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BUG: KCSAN: data-race in calc_wb_limits.part.0 / wbt_wait

write to 0xffff88821b1fa204 of 4 bytes by interrupt on cpu 1:
 calc_wb_limits.part.0+0x70/0xa0 block/blk-wbt.c:304
 calc_wb_limits block/blk-wbt.c:298 [inline]
 scale_up block/blk-wbt.c:313 [inline]
 scale_up+0x7d/0x250 block/blk-wbt.c:309
 wb_timer_fn+0x2d6/0xad0 block/blk-wbt.c:382
 blk_stat_timer_fn+0x3af/0x3d0 block/blk-stat.c:99
 call_timer_fn+0x58/0x2e0 kernel/time/timer.c:1405
 expire_timers kernel/time/timer.c:1450 [inline]
 __run_timers kernel/time/timer.c:1774 [inline]
 __run_timers kernel/time/timer.c:1741 [inline]
 run_timer_softirq+0xb14/0xbd0 kernel/time/timer.c:1787
 __do_softirq+0x118/0x34a kernel/softirq.c:292
 invoke_softirq kernel/softirq.c:373 [inline]
 irq_exit+0xb5/0xd0 kernel/softirq.c:413
 exiting_irq arch/x86/include/asm/apic.h:546 [inline]
 smp_apic_timer_interrupt+0xe2/0x270 arch/x86/kernel/apic/apic.c:1146
 apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:829
 arch_local_irq_restore arch/x86/include/asm/paravirt.h:752 [inline]
 kcsan_setup_watchpoint+0x242/0x420 kernel/kcsan/core.c:521
 compound_head include/linux/page-flags.h:174 [inline]
 PageAnon include/linux/page-flags.h:463 [inline]
 mm_counter include/linux/mm.h:1665 [inline]
 copy_one_pte mm/memory.c:792 [inline]
 copy_pte_range mm/memory.c:841 [inline]
 copy_pmd_range mm/memory.c:892 [inline]
 copy_pud_range mm/memory.c:926 [inline]
 copy_p4d_range mm/memory.c:948 [inline]
 copy_page_range+0xb4e/0x1a40 mm/memory.c:1010
 dup_mmap kernel/fork.c:610 [inline]
 dup_mm+0x72e/0xb90 kernel/fork.c:1366
 copy_mm kernel/fork.c:1422 [inline]
 copy_process+0x39ad/0x3b10 kernel/fork.c:2087
 _do_fork+0xf7/0x790 kernel/fork.c:2436
 __do_sys_clone kernel/fork.c:2591 [inline]
 __se_sys_clone kernel/fork.c:2572 [inline]
 __x64_sys_clone+0x12e/0x170 kernel/fork.c:2572
 do_syscall_64+0xc7/0x390 arch/x86/entry/common.c:294
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

read to 0xffff88821b1fa204 of 4 bytes by task 6991 on cpu 0:
 rwb_enabled block/blk-wbt.c:80 [inline]
 bio_to_wbt_flags block/blk-wbt.c:551 [inline]
 wbt_wait+0x4d/0x260 block/blk-wbt.c:584
 __rq_qos_throttle+0x42/0x70 block/blk-rq-qos.c:72
 rq_qos_throttle block/blk-rq-qos.h:182 [inline]
 blk_mq_make_request+0x297/0xf60 block/blk-mq.c:1984
 generic_make_request block/blk-core.c:1069 [inline]
 generic_make_request+0x196/0x700 block/blk-core.c:1011
 submit_bio+0x8f/0x3a0 block/blk-core.c:1195
 mpage_bio_submit fs/mpage.c:66 [inline]
 mpage_readpages+0x325/0x370 fs/mpage.c:410
 blkdev_readpages+0x32/0x50 fs/block_dev.c:620
 read_pages+0xa2/0x2d0 mm/readahead.c:126
 __do_page_cache_readahead+0x358/0x380 mm/readahead.c:212
 force_page_cache_readahead+0x12c/0x1e0 mm/readahead.c:243
 page_cache_sync_readahead+0x1d1/0x1e0 mm/readahead.c:522
 generic_file_buffered_read mm/filemap.c:2029 [inline]
 generic_file_read_iter+0xeae/0x1490 mm/filemap.c:2302
 blkdev_read_iter+0xae/0xe0 fs/block_dev.c:2039
 call_read_iter include/linux/fs.h:1895 [inline]
 new_sync_read+0x306/0x450 fs/read_write.c:414
 __vfs_read+0x9e/0xb0 fs/read_write.c:427
 vfs_read fs/read_write.c:461 [inline]
 vfs_read+0x13e/0x2b0 fs/read_write.c:446
 ksys_read+0xc5/0x1a0 fs/read_write.c:587
 __do_sys_read fs/read_write.c:597 [inline]
 __se_sys_read fs/read_write.c:595 [inline]
 __x64_sys_read+0x49/0x60 fs/read_write.c:595
 do_syscall_64+0xc7/0x390 arch/x86/entry/common.c:294
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 6991 Comm: blkid Not tainted 5.6.0-rc1-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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