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BUG: KCSAN: data-race in rcu_gp_fqs_check_wake / rcu_note_context_switch

write to 0xffffffff85c7d0d0 of 8 bytes by task 12925 on cpu 0:
 rcu_preempt_ctxt_queue kernel/rcu/tree_plugin.h:223 [inline]
 rcu_note_context_switch+0x6f6/0x760 kernel/rcu/tree_plugin.h:315
 __schedule+0xa4/0x690 kernel/sched/core.c:4019
 preempt_schedule_irq+0x57/0x90 kernel/sched/core.c:4338
 restore_regs_and_return_to_kernel+0x0/0x25
 memcg_kmem_get_cache+0x8e/0x320 mm/memcontrol.c:2762
 slab_pre_alloc_hook mm/slab.h:572 [inline]
 slab_alloc mm/slab.c:3306 [inline]
 kmem_cache_alloc+0x117/0x5d0 mm/slab.c:3484
 __d_alloc+0x52/0x4b0 fs/dcache.c:1690
 d_alloc_pseudo+0x27/0x70 fs/dcache.c:1819
 alloc_file_pseudo+0x96/0x1b0 fs/file_table.c:225
 dma_buf_getfile drivers/dma-buf/dma-buf.c:441 [inline]
 dma_buf_export+0x391/0x590 drivers/dma-buf/dma-buf.c:554
 ion_alloc drivers/staging/android/ion/ion.c:400 [inline]
 ion_ioctl+0x4dd/0xab0 drivers/staging/android/ion/ion.c:509
 vfs_ioctl fs/ioctl.c:47 [inline]
 file_ioctl fs/ioctl.c:545 [inline]
 do_vfs_ioctl+0x84f/0xcf0 fs/ioctl.c:732
 ksys_ioctl+0xbd/0xe0 fs/ioctl.c:749
 __do_sys_ioctl fs/ioctl.c:756 [inline]
 __se_sys_ioctl fs/ioctl.c:754 [inline]
 __x64_sys_ioctl+0x4c/0x60 fs/ioctl.c:754
 do_syscall_64+0xcc/0x3a0 arch/x86/entry/common.c:294
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

read to 0xffffffff85c7d0d0 of 8 bytes by task 10 on cpu 1:
 rcu_gp_fqs_check_wake kernel/rcu/tree.c:1606 [inline]
 rcu_gp_fqs_check_wake+0x93/0xd0 kernel/rcu/tree.c:1596
 rcu_gp_fqs_loop+0x1df/0x580 kernel/rcu/tree.c:1661
 rcu_gp_kthread+0x143/0x230 kernel/rcu/tree.c:1821
 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: 10 Comm: rcu_preempt Not tainted 5.5.0-rc1-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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