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BUG: KCSAN: data-race in tick_nohz_idle_stop_tick / tick_sched_do_timer

write to 0xffffffff85f0ef50 of 4 bytes by interrupt on cpu 1:
 tick_sched_do_timer+0xb4/0xd0 kernel/time/tick-sched.c:141
 tick_sched_timer+0x3f/0xd0 kernel/time/tick-sched.c:1313
 __run_hrtimer kernel/time/hrtimer.c:1520 [inline]
 __hrtimer_run_queues+0x271/0x600 kernel/time/hrtimer.c:1584
 hrtimer_interrupt+0x226/0x490 kernel/time/hrtimer.c:1646
 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1113 [inline]
 smp_apic_timer_interrupt+0xd8/0x270 arch/x86/kernel/apic/apic.c:1138
 apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:829
 __sanitizer_cov_trace_pc+0x1a/0x50 kernel/kcov.c:183
 bio_disassociate_blkg block/bio.c:1611 [inline]
 __bio_associate_blkg.isra.0+0x33/0x220 block/bio.c:1634
 bio_clone_blkg_association+0x41/0x60 block/bio.c:1729
 __bio_clone_fast+0x181/0x220 block/bio.c:688
 bio_clone_fast+0x43/0xc0 block/bio.c:709
 bio_split+0x6f/0x170 block/bio.c:1448
 blk_bio_segment_split block/blk-merge.c:281 [inline]
 __blk_queue_split+0x613/0xc40 block/blk-merge.c:331
 blk_mq_make_request+0x109/0xf60 block/blk-mq.c:1986
 generic_make_request block/blk-core.c:1075 [inline]
 generic_make_request+0x196/0x700 block/blk-core.c:1017
 submit_bio+0x8f/0x3a0 block/blk-core.c:1200
 ext4_io_submit+0xdf/0x110 fs/ext4/page-io.c:382
 ext4_writepages+0xd96/0x1e10 fs/ext4/inode.c:2800
 do_writepages+0x6b/0x170 mm/page-writeback.c:2344
 __filemap_fdatawrite_range+0x1bb/0x220 mm/filemap.c:421
 __filemap_fdatawrite mm/filemap.c:429 [inline]
 filemap_flush+0x2a/0x40 mm/filemap.c:456
 collapse_file+0x26cf/0x26f0 mm/khugepaged.c:1639
 khugepaged_scan_file mm/khugepaged.c:1920 [inline]
 khugepaged_scan_mm_slot mm/khugepaged.c:2016 [inline]
 khugepaged_do_scan mm/khugepaged.c:2100 [inline]
 khugepaged+0x1d86/0x2740 mm/khugepaged.c:2145
 kthread+0x203/0x230 kernel/kthread.c:268
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:352

read to 0xffffffff85f0ef50 of 4 bytes by task 0 on cpu 0:
 tick_nohz_stop_tick kernel/time/tick-sched.c:780 [inline]
 __tick_nohz_idle_stop_tick kernel/time/tick-sched.c:973 [inline]
 tick_nohz_idle_stop_tick+0x191/0x680 kernel/time/tick-sched.c:994
 cpuidle_idle_call kernel/sched/idle.c:151 [inline]
 do_idle+0x1ad/0x290 kernel/sched/idle.c:269
 cpu_startup_entry+0x14/0x20 kernel/sched/idle.c:361
 rest_init+0xe4/0xeb init/main.c:667
 arch_call_rest_init+0x13/0x2b
 start_kernel+0x82d/0x852 init/main.c:1005
 secondary_startup_64+0xa4/0xb0 arch/x86/kernel/head_64.S:242

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 0 Comm: swapper/0 Not tainted 5.7.0-rc1-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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