syzbot

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BUG: KCSAN: data-race in hrtimer_interrupt / print_cpu

write to 0xffff888237c1b260 of 8 bytes by interrupt on cpu 0:
 hrtimer_interrupt+0x193/0x460 kernel/time/hrtimer.c:1879
 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1039 [inline]
 __sysvec_apic_timer_interrupt+0x5c/0x1d0 arch/x86/kernel/apic/apic.c:1056
 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1050 [inline]
 sysvec_apic_timer_interrupt+0x6f/0x80 arch/x86/kernel/apic/apic.c:1050
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:702
 arch_atomic64_read arch/x86/include/asm/atomic64_64.h:15 [inline]
 raw_atomic64_read include/linux/atomic/atomic-arch-fallback.h:2583 [inline]
 raw_atomic_long_read include/linux/atomic/atomic-long.h:38 [inline]
 atomic_long_read include/linux/atomic/atomic-instrumented.h:3189 [inline]
 find_watchpoint kernel/kcsan/core.c:131 [inline]
 check_access kernel/kcsan/core.c:737 [inline]
 __tsan_read4+0x2c/0x190 kernel/kcsan/core.c:1024
 rb_event_data kernel/trace/ring_buffer.c:292 [inline]
 ring_buffer_event_data+0x1a/0xa0 kernel/trace/ring_buffer.c:308
 trace_event_setup kernel/trace/trace.c:1068 [inline]
 __trace_buffer_lock_reserve kernel/trace/trace.c:1083 [inline]
 trace_event_buffer_lock_reserve+0x15d/0x300 kernel/trace/trace.c:2799
 trace_event_buffer_reserve+0x154/0x1d0 kernel/trace/trace_events.c:672
 do_trace_event_raw_event_bpf_trace_printk kernel/trace/bpf_trace.h:11 [inline]
 trace_event_raw_event_bpf_trace_printk+0x95/0x160 kernel/trace/bpf_trace.h:11
 __do_trace_bpf_trace_printk kernel/trace/bpf_trace.h:11 [inline]
 trace_bpf_trace_printk kernel/trace/bpf_trace.h:11 [inline]
 ____bpf_trace_printk kernel/trace/bpf_trace.c:380 [inline]
 bpf_trace_printk+0x168/0x1c0 kernel/trace/bpf_trace.c:363
 bpf_prog_7288d49156658ef5+0x40/0x6c
 bpf_dispatcher_nop_func include/linux/bpf.h:1332 [inline]
 __bpf_prog_run include/linux/filter.h:718 [inline]
 bpf_prog_run include/linux/filter.h:725 [inline]
 __bpf_trace_run kernel/trace/bpf_trace.c:2257 [inline]
 bpf_trace_run2+0x107/0x1c0 kernel/trace/bpf_trace.c:2298
 __do_trace_kfree include/trace/events/kmem.h:94 [inline]
 trace_kfree include/trace/events/kmem.h:94 [inline]
 kfree+0x27b/0x320 mm/slub.c:4881
 nsim_fib_event_work+0x1436/0x21a0 drivers/net/netdevsim/fib.c:1495
 process_one_work kernel/workqueue.c:3236 [inline]
 process_scheduled_works+0x4cb/0x9d0 kernel/workqueue.c:3319
 worker_thread+0x582/0x770 kernel/workqueue.c:3400
 kthread+0x489/0x510 kernel/kthread.c:463
 ret_from_fork+0x11f/0x1b0 arch/x86/kernel/process.c:148
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

read to 0xffff888237c1b260 of 8 bytes by task 6161 on cpu 1:
 print_cpu+0x30b/0x680 kernel/time/timer_list.c:133
 timer_list_show+0x107/0x170 kernel/time/timer_list.c:295
 seq_read_iter+0x319/0x940 fs/seq_file.c:230
 proc_reg_read_iter+0x110/0x180 fs/proc/inode.c:299
 io_iter_do_read io_uring/rw.c:828 [inline]
 __io_read+0x438/0xc20 io_uring/rw.c:944
 io_read+0x1c/0x60 io_uring/rw.c:1023
 __io_issue_sqe+0xfe/0x2e0 io_uring/io_uring.c:1773
 io_issue_sqe+0x53/0x970 io_uring/io_uring.c:1796
 io_queue_sqe io_uring/io_uring.c:2025 [inline]
 io_submit_sqe io_uring/io_uring.c:2285 [inline]
 io_submit_sqes+0x675/0x1060 io_uring/io_uring.c:2398
 __do_sys_io_uring_enter io_uring/io_uring.c:3465 [inline]
 __se_sys_io_uring_enter+0x1c1/0x1b70 io_uring/io_uring.c:3399
 __x64_sys_io_uring_enter+0x78/0x90 io_uring/io_uring.c:3399
 x64_sys_call+0x2de1/0x2ff0 arch/x86/include/generated/asm/syscalls_64.h:427
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xd2/0x200 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x00000012fafc9453 -> 0x00000012fb27dcf1

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 6161 Comm: syz.2.1017 Not tainted syzkaller #0 PREEMPT(voluntary) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025
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