syzbot

==================================================================
BUG: KCSAN: data-race in hrtimer_interrupt / print_cpu

read-write to 0xffff888237d1b898 of 2 bytes by interrupt on cpu 1:
 hrtimer_interrupt+0x6b9/0x810 kernel/time/hrtimer.c:1944
 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+0x6f/0x80 arch/x86/kernel/apic/apic.c:1056
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:697
 kcsan_setup_watchpoint+0x404/0x410 kernel/kcsan/core.c:705
 perf_poll+0x18d/0x1f0 kernel/events/core.c:6308
 vfs_poll include/linux/poll.h:82 [inline]
 __io_arm_poll_handler+0x1ec/0xc30 io_uring/poll.c:581
 io_arm_apoll+0x2eb/0x430 io_uring/poll.c:689
 io_arm_poll_handler+0x12f/0x160 io_uring/poll.c:718
 io_queue_async+0x25d/0x320 io_uring/io_uring.c:1615
 io_queue_sqe io_uring/io_uring.c:1641 [inline]
 io_req_task_submit+0x9b/0xa0 io_uring/io_uring.c:1044
 io_handle_tw_list+0x1f5/0x230 io_uring/tw.c:72
 tctx_task_work_run+0x42/0x170 io_uring/tw.c:132
 tctx_task_work+0x3f/0x80 io_uring/tw.c:150
 task_work_run+0x130/0x1a0 kernel/task_work.c:233
 get_signal+0xe0e/0xf60 kernel/signal.c:2807
 arch_do_signal_or_restart+0x96/0x450 arch/x86/kernel/signal.c:337
 __exit_to_user_mode_loop kernel/entry/common.c:64 [inline]
 exit_to_user_mode_loop+0x6a/0x6f0 kernel/entry/common.c:98
 __exit_to_user_mode_prepare include/linux/irq-entry-common.h:226 [inline]
 syscall_exit_to_user_mode_prepare include/linux/irq-entry-common.h:256 [inline]
 syscall_exit_to_user_mode include/linux/entry-common.h:325 [inline]
 do_syscall_64+0x249/0x370 arch/x86/entry/syscall_64.c:100
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff888237d1b898 of 2 bytes by task 19248 on cpu 0:
 print_cpu+0x35b/0x660 kernel/time/timer_list.c:134
 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: 0x5c29 -> 0x5c2a

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 19248 Comm: syz.9.3652 Tainted: G        W           syzkaller #0 PREEMPT(full) 
Tainted: [W]=WARN
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026
==================================================================