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BUG: KCSAN: data-race in rq_depth_scale_up / wbt_inflight_cb

write to 0xffff888129991fe0 of 4 bytes by interrupt on cpu 1:
 rq_depth_calc_max_depth block/blk-rq-qos.c:157 [inline]
 rq_depth_scale_up+0x169/0x190 block/blk-rq-qos.c:174
 scale_up block/blk-wbt.c:311 [inline]
 wb_timer_fn+0x15b/0xa30 block/blk-wbt.c:382
 blk_stat_timer_fn+0x3f4/0x410 block/blk-stat.c:99
 call_timer_fn+0x30/0x2a0 kernel/time/timer.c:1404
 expire_timers+0x116/0x290 kernel/time/timer.c:1449
 __run_timers+0x443/0x500 kernel/time/timer.c:1773
 run_timer_softirq+0x2e/0x60 kernel/time/timer.c:1786
 __do_softirq+0x198/0x360 kernel/softirq.c:292
 asm_call_on_stack+0xf/0x20 arch/x86/entry/entry_64.S:711
 __run_on_irqstack arch/x86/include/asm/irq_stack.h:22 [inline]
 run_on_irqstack_cond arch/x86/include/asm/irq_stack.h:48 [inline]
 do_softirq_own_stack+0x5d/0x80 arch/x86/kernel/irq_64.c:77
 invoke_softirq kernel/softirq.c:387 [inline]
 __irq_exit_rcu+0x115/0x120 kernel/softirq.c:417
 sysvec_apic_timer_interrupt+0xd9/0xf0 arch/x86/kernel/apic/apic.c:1091
 asm_sysvec_apic_timer_interrupt+0x12/0x20 arch/x86/include/asm/idtentry.h:596
 arch_local_irq_enable arch/x86/include/asm/paravirt.h:775 [inline]
 __raw_spin_unlock_irq include/linux/spinlock_api_smp.h:168 [inline]
 _raw_spin_unlock_irq+0x41/0x70 kernel/locking/spinlock.c:199
 finish_lock_switch kernel/sched/core.c:3169 [inline]
 finish_task_switch+0x8b/0x270 kernel/sched/core.c:3269
 context_switch kernel/sched/core.c:3433 [inline]
 __schedule+0x395/0x560 kernel/sched/core.c:4155
 preempt_schedule_common kernel/sched/core.c:4311 [inline]
 preempt_schedule+0x43/0xa0 kernel/sched/core.c:4336
 preempt_schedule_thunk+0x16/0x18 arch/x86/entry/thunk_64.S:40
 __raw_spin_unlock include/linux/spinlock_api_smp.h:152 [inline]
 _raw_spin_unlock+0x40/0x50 kernel/locking/spinlock.c:183
 spin_unlock include/linux/spinlock.h:393 [inline]
 minix_new_block+0x16a/0x200 fs/minix/bitmap.c:85
 alloc_branch fs/minix/itree_common.c:77 [inline]
 get_block+0x48d/0xd20 fs/minix/itree_common.c:191
 V1_minix_get_block+0x28/0x30 fs/minix/itree_v1.c:56
 minix_get_block+0x6d/0x90 fs/minix/inode.c:376
 __block_write_begin_int+0x36a/0xca0 fs/buffer.c:2012
 __block_write_begin fs/buffer.c:2062 [inline]
 block_write_begin+0x4f/0x190 fs/buffer.c:2121
 minix_write_begin+0x38/0x160 fs/minix/inode.c:412
 generic_perform_write+0x197/0x380 mm/filemap.c:3299
 __generic_file_write_iter+0x154/0x330 mm/filemap.c:3428
 generic_file_write_iter+0x2f3/0x3e0 mm/filemap.c:3460
 call_write_iter include/linux/fs.h:1907 [inline]
 new_sync_write fs/read_write.c:484 [inline]
 __vfs_write+0x2d8/0x340 fs/read_write.c:497
 vfs_write+0x19b/0x350 fs/read_write.c:559
 ksys_write+0xce/0x180 fs/read_write.c:612
 __do_sys_write fs/read_write.c:624 [inline]
 __se_sys_write fs/read_write.c:621 [inline]
 __x64_sys_write+0x3e/0x50 fs/read_write.c:621
 do_syscall_64+0x71/0x120 arch/x86/entry/common.c:359
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

read to 0xffff888129991fe0 of 4 bytes by task 12605 on cpu 0:
 get_limit block/blk-wbt.c:473 [inline]
 wbt_inflight_cb+0xc6/0x220 block/blk-wbt.c:495
 rq_qos_wait+0xac/0x220 block/blk-rq-qos.c:266
 __wbt_wait block/blk-wbt.c:518 [inline]
 wbt_wait+0x1bb/0x2b0 block/blk-wbt.c:583
 __rq_qos_throttle+0x39/0x70 block/blk-rq-qos.c:72
 rq_qos_throttle block/blk-rq-qos.h:182 [inline]
 blk_mq_make_request+0x237/0x1010 block/blk-mq.c:2050
 do_make_request block/blk-core.c:1084 [inline]
 generic_make_request+0x240/0x5c0 block/blk-core.c:1156
 submit_bio+0x200/0x370 block/blk-core.c:1275
 submit_bh_wbc+0x34e/0x390 fs/buffer.c:3073
 submit_bh fs/buffer.c:3079 [inline]
 __sync_dirty_buffer+0xfa/0x170 fs/buffer.c:3165
 sync_dirty_buffer+0x16/0x20 fs/buffer.c:3178
 ext4_write_inode+0x214/0x310 fs/ext4/inode.c:5165
 write_inode+0x8e/0x250 fs/fs-writeback.c:1312
 __writeback_single_inode+0x31c/0x610 fs/fs-writeback.c:1511
 writeback_single_inode+0x121/0x520 fs/fs-writeback.c:1565
 sync_inode fs/fs-writeback.c:2602 [inline]
 sync_inode_metadata+0x52/0x70 fs/fs-writeback.c:2622
 ext4_fsync_nojournal fs/ext4/fsync.c:92 [inline]
 ext4_sync_file+0x30c/0x680 fs/ext4/fsync.c:170
 vfs_fsync_range+0x107/0x120 fs/sync.c:200
 generic_write_sync include/linux/fs.h:2884 [inline]
 ext4_buffered_write_iter+0x34e/0x390 fs/ext4/file.c:277
 ext4_file_write_iter+0x4a3/0xfd0 fs/ext4/file.c:498
 call_write_iter include/linux/fs.h:1907 [inline]
 do_iter_readv_writev+0x321/0x3c0 fs/read_write.c:694
 do_iter_write+0x10e/0x470 fs/read_write.c:999
 vfs_iter_write+0x4c/0x70 fs/read_write.c:1040
 iter_file_splice_write+0x41a/0x770 fs/splice.c:750
 do_splice_from fs/splice.c:846 [inline]
 direct_splice_actor+0x95/0x160 fs/splice.c:1016
 splice_direct_to_actor+0x365/0x660 fs/splice.c:971
 do_splice_direct+0xf2/0x170 fs/splice.c:1059
 do_sendfile+0x562/0xb10 fs/read_write.c:1521
 __do_sys_sendfile64 fs/read_write.c:1576 [inline]
 __se_sys_sendfile64 fs/read_write.c:1568 [inline]
 __x64_sys_sendfile64+0xa9/0x130 fs/read_write.c:1568
 do_syscall_64+0x71/0x120 arch/x86/entry/common.c:359
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 12605 Comm: syz-executor.1 Not tainted 5.8.0-rc1-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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