syzbot

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BUG: KCSAN: data-race in hrtimer_interrupt / print_cpu

write to 0xffff888237c1b8a0 of 8 bytes by interrupt on cpu 0:
 hrtimer_interrupt+0x1ee/0x810 kernel/time/hrtimer.c:1903
 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1045 [inline]
 __sysvec_apic_timer_interrupt+0x5f/0x1f0 arch/x86/kernel/apic/apic.c:1062
 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1056 [inline]
 sysvec_apic_timer_interrupt+0x32/0x80 arch/x86/kernel/apic/apic.c:1056
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:697
 __sanitizer_cov_trace_pc+0x8/0x70 kernel/kcov.c:213
 tcp_count_delivered net/ipv4/tcp_input.c:487 [inline]
 tcp_clean_rtx_queue net/ipv4/tcp_input.c:3663 [inline]
 tcp_ack+0x14fd/0x3bc0 net/ipv4/tcp_input.c:4366
 tcp_rcv_established+0x4ed/0x12f0 net/ipv4/tcp_input.c:6709
 tcp_v4_do_rcv+0x91d/0xa30 net/ipv4/tcp_ipv4.c:1886
 tcp_v4_rcv+0x19f8/0x1db0 net/ipv4/tcp_ipv4.c:2321
 ip_protocol_deliver_rcu+0x395/0x790 net/ipv4/ip_input.c:207
 ip_local_deliver_finish+0x1fc/0x2f0 net/ipv4/ip_input.c:241
 NF_HOOK include/linux/netfilter.h:318 [inline]
 ip_local_deliver+0xe8/0x1e0 net/ipv4/ip_input.c:262
 dst_input include/net/dst.h:480 [inline]
 ip_sublist_rcv_finish net/ipv4/ip_input.c:584 [inline]
 ip_list_rcv_finish net/ipv4/ip_input.c:636 [inline]
 ip_sublist_rcv+0x5ce/0x6d0 net/ipv4/ip_input.c:644
 ip_list_rcv+0x261/0x290 net/ipv4/ip_input.c:678
 __netif_receive_skb_list_ptype net/core/dev.c:6210 [inline]
 __netif_receive_skb_list_core+0x4dc/0x500 net/core/dev.c:6257
 __netif_receive_skb_list net/core/dev.c:6309 [inline]
 netif_receive_skb_list_internal+0x47d/0x5f0 net/core/dev.c:6400
 gro_normal_list include/net/gro.h:523 [inline]
 gro_flush_normal include/net/gro.h:531 [inline]
 napi_complete_done+0x19c/0x3f0 net/core/dev.c:6768
 virtqueue_napi_complete drivers/net/virtio_net.c:749 [inline]
 virtnet_poll+0x1bfb/0x2080 drivers/net/virtio_net.c:3091
 __napi_poll+0x61/0x330 net/core/dev.c:7695
 napi_poll net/core/dev.c:7758 [inline]
 net_rx_action+0x452/0x930 net/core/dev.c:7910
 handle_softirqs+0xb9/0x2a0 kernel/softirq.c:622
 __do_softirq kernel/softirq.c:656 [inline]
 invoke_softirq kernel/softirq.c:496 [inline]
 __irq_exit_rcu+0x39/0xc0 kernel/softirq.c:723
 common_interrupt+0x83/0x90 arch/x86/kernel/irq.c:326
 asm_common_interrupt+0x26/0x40 arch/x86/include/asm/idtentry.h:688
 clear_pages arch/x86/include/asm/page_64.h:103 [inline]
 clear_page arch/x86/include/asm/page_64.h:114 [inline]
 clear_highpage_kasan_tagged include/linux/highmem.h:344 [inline]
 kernel_init_pages mm/page_alloc.c:1265 [inline]
 post_alloc_hook mm/page_alloc.c:1887 [inline]
 prep_new_page mm/page_alloc.c:1897 [inline]
 get_page_from_freelist+0x18a5/0x1aa0 mm/page_alloc.c:3962
 __alloc_frozen_pages_noprof+0x161/0x360 mm/page_alloc.c:5250
 alloc_pages_mpol+0xb3/0x260 mm/mempolicy.c:2484
 alloc_frozen_pages_noprof mm/mempolicy.c:2555 [inline]
 alloc_pages_noprof+0x8f/0x130 mm/mempolicy.c:2575
 vm_area_alloc_pages mm/vmalloc.c:3662 [inline]
 __vmalloc_area_node mm/vmalloc.c:3876 [inline]
 __vmalloc_node_range_noprof+0x599/0x12b0 mm/vmalloc.c:4064
 __kvmalloc_node_noprof+0x3d4/0x650 mm/slub.c:6758
 futex_hash_allocate+0x190/0x9d0 kernel/futex/core.c:1812
 futex_hash_prctl+0xd8/0xf0 kernel/futex/core.c:1958
 __do_sys_prctl kernel/sys.c:2884 [inline]
 __se_sys_prctl+0xa3d/0x13f0 kernel/sys.c:2533
 __x64_sys_prctl+0x67/0x80 kernel/sys.c:2533
 x64_sys_call+0x2533/0x3020 arch/x86/include/generated/asm/syscalls_64.h:158
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x12c/0x370 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff888237c1b8a0 of 8 bytes by task 8294 on cpu 1:
 print_cpu+0x2ea/0x660 kernel/time/timer_list.c:131
 timer_list_show+0x107/0x170 kernel/time/timer_list.c:293
 seq_read_iter+0x636/0x940 fs/seq_file.c:273
 proc_reg_read_iter+0x110/0x180 fs/proc/inode.c:299
 copy_splice_read+0x471/0x6c0 fs/splice.c:362
 do_splice_read fs/splice.c:980 [inline]
 splice_direct_to_actor+0x26e/0x670 fs/splice.c:1084
 do_splice_direct_actor fs/splice.c:1202 [inline]
 do_splice_direct+0x119/0x1a0 fs/splice.c:1228
 do_sendfile+0x382/0x650 fs/read_write.c:1372
 __do_sys_sendfile64 fs/read_write.c:1433 [inline]
 __se_sys_sendfile64 fs/read_write.c:1419 [inline]
 __x64_sys_sendfile64+0x105/0x150 fs/read_write.c:1419
 x64_sys_call+0x2dc4/0x3020 arch/x86/include/generated/asm/syscalls_64.h:41
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x12c/0x370 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x0000003a10878582 -> 0x7fffffffffffffff

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 8294 Comm: syz.0.1083 Tainted: G        W           syzkaller #0 PREEMPT(full) 
Tainted: [W]=WARN
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026
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