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BUG: KCSAN: data-race in find_next_bit / rcu_report_exp_cpu_mult

write to 0xffffffff85c7d140 of 8 bytes by task 8683 on cpu 1:
 rcu_report_exp_cpu_mult+0x4f/0xa0 kernel/rcu/tree_exp.h:244
 rcu_report_exp_rdp+0x6c/0x90 kernel/rcu/tree_exp.h:254
 rcu_preempt_deferred_qs_irqrestore+0x3bb/0x580 kernel/rcu/tree_plugin.h:464
 rcu_preempt_deferred_qs+0xae/0xf0 kernel/rcu/tree_plugin.h:574
 rcu_note_context_switch+0xa5/0x760 kernel/rcu/tree_plugin.h:317
 __schedule+0xa4/0x690 kernel/sched/core.c:4019
 preempt_schedule_common+0x37/0x90 kernel/sched/core.c:4236
 preempt_schedule+0x30/0x40 kernel/sched/core.c:4261
 ___preempt_schedule+0x16/0x18 arch/x86/entry/thunk_64.S:50
 __blk_mq_delay_run_hw_queue+0x343/0x3a0 block/blk-mq.c:1437
 blk_mq_run_hw_queue+0xfd/0x1c0 block/blk-mq.c:1473
 blk_mq_sched_insert_requests+0x198/0x260 block/blk-mq-sched.c:444
 blk_mq_flush_plug_list+0x572/0x6c0 block/blk-mq.c:1733
 blk_flush_plug_list+0x271/0x2a0 block/blk-core.c:1768
 blk_finish_plug block/blk-core.c:1785 [inline]
 blk_finish_plug+0x60/0x84 block/blk-core.c:1781
 fsync_buffers_list fs/buffer.c:760 [inline]
 sync_mapping_buffers+0x317/0x6e0 fs/buffer.c:563
 ext4_fsync_nojournal fs/ext4/fsync.c:88 [inline]
 ext4_sync_file+0x43b/0xaf0 fs/ext4/fsync.c:172
 vfs_fsync_range+0x82/0x150 fs/sync.c:197
 generic_write_sync include/linux/fs.h:2856 [inline]
 iomap_dio_complete+0x3bc/0x400 fs/iomap/direct-io.c:120
 iomap_dio_rw+0x8e3/0x9a0 fs/iomap/direct-io.c:569
 ext4_dio_write_iter fs/ext4/file.c:438 [inline]
 ext4_file_write_iter+0xc38/0xd40 fs/ext4/file.c:545
 call_write_iter include/linux/fs.h:1902 [inline]
 new_sync_write+0x388/0x4a0 fs/read_write.c:483
 __vfs_write+0xb1/0xc0 fs/read_write.c:496
 vfs_write fs/read_write.c:558 [inline]
 vfs_write+0x18a/0x390 fs/read_write.c:542
 ksys_write+0xd5/0x1b0 fs/read_write.c:611
 __do_sys_write fs/read_write.c:623 [inline]
 __se_sys_write fs/read_write.c:620 [inline]
 __x64_sys_write+0x4c/0x60 fs/read_write.c:620
 do_syscall_64+0xcc/0x3a0 arch/x86/entry/common.c:294
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

read to 0xffffffff85c7d140 of 8 bytes by task 7955 on cpu 0:
 _find_next_bit lib/find_bit.c:39 [inline]
 find_next_bit+0x57/0xe0 lib/find_bit.c:70
 sync_rcu_exp_select_node_cpus+0x28e/0x510 kernel/rcu/tree_exp.h:375
 sync_rcu_exp_select_cpus+0x30c/0x590 kernel/rcu/tree_exp.h:439
 rcu_exp_sel_wait_wake kernel/rcu/tree_exp.h:575 [inline]
 wait_rcu_exp_gp+0x25/0x40 kernel/rcu/tree_exp.h:589
 process_one_work+0x3d4/0x890 kernel/workqueue.c:2264
 worker_thread+0xa0/0x800 kernel/workqueue.c:2410
 kthread+0x1d4/0x200 drivers/block/aoe/aoecmd.c:1253
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:352

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 7955 Comm: kworker/0:4 Not tainted 5.5.0-rc1-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: rcu_gp wait_rcu_exp_gp
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