syzbot

rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	Tasks blocked on level-0 rcu_node (CPUs 0-1): P12195/1:b..l
rcu: 	(detected by 0, t=10502 jiffies, g=64097, q=406 ncpus=2)
task:syz.8.1094      state:R  running task     stack:26160 pid:12195 tgid:12193 ppid:10461  task_flags:0x400040 flags:0x00080002
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5290 [inline]
 __schedule+0x14db/0x5030 kernel/sched/core.c:6902
 preempt_schedule_irq+0x4d/0xa0 kernel/sched/core.c:7229
 irqentry_exit+0x5e3/0x670 kernel/entry/common.c:216
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:697
RIP: 0010:bytes_is_nonzero mm/kasan/generic.c:98 [inline]
RIP: 0010:memory_is_nonzero mm/kasan/generic.c:115 [inline]
RIP: 0010:memory_is_poisoned_n mm/kasan/generic.c:140 [inline]
RIP: 0010:memory_is_poisoned mm/kasan/generic.c:172 [inline]
RIP: 0010:check_region_inline mm/kasan/generic.c:191 [inline]
RIP: 0010:kasan_check_range+0x9f/0x2c0 mm/kasan/generic.c:200
Code: 00 fc ff df 4d 8d 34 19 4d 89 f4 4d 29 dc 49 83 fc 10 7f 29 4d 85 e4 0f 84 41 01 00 00 4c 89 cb 48 f7 d3 4c 01 fb 41 80 3b 00 <0f> 85 de 01 00 00 49 ff c3 48 ff c3 75 ee e9 21 01 00 00 44 89 dd
RSP: 0018:ffffc9000461f100 EFLAGS: 00000246
RAX: ffffc9000461f601 RBX: ffffffffffffffff RCX: ffffffff817468ce
RDX: 0000000000000001 RSI: 0000000000000010 RDI: ffffc9000461f278
RBP: 0000000000000000 R08: ffffc9000461f287 R09: 1ffff920008c3e50
R10: dffffc0000000000 R11: fffff520008c3e50 R12: 0000000000000002
R13: 1ffff920008c3e47 R14: fffff520008c3e51 R15: 1ffff920008c3e4f
 __asan_memset+0x22/0x50 mm/kasan/shadow.c:84
 unwind_next_frame+0xeae/0x23d0 arch/x86/kernel/unwind_orc.c:607
 arch_stack_walk+0x11c/0x150 arch/x86/kernel/stacktrace.c:25
 stack_trace_save+0x9c/0xe0 kernel/stacktrace.c:122
 kasan_save_stack mm/kasan/common.c:57 [inline]
 kasan_save_track+0x3e/0x80 mm/kasan/common.c:78
 poison_kmalloc_redzone mm/kasan/common.c:398 [inline]
 __kasan_kmalloc+0x93/0xb0 mm/kasan/common.c:415
 kasan_kmalloc include/linux/kasan.h:263 [inline]
 __do_kmalloc_node mm/slub.c:5894 [inline]
 __kmalloc_node_track_caller_noprof+0x575/0x820 mm/slub.c:6005
 kmalloc_reserve+0x136/0x290 net/core/skbuff.c:625
 __alloc_skb+0x204/0x3b0 net/core/skbuff.c:707
 alloc_skb include/linux/skbuff.h:1383 [inline]
 _sctp_make_chunk+0x59/0x290 net/sctp/sm_make_chunk.c:1435
 sctp_make_data net/sctp/sm_make_chunk.c:1467 [inline]
 sctp_make_datafrag_empty+0x122/0x230 net/sctp/sm_make_chunk.c:732
 sctp_datamsg_from_user+0x729/0xef0 net/sctp/chunk.c:263
 sctp_sendmsg_to_asoc+0x1059/0x18d0 net/sctp/socket.c:1858
 sctp_sendmsg+0x1941/0x2840 net/sctp/socket.c:2030
 sock_sendmsg_nosec+0x128/0x1d0 net/socket.c:737
 __sock_sendmsg net/socket.c:752 [inline]
 __sys_sendto+0x3ce/0x540 net/socket.c:2221
 __do_sys_sendto net/socket.c:2228 [inline]
 __se_sys_sendto net/socket.c:2224 [inline]
 __x64_sys_sendto+0xde/0x100 net/socket.c:2224
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xec/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f837b38f749
RSP: 002b:00007f837c1ff038 EFLAGS: 00000246 ORIG_RAX: 000000000000002c
RAX: ffffffffffffffda RBX: 00007f837b5e6090 RCX: 00007f837b38f749
RDX: 0000000000034000 RSI: 0000200000847fff RDI: 0000000000000003
RBP: 00007f837b413f91 R08: 000020000005ffe4 R09: 000000000000001c
R10: 00000000000000e0 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f837b5e6128 R14: 00007f837b5e6090 R15: 00007ffe2d757148
 </TASK>
rcu: rcu_preempt kthread starved for 10472 jiffies! g64097 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x0 ->cpu=1
rcu: 	Unless rcu_preempt kthread gets sufficient CPU time, OOM is now expected behavior.
rcu: RCU grace-period kthread stack dump:
task:rcu_preempt     state:R  running task     stack:27456 pid:16    tgid:16    ppid:2      task_flags:0x208040 flags:0x00080000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5290 [inline]
 __schedule+0x14db/0x5030 kernel/sched/core.c:6902
 __schedule_loop kernel/sched/core.c:6984 [inline]
 schedule+0x165/0x360 kernel/sched/core.c:6999
 schedule_timeout+0x12b/0x270 kernel/time/sleep_timeout.c:99
 rcu_gp_fqs_loop+0x301/0x11b0 kernel/rcu/tree.c:2095
 rcu_gp_kthread+0x9b/0x2d0 kernel/rcu/tree.c:2297
 kthread+0x389/0x480 kernel/kthread.c:467
 ret_from_fork+0x510/0xa50 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>
rcu: Stack dump where RCU GP kthread last ran:
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 UID: 0 PID: 9632 Comm: udevd Tainted: G             L      syzkaller #0 PREEMPT(full) 
Tainted: [L]=SOFTLOCKUP
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
RIP: 0010:csd_lock_wait kernel/smp.c:342 [inline]
RIP: 0010:smp_call_function_many_cond+0xcc5/0x1260 kernel/smp.c:877
Code: 45 8b 2c 24 44 89 ee 83 e6 01 31 ff e8 b4 9a 0b 00 41 83 e5 01 49 bd 00 00 00 00 00 fc ff df 75 07 e8 5f 96 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 43 96
RSP: 0018:ffffc90013c17240 EFLAGS: 00000293
RAX: ffffffff81b5835d RBX: 1ffff110170c85c1 RCX: ffff8880321fdac0
RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000000
RBP: ffffc90013c17378 R08: ffffffff8fa2d9f7 R09: 1ffffffff1f45b3e
R10: dffffc0000000000 R11: fffffbfff1f45b3f R12: ffff8880b8642e08
R13: dffffc0000000000 R14: ffff8880b873bd80 R15: 0000000000000000
FS:  00007f42157b6880(0000) GS:ffff888125cf9000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000055b84883ad80 CR3: 00000000746ea000 CR4: 00000000003526f0
Call Trace:
 <TASK>
 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+0x5db/0x1100 arch/x86/mm/tlb.c:1472
 flush_tlb_batched_pending+0x8a/0xe0 mm/rmap.c:808
 zap_pte_range mm/memory.c:1844 [inline]
 zap_pmd_range mm/memory.c:1946 [inline]
 zap_pud_range mm/memory.c:1975 [inline]
 zap_p4d_range mm/memory.c:1996 [inline]
 unmap_page_range+0xc0d/0x4170 mm/memory.c:2017
 unmap_single_vma mm/memory.c:2059 [inline]
 unmap_vmas+0x399/0x580 mm/memory.c:2101
 vms_clear_ptes+0x353/0x530 mm/vma.c:1271
 vms_complete_munmap_vmas+0x206/0x8a0 mm/vma.c:1320
 do_vmi_align_munmap+0x364/0x440 mm/vma.c:1579
 do_vmi_munmap+0x253/0x2e0 mm/vma.c:1627
 __vm_munmap+0x207/0x380 mm/vma.c:3247
 __do_sys_munmap mm/mmap.c:1077 [inline]
 __se_sys_munmap mm/mmap.c:1074 [inline]
 __x64_sys_munmap+0x60/0x70 mm/mmap.c:1074
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xec/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f421511e097
Code: 73 01 c3 48 8b 0d 61 2d 0d 00 f7 d8 64 89 01 48 83 c8 ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 b8 0b 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 8b 0d 31 2d 0d 00 f7 d8 64 89 01 48
RSP: 002b:00007ffd246c87f8 EFLAGS: 00000206 ORIG_RAX: 000000000000000b
RAX: ffffffffffffffda RBX: 000055b848807bf0 RCX: 00007f421511e097
RDX: 0000000000000000 RSI: 00000000009480e8 RDI: 00007f4214600000
RBP: 000055b848807910 R08: 000055b84881a140 R09: 0000000000000006
R10: 0000000000000000 R11: 0000000000000206 R12: 000055b82bbc0588
R13: 00007ffd246c8880 R14: 0000000000000000 R15: 0000000000000000
 </TASK>