS: 00000202 RAX: 000000000004520d RBX: 0000000000000000 RCX: 0000000000000001 RDX: 0000000000000007 RSI: ffffffff8dccc94a RDI: 0000000000000001 RBP: 0000000000000000 R08: ffffffff8fef0077 R09: 1ffffffff1fde00e R10: dffffc0000000000 R11: fffffbfff1fde00f R12: 0000000000000000 R13: 0000000000000000 R14: dffffc0000000000 R15: 0000000000000000 irqentry_exit+0x597/0x620 kernel/entry/common.c:216 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:697 RIP: 0010:__get_pfnblock_flags_mask+0x1/0x240 mm/page_alloc.c:397 Code: b8 05 00 00 00 0f 42 c1 e9 3c 76 7b 09 cc 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 55 <41> 57 41 56 41 55 41 54 53 50 49 89 d5 49 89 f6 49 89 ff 48 bd 00 RSP: 0018:ffffc900052bf938 EFLAGS: 00000282 RAX: 0000000000000780 RBX: ffffea0000d09800 RCX: dffffc0000000000 RDX: 0000000000000017 RSI: 0000000000034260 RDI: ffffea0000d09800 RBP: 0000000000000003 R08: dffffc0000000000 R09: 0000000000000000 R10: ffffed100684c000 R11: fffffbfff1fde00f R12: 0000000000000001 R13: ff000fffffffffff R14: ffff88813fffbb80 R15: 0000000000000000 get_pfnblock_migratetype mm/page_alloc.c:450 [inline] __free_frozen_pages+0x613/0xd70 mm/page_alloc.c:2954 discard_slab mm/slub.c:3346 [inline] __put_partials+0x146/0x170 mm/slub.c:3886 __slab_free+0x294/0x320 mm/slub.c:5952 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:4953 [inline] slab_alloc_node mm/slub.c:5263 [inline] kmem_cache_alloc_noprof+0x370/0x6e0 mm/slub.c:5270 alloc_empty_file+0x55/0x1d0 fs/file_table.c:237 alloc_file fs/file_table.c:354 [inline] alloc_file_pseudo+0x155/0x240 fs/file_table.c:383 __anon_inode_getfile fs/anon_inodes.c:166 [inline] anon_inode_getfile+0xc5/0x1a0 fs/anon_inodes.c:204 __do_sys_perf_event_open kernel/events/core.c:13760 [inline] __se_sys_perf_event_open+0xf05/0x1d60 kernel/events/core.c:13462 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xe2/0xf80 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f262059bf79 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:00007f2621445028 EFLAGS: 00000246 ORIG_RAX: 000000000000012a RAX: ffffffffffffffda RBX: 00007f2620816090 RCX: 00007f262059bf79 RDX: ffffffffffffffff RSI: 0000000000000000 RDI: 0000200000000640 RBP: 00007f26206327e0 R08: 0000000000000002 R09: 0000000000000000 R10: ffffffffffffffff R11: 0000000000000246 R12: 0000000000000000 R13: 00007f2620816128 R14: 00007f2620816090 R15: 00007fff8851f8b8 Sending NMI from CPU 0 to CPUs 1: NMI backtrace for cpu 1 CPU: 1 UID: 0 PID: 14917 Comm: kworker/u8:19 Not tainted syzkaller #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/24/2026 Workqueue: writeback wb_workfn (flush-8:0) RIP: 0010:csd_lock_wait kernel/smp.c:342 [inline] RIP: 0010:smp_call_function_many_cond+0xce5/0x1270 kernel/smp.c:877 Code: 45 8b 2c 24 44 89 ee 83 e6 01 31 ff e8 c4 db 0b 00 41 83 e5 01 49 bd 00 00 00 00 00 fc ff df 75 07 e8 6f d7 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 53 d7 RSP: 0018:ffffc90004b261e0 EFLAGS: 00000293 RAX: ffffffff81b89f1d RBX: 1ffff110170c856d RCX: ffff888031ae9e80 RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000000 RBP: ffffc90004b26310 R08: ffff88807d52d507 R09: 1ffff1100faa5aa0 R10: dffffc0000000000 R11: ffffffff817784a0 R12: ffff8880b8642b68 R13: dffffc0000000000 R14: ffff8880b873bb00 R15: 0000000000000000 FS: 0000000000000000(0000) GS:ffff8881257f7000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00005555698bb4e8 CR3: 000000005dcf6000 CR4: 00000000003526f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 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:91 [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:324 [inline] ptep_clear_flush+0x120/0x170 mm/pgtable-generic.c:103 page_vma_mkclean_one+0x415/0x790 mm/rmap.c:1017 page_mkclean_one+0x1d8/0x2b0 mm/rmap.c:1065 __rmap_walk_file+0x467/0x620 mm/rmap.c:2927 rmap_walk mm/rmap.c:2971 [inline] folio_mkclean+0x2bb/0x3d0 mm/rmap.c:1097 folio_clear_dirty_for_io+0x1a5/0x710 mm/page-writeback.c:2932 mpage_submit_folio+0x86/0x2b0 fs/ext4/inode.c:2068 mpage_process_page_bufs+0x6d5/0x8e0 fs/ext4/inode.c:2198 mpage_prepare_extent_to_map+0xe1b/0x16f0 fs/ext4/inode.c:2737 ext4_do_writepages+0xbac/0x4600 fs/ext4/inode.c:2878 ext4_writepages+0x241/0x3b0 fs/ext4/inode.c:3026 do_writepages+0x32e/0x550 mm/page-writeback.c:2598 __writeback_single_inode+0x133/0x1230 fs/fs-writeback.c:1737 writeback_sb_inodes+0x92e/0x1940 fs/fs-writeback.c:2030 __writeback_inodes_wb+0x111/0x240 fs/fs-writeback.c:2107 wb_writeback+0x459/0xad0 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+0xaee/0xef0 fs/fs-writeback.c:2403 process_one_work kernel/workqueue.c:3257 [inline] process_scheduled_works+0xaec/0x17a0 kernel/workqueue.c:3340 worker_thread+0xda6/0x1360 kernel/workqueue.c:3421 kthread+0x726/0x8b0 kernel/kthread.c:463 ret_from_fork+0x51b/0xa40 arch/x86/kernel/process.c:158 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:246