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

write to 0xffff88821aa71d04 of 4 bytes by interrupt on cpu 0:
 calc_wb_limits.part.0+0x7b/0xb0 block/blk-wbt.c:304
 calc_wb_limits block/blk-wbt.c:326 [inline]
 scale_down.part.0+0xcb/0x230 block/blk-wbt.c:323
 scale_down block/blk-wbt.c:321 [inline]
 wb_timer_fn+0x6f9/0xad0 block/blk-wbt.c:395
 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
 get_current arch/x86/include/asm/current.h:15 [inline]
 __sanitizer_cov_trace_pc+0xd/0x50 kernel/kcov.c:186
 tomoyo_domain_quota_is_ok+0x247/0x2b0 security/tomoyo/util.c:1070
 tomoyo_supervisor+0x1d9/0xc90 security/tomoyo/common.c:2089
 tomoyo_audit_path_log security/tomoyo/file.c:168 [inline]
 tomoyo_path_permission security/tomoyo/file.c:587 [inline]
 tomoyo_path_permission+0x121/0x160 security/tomoyo/file.c:573
 tomoyo_path_perm+0x2c6/0x390 security/tomoyo/file.c:838
 tomoyo_path_symlink+0x69/0xa0 security/tomoyo/tomoyo.c:206
 security_path_symlink+0xab/0xe0 security/security.c:1085
 do_symlinkat+0xcd/0x1e0 fs/namei.c:4226
 __do_sys_symlink fs/namei.c:4247 [inline]
 __se_sys_symlink fs/namei.c:4245 [inline]
 __x64_sys_symlink+0x3f/0x50 fs/namei.c:4245
 do_syscall_64+0xcc/0x3a0 arch/x86/entry/common.c:294
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

read to 0xffff88821aa71d04 of 4 bytes by task 13915 on cpu 1:
 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
 mpage_bio_submit fs/mpage.c:66 [inline]
 mpage_readpages+0x36a/0x3c0 fs/mpage.c:410
 blkdev_readpages+0x36/0x50 fs/block_dev.c:620
 read_pages+0xa2/0x2d0 mm/readahead.c:126
 __do_page_cache_readahead+0x353/0x390 mm/readahead.c:212
 force_page_cache_readahead+0x13a/0x1f0 mm/readahead.c:243
 page_cache_sync_readahead+0x1cf/0x1e0 mm/readahead.c:522
 generic_file_buffered_read mm/filemap.c:2029 [inline]
 generic_file_read_iter+0xeb6/0x1440 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: 1 PID: 13915 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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