syzbot

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BUG: KCSAN: data-race in hrtimer_interrupt / print_tickdevice

write to 0xffff888237c17758 of 8 bytes by interrupt on cpu 0:
 hrtimer_interrupt+0x7d/0x460 kernel/time/hrtimer.c:1866
 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
 kcsan_setup_watchpoint+0x415/0x430 kernel/kcsan/core.c:705
 fat_get_entry+0x3c/0x5d0 fs/fat/dir.c:121
 fat_get_short_entry fs/fat/dir.c:885 [inline]
 fat_subdirs+0xf6/0x190 fs/fat/dir.c:951
 fat_read_root+0x316/0x360 fs/fat/inode.c:1345
 fat_fill_super+0x15bf/0x1ce0 fs/fat/inode.c:1814
 vfat_fill_super+0x24/0x30 fs/fat/namei_vfat.c:1197
 get_tree_bdev_flags+0x291/0x300 fs/super.c:1679
 get_tree_bdev+0x1f/0x30 fs/super.c:1702
 vfat_get_tree+0x1c/0x30 fs/fat/namei_vfat.c:1202
 vfs_get_tree+0x54/0x1d0 fs/super.c:1802
 do_new_mount+0x207/0x680 fs/namespace.c:3856
 path_mount+0x4a4/0xb20 fs/namespace.c:4180
 do_mount fs/namespace.c:4193 [inline]
 __do_sys_mount fs/namespace.c:4404 [inline]
 __se_sys_mount+0x28f/0x2e0 fs/namespace.c:4381
 __x64_sys_mount+0x67/0x80 fs/namespace.c:4381
 x64_sys_call+0xd36/0x2fb0 arch/x86/include/generated/asm/syscalls_64.h:166
 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

read to 0xffff888237c17758 of 8 bytes by task 19746 on cpu 1:
 print_tickdevice+0x142/0x340 kernel/time/timer_list.c:208
 timer_list_show+0x6c/0x170 kernel/time/timer_list.c:300
 seq_read_iter+0x62a/0x940 fs/seq_file.c:272
 proc_reg_read_iter+0x110/0x180 fs/proc/inode.c:299
 copy_splice_read+0x3c1/0x5f0 fs/splice.c:363
 do_splice_read fs/splice.c:979 [inline]
 splice_direct_to_actor+0x26c/0x680 fs/splice.c:1083
 do_splice_direct_actor fs/splice.c:1201 [inline]
 do_splice_direct+0xda/0x150 fs/splice.c:1227
 do_sendfile+0x380/0x650 fs/read_write.c:1370
 __do_sys_sendfile64 fs/read_write.c:1431 [inline]
 __se_sys_sendfile64 fs/read_write.c:1417 [inline]
 __x64_sys_sendfile64+0x105/0x150 fs/read_write.c:1417
 x64_sys_call+0xb39/0x2fb0 arch/x86/include/generated/asm/syscalls_64.h:41
 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: 0x000000535d1582ab -> 0x000000535d1d89ab

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 19746 Comm: syz.4.5658 Not tainted 6.15.0-syzkaller-12426-ge271ed52b344 #0 PREEMPT(voluntary) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
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