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

write to 0xffff8881290b3504 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
 run_ksoftirqd+0x41/0x60 kernel/softirq.c:603
 smpboot_thread_fn+0x374/0x4a0 kernel/smpboot.c:165
 kthread+0x1cb/0x1f0 kernel/kthread.c:255
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:352

read to 0xffff8881290b3504 of 4 bytes by task 17154 on cpu 0:
 rwb_enabled block/blk-wbt.c:80 [inline]
 bio_to_wbt_flags block/blk-wbt.c:551 [inline]
 wbt_track+0x34/0x90 block/blk-wbt.c:600
 __rq_qos_track+0x4b/0x80 block/blk-rq-qos.c:81
 rq_qos_track block/blk-rq-qos.h:189 [inline]
 blk_mq_make_request+0x32c/0xf60 block/blk-mq.c:1997
 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
 submit_bh_wbc+0x40d/0x460 fs/buffer.c:3112
 submit_bh fs/buffer.c:3118 [inline]
 write_dirty_buffer fs/buffer.c:3186 [inline]
 write_dirty_buffer+0x7d/0xf0 fs/buffer.c:3177
 fsync_buffers_list fs/buffer.c:745 [inline]
 sync_mapping_buffers+0x2b8/0x720 fs/buffer.c:563
 ext4_sync_parent fs/ext4/fsync.c:72 [inline]
 ext4_fsync_nojournal fs/ext4/fsync.c:99 [inline]
 ext4_sync_file+0x564/0x8b0 fs/ext4/fsync.c:172
 vfs_fsync_range+0x7c/0x150 fs/sync.c:197
 vfs_fsync fs/sync.c:211 [inline]
 do_fsync+0x57/0x90 fs/sync.c:221
 __do_sys_fdatasync fs/sync.c:234 [inline]
 __se_sys_fdatasync fs/sync.c:232 [inline]
 __x64_sys_fdatasync+0x2a/0x40 fs/sync.c:232
 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: 17154 Comm: syz-executor.2 Not tainted 5.6.0-rc1-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
==================================================================