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BUG: KCSAN: data-race in hrtimer_interrupt / print_cpu

write to 0xffff88813bc1dea0 of 8 bytes by interrupt on cpu 0:
 hrtimer_interrupt+0x1e2/0xa10 kernel/time/hrtimer.c:1637
 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1085 [inline]
 __sysvec_apic_timer_interrupt+0x6f/0x200 arch/x86/kernel/apic/apic.c:1102
 asm_call_irq_on_stack+0xf/0x20
 __run_sysvec_on_irqstack arch/x86/include/asm/irq_stack.h:37 [inline]
 run_sysvec_on_irqstack_cond arch/x86/include/asm/irq_stack.h:89 [inline]
 sysvec_apic_timer_interrupt+0x52/0x90 arch/x86/kernel/apic/apic.c:1096
 asm_sysvec_apic_timer_interrupt+0x12/0x20 arch/x86/include/asm/idtentry.h:628
 check_access kernel/kcsan/core.c:625 [inline]
 __tsan_read4+0xe9/0x180 kernel/kcsan/core.c:841
 skb_tail_pointer include/linux/skbuff.h:2198 [inline]
 INET_ECN_set_ce include/net/inet_ecn.h:177 [inline]
 ____bpf_skb_ecn_set_ce net/core/filter.c:6423 [inline]
 bpf_skb_ecn_set_ce+0x602/0x830 net/core/filter.c:6402
 bpf_prog_04896ce312478ae6+0x10/0xd8
 bpf_dispatcher_nop_func include/linux/bpf.h:651 [inline]
 bpf_test_run+0x278/0x440 net/bpf/test_run.c:50
 bpf_prog_test_run_skb+0x6f0/0xe70 net/bpf/test_run.c:581
 bpf_prog_test_run kernel/bpf/syscall.c:3120 [inline]
 __do_sys_bpf+0x3a17/0x99c0 kernel/bpf/syscall.c:4398
 __se_sys_bpf kernel/bpf/syscall.c:4338 [inline]
 __x64_sys_bpf+0x3d/0x50 kernel/bpf/syscall.c:4338
 do_syscall_64+0x39/0x80 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

read to 0xffff88813bc1dea0 of 8 bytes by task 12740 on cpu 1:
 print_cpu+0x32e/0x690 kernel/time/timer_list.c:133
 timer_list_show+0x114/0x180 kernel/time/timer_list.c:283
 seq_read_iter+0x5f6/0x8e0 fs/seq_file.c:269
 proc_reg_read_iter+0xfc/0x170 fs/proc/inode.c:310
 call_read_iter include/linux/fs.h:1895 [inline]
 generic_file_splice_read+0x22a/0x310 fs/splice.c:311
 do_splice_to fs/splice.c:788 [inline]
 splice_direct_to_actor+0x2aa/0x650 fs/splice.c:867
 do_splice_direct+0xf5/0x170 fs/splice.c:976
 do_sendfile+0x5db/0xca0 fs/read_write.c:1257
 __do_sys_sendfile64 fs/read_write.c:1318 [inline]
 __se_sys_sendfile64 fs/read_write.c:1304 [inline]
 __x64_sys_sendfile64+0xf2/0x130 fs/read_write.c:1304
 do_syscall_64+0x39/0x80 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 12740 Comm: syz-executor.2 Not tainted 5.11.0-rc2-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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