syzbot

BUG: KCSAN: data-race in hrtimer_interrupt / print_tickdevice

write to 0xffff888237c17318 of 8 bytes by interrupt on cpu 0:
 hrtimer_interrupt+0x80/0x4a0 kernel/time/hrtimer.c:1896
 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1038 [inline]
 __sysvec_apic_timer_interrupt+0x5c/0x1d0 arch/x86/kernel/apic/apic.c:1055
 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1049 [inline]
 sysvec_apic_timer_interrupt+0x6e/0x80 arch/x86/kernel/apic/apic.c:1049
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:702
 kcsan_setup_watchpoint+0x404/0x410 kernel/kcsan/core.c:705
 EXT4_SB fs/ext4/ext4.h:1769 [inline]
 ext4_page_mkwrite+0x23e/0xba0 fs/ext4/inode.c:6222
 do_page_mkwrite mm/memory.c:3253 [inline]
 do_shared_fault mm/memory.c:5487 [inline]
 do_fault mm/memory.c:5549 [inline]
 do_pte_missing mm/memory.c:4056 [inline]
 handle_pte_fault mm/memory.c:5890 [inline]
 __handle_mm_fault mm/memory.c:6033 [inline]
 handle_mm_fault+0x130c/0x2b30 mm/memory.c:6202
 do_user_addr_fault arch/x86/mm/fault.c:1337 [inline]
 handle_page_fault arch/x86/mm/fault.c:1480 [inline]
 exc_page_fault+0x3b9/0x650 arch/x86/mm/fault.c:1538
 asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:623

read to 0xffff888237c17318 of 8 bytes by task 6002 on cpu 1:
 print_tickdevice+0x144/0x340 kernel/time/timer_list.c:208
 timer_list_show+0x79/0x180 kernel/time/timer_list.c:300
 traverse+0x155/0x3c0 fs/seq_file.c:111
 seq_read_iter+0x89f/0x970 fs/seq_file.c:195
 proc_reg_read_iter+0x118/0x190 fs/proc/inode.c:299
 new_sync_read fs/read_write.c:489 [inline]
 vfs_read+0x5e6/0x710 fs/read_write.c:570
 ksys_pread64 fs/read_write.c:761 [inline]
 __do_sys_pread64 fs/read_write.c:769 [inline]
 __se_sys_pread64 fs/read_write.c:766 [inline]
 __x64_sys_pread64+0xfb/0x150 fs/read_write.c:766
 x64_sys_call+0x26ad/0x2e10 arch/x86/include/generated/asm/syscalls_64.h:18
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xc9/0x1c0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x0000000ccb368f9c -> 0x0000000ccb4014f4

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 6002 Comm: syz.2.1193 Not tainted 6.14.0-syzkaller-11270-g08733088b566 #0 PREEMPT(voluntary) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025
==================================================================