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

write to 0xffff88812ab79e04 of 4 bytes by interrupt on cpu 1:
 calc_wb_limits.part.0+0x7b/0xb0 block/blk-wbt.c:304
 calc_wb_limits block/blk-wbt.c:298 [inline]
 scale_up block/blk-wbt.c:313 [inline]
 scale_up+0x7f/0x250 block/blk-wbt.c:309
 wb_timer_fn+0x2cd/0xad0 block/blk-wbt.c:393
 blk_stat_timer_fn+0x3b0/0x3d0 block/blk-stat.c:99
 call_timer_fn+0x5f/0x2f0 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+0xbe3/0xcb0 kernel/time/timer.c:1787
 __do_softirq+0x115/0x33f kernel/softirq.c:292
 invoke_softirq kernel/softirq.c:373 [inline]
 irq_exit+0xbb/0xe0 kernel/softirq.c:413
 exiting_irq arch/x86/include/asm/apic.h:546 [inline]
 smp_apic_timer_interrupt+0xe6/0x280 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+0x22c/0x3e0 kernel/kcsan/core.c:527
 check_access kernel/kcsan/core.c:564 [inline]
 __tsan_read8+0xc6/0x100 kernel/kcsan/core.c:700
 tomoyo_check_acl+0x19d/0x270 security/tomoyo/domain.c:171
 tomoyo_path_permission security/tomoyo/file.c:586 [inline]
 tomoyo_path_permission+0xe3/0x160 security/tomoyo/file.c:573
 tomoyo_check_open_permission+0x2b9/0x320 security/tomoyo/file.c:780
 tomoyo_file_open security/tomoyo/tomoyo.c:319 [inline]
 tomoyo_file_open+0x75/0x90 security/tomoyo/tomoyo.c:314
 security_file_open+0x69/0x210 security/security.c:1529
 do_dentry_open+0x211/0x970 fs/open.c:784
 vfs_open+0x62/0x80 fs/open.c:914
 do_last fs/namei.c:3490 [inline]
 path_openat+0xe32/0x3150 fs/namei.c:3607
 do_filp_open+0x11e/0x1b0 fs/namei.c:3637
 do_sys_openat2+0x4f5/0x620 fs/open.c:1149
 do_sys_open+0xa3/0x110 fs/open.c:1165
 ksys_open include/linux/syscalls.h:1386 [inline]
 __do_sys_open fs/open.c:1171 [inline]
 __se_sys_open fs/open.c:1169 [inline]
 __x64_sys_open+0x55/0x70 fs/open.c:1169
 do_syscall_64+0xcc/0x3a0 arch/x86/entry/common.c:294
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

read to 0xffff88812ab79e04 of 4 bytes by task 19554 on cpu 0:
 rwb_enabled block/blk-wbt.c:80 [inline]
 wb_timestamp block/blk-wbt.c:85 [inline]
 wbt_wait+0x1d0/0x260 block/blk-wbt.c:587
 __rq_qos_throttle+0x47/0x70 block/blk-rq-qos.c:72
 rq_qos_throttle block/blk-rq-qos.h:182 [inline]
 blk_mq_make_request+0x29c/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+0x96/0x3b0 block/blk-core.c:1195
 submit_bh_wbc+0x418/0x470 fs/buffer.c:3112
 submit_bh fs/buffer.c:3118 [inline]
 block_read_full_page+0x5c9/0x6d0 fs/buffer.c:2336
 blkdev_readpage+0x26/0x40 fs/block_dev.c:614
 generic_file_buffered_read mm/filemap.c:2166 [inline]
 generic_file_read_iter+0xbfa/0x1440 mm/filemap.c:2302
 blkdev_read_iter+0xb2/0xe0 fs/block_dev.c:2039
 call_read_iter include/linux/fs.h:1895 [inline]
 new_sync_read+0x389/0x4f0 fs/read_write.c:414
 __vfs_read+0xb1/0xc0 fs/read_write.c:427
 vfs_read fs/read_write.c:461 [inline]
 vfs_read+0x143/0x2c0 fs/read_write.c:446
 ksys_read+0xd5/0x1b0 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+0x4c/0x60 fs/read_write.c:595
 do_syscall_64+0xcc/0x3a0 arch/x86/entry/common.c:294
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 19554 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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