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

write to 0xffff888128da2c04 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:1140
 apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:829
 arch_local_irq_restore arch/x86/include/asm/paravirt.h:759 [inline]
 kcsan_setup_watchpoint+0x25a/0x440 kernel/kcsan/core.c:542
 rcu_preempt_read_enter kernel/rcu/tree_plugin.h:355 [inline]
 __rcu_read_lock+0x2a/0x50 kernel/rcu/tree_plugin.h:375
 rcu_read_lock include/linux/rcupdate.h:599 [inline]
 lock_page_memcg+0x2e/0x110 mm/memcontrol.c:1996
 page_add_file_rmap+0x3d/0x460 mm/rmap.c:1200
 alloc_set_pte+0x45f/0xee0 mm/memory.c:3664
 finish_fault+0xd5/0x170 mm/memory.c:3709
 do_shared_fault mm/memory.c:3919 [inline]
 do_fault mm/memory.c:3979 [inline]
 handle_pte_fault mm/memory.c:4215 [inline]
 __handle_mm_fault+0x2585/0x2ec0 mm/memory.c:4345
 handle_mm_fault+0x21c/0x540 mm/memory.c:4382
 do_user_addr_fault arch/x86/mm/fault.c:1464 [inline]
 do_page_fault+0x48a/0xa96 arch/x86/mm/fault.c:1535
 page_fault+0x34/0x40 arch/x86/entry/entry_64.S:1203

read to 0xffff888128da2c04 of 4 bytes by task 7398 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:1998
 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
 submit_bh_wbc+0x40d/0x460 fs/buffer.c:3063
 __block_write_full_page+0x4f5/0x8e0 fs/buffer.c:1801
 block_write_full_page+0x1ba/0x1d0 fs/buffer.c:2987
 blkdev_writepage+0x2b/0x40 fs/block_dev.c:610
 __writepage+0x3d/0xb0 mm/page-writeback.c:2303
 write_cache_pages+0x400/0xa10 mm/page-writeback.c:2238
 generic_writepages mm/page-writeback.c:2329 [inline]
 generic_writepages+0x79/0xc0 mm/page-writeback.c:2318
 blkdev_writepages+0x23/0x40 fs/block_dev.c:2074
 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
 __sync_blockdev fs/block_dev.c:491 [inline]
 __sync_blockdev+0x84/0x90 fs/block_dev.c:486
 __sync_filesystem fs/sync.c:40 [inline]
 sync_filesystem+0x10b/0x1a0 fs/sync.c:64
 ovl_sync_fs+0x89/0xa0 fs/overlayfs/super.c:277
 __sync_filesystem fs/sync.c:39 [inline]
 sync_filesystem fs/sync.c:67 [inline]
 sync_filesystem+0x15d/0x1a0 fs/sync.c:48
 generic_shutdown_super+0x68/0x270 fs/super.c:448
 kill_anon_super+0x28/0x50 fs/super.c:1108
 deactivate_locked_super+0x5d/0xb0 fs/super.c:335
 deactivate_super fs/super.c:366 [inline]
 deactivate_super+0xca/0xe0 fs/super.c:362
 cleanup_mnt+0x27a/0x330 fs/namespace.c:1102
 __cleanup_mnt+0x1c/0x30 fs/namespace.c:1109
 task_work_run+0xba/0x120 kernel/task_work.c:123
 tracehook_notify_resume include/linux/tracehook.h:188 [inline]
 exit_to_usermode_loop+0x2ae/0x2c0 arch/x86/entry/common.c:165
 prepare_exit_to_usermode arch/x86/entry/common.c:196 [inline]
 syscall_return_slowpath arch/x86/entry/common.c:279 [inline]
 do_syscall_64+0x38b/0x3b0 arch/x86/entry/common.c:305
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 7398 Comm: syz-executor.5 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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