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BUG: KCSAN: data-race in find_next_bit / rcu_report_exp_cpu_mult

write to 0xffffffff85c7d080 of 8 bytes by interrupt on cpu 0:
 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_exp_handler+0xe5/0x190 kernel/rcu/tree_exp.h:616
 flush_smp_call_function_queue+0x18c/0x2b0 kernel/smp.c:248
 generic_smp_call_function_single_interrupt+0x1c/0x49 kernel/smp.c:193
 smp_call_function_single_interrupt+0x3f/0x100 arch/x86/kernel/smp.c:262
 call_function_single_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:851
 get_task_policy.part.0+0x59/0x90 mm/mempolicy.c:142
 get_task_policy mm/mempolicy.c:2205 [inline]
 alloc_pages_current+0x168/0x170 mm/mempolicy.c:2198
 alloc_pages include/linux/gfp.h:532 [inline]
 __vmalloc_area_node mm/vmalloc.c:2483 [inline]
 __vmalloc_node_range+0x2d7/0x4c0 mm/vmalloc.c:2547
 vmalloc_user+0x65/0x80 mm/vmalloc.c:2682
 kcov_mmap+0x2e/0x150 kernel/kcov.c:450
 call_mmap include/linux/fs.h:1907 [inline]
 mmap_region+0x7df/0xd50 mm/mmap.c:1784
 do_mmap+0x6c8/0xba0 mm/mmap.c:1555
 do_mmap_pgoff include/linux/mm.h:2338 [inline]
 vm_mmap_pgoff+0x12d/0x190 mm/util.c:506
 ksys_mmap_pgoff+0x2d8/0x420 mm/mmap.c:1607
 __do_sys_mmap arch/x86/kernel/sys_x86_64.c:100 [inline]
 __se_sys_mmap arch/x86/kernel/sys_x86_64.c:91 [inline]
 __x64_sys_mmap+0x2e/0x40 arch/x86/kernel/sys_x86_64.c:91
 do_syscall_64+0xcc/0x3a0 arch/x86/entry/common.c:294
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

read to 0xffffffff85c7d080 of 8 bytes by task 2612 on cpu 1:
 _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: 1 PID: 2612 Comm: kworker/1:2 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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