syzbot

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BUG: KCSAN: data-race in hrtimer_interrupt / print_tickdevice

write to 0xffff888237c179e0 of 8 bytes by interrupt on cpu 0:
 hrtimer_interrupt+0x6b/0x810 kernel/time/hrtimer.c:2194
 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1051 [inline]
 __sysvec_apic_timer_interrupt+0x5f/0x1c0 arch/x86/kernel/apic/apic.c:1068
 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1062 [inline]
 sysvec_apic_timer_interrupt+0x32/0x80 arch/x86/kernel/apic/apic.c:1062
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:674
 get_ctx kernel/kcsan/core.c:206 [inline]
 check_access kernel/kcsan/core.c:750 [inline]
 __tsan_read8+0xc6/0x190 kernel/kcsan/core.c:1025
 pie_calculate_probability+0x45/0x4c0 net/sched/sch_pie.c:-1
 fq_pie_timer+0xf6/0x1d0 net/sched/sch_fq_pie.c:402
 call_timer_fn+0x3b/0x240 kernel/time/timer.c:1748
 expire_timers kernel/time/timer.c:1799 [inline]
 __run_timers kernel/time/timer.c:2374 [inline]
 __run_timer_base+0x40c/0x5f0 kernel/time/timer.c:2386
 run_timer_base kernel/time/timer.c:2395 [inline]
 run_timer_softirq+0x31/0x70 kernel/time/timer.c:2405
 handle_softirqs+0xb9/0x280 kernel/softirq.c:622
 __do_softirq kernel/softirq.c:656 [inline]
 invoke_softirq kernel/softirq.c:496 [inline]
 __irq_exit_rcu+0x42/0xd0 kernel/softirq.c:735
 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1062 [inline]
 sysvec_apic_timer_interrupt+0x74/0x80 arch/x86/kernel/apic/apic.c:1062
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:674
 is_atomic kernel/kcsan/core.c:264 [inline]
 should_watch kernel/kcsan/core.c:277 [inline]
 check_access kernel/kcsan/core.c:752 [inline]
 __tsan_unaligned_write8+0x134/0x180 kernel/kcsan/core.c:1025
 filemap_map_pages+0x2c1/0xef0 mm/filemap.c:3925
 do_fault_around mm/memory.c:5818 [inline]
 do_read_fault mm/memory.c:5851 [inline]
 do_fault mm/memory.c:5994 [inline]
 do_pte_missing mm/memory.c:4566 [inline]
 handle_pte_fault mm/memory.c:6379 [inline]
 __handle_mm_fault mm/memory.c:6517 [inline]
 handle_mm_fault+0x14c5/0x2da0 mm/memory.c:6686
 faultin_page mm/gup.c:1126 [inline]
 __get_user_pages+0x129c/0x1f10 mm/gup.c:1428
 populate_vma_page_range mm/gup.c:1860 [inline]
 __mm_populate+0x242/0x390 mm/gup.c:1963
 mm_populate include/linux/mm.h:4171 [inline]
 vm_mmap_pgoff+0x23b/0x2d0 mm/util.c:586
 ksys_mmap_pgoff+0xc1/0x310 mm/mmap.c:606
 x64_sys_call+0x14df/0x3020 arch/x86/include/generated/asm/syscalls_64.h:10
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x136/0x3c0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff888237c179e0 of 8 bytes by task 7545 on cpu 1:
 print_tickdevice+0x144/0x340 kernel/time/timer_list.c:200
 timer_list_show+0x6c/0x170 kernel/time/timer_list.c:292
 seq_read_iter+0x5f6/0x8f0 fs/seq_file.c:273
 proc_reg_read_iter+0x110/0x180 fs/proc/inode.c:299
 copy_splice_read+0x47a/0x6b0 fs/splice.c:362
 do_splice_read fs/splice.c:980 [inline]
 splice_direct_to_actor+0x261/0x680 fs/splice.c:1084
 do_splice_direct_actor fs/splice.c:1202 [inline]
 do_splice_direct+0x119/0x1a0 fs/splice.c:1228
 do_sendfile+0x37d/0x640 fs/read_write.c:1371
 __do_sys_sendfile64 fs/read_write.c:1432 [inline]
 __se_sys_sendfile64 fs/read_write.c:1418 [inline]
 __x64_sys_sendfile64+0x105/0x150 fs/read_write.c:1418
 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+0x136/0x3c0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x00000045d3291b56 -> 0x00000045d32d3a06

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 7545 Comm: syz.2.954 Not tainted syzkaller #0 PREEMPT(lazy) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/09/2026
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