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BUG: KCSAN: data-race in rcu_gp_fqs_loop / rcu_preempt_deferred_qs_irqrestore

write to 0xffffffff85c7d190 of 8 bytes by task 5349 on cpu 0:
 rcu_preempt_deferred_qs_irqrestore+0x43d/0x580 kernel/rcu/tree_plugin.h:496
 rcu_read_unlock_special kernel/rcu/tree_plugin.h:644 [inline]
 __rcu_read_unlock+0x16a/0x3d0 kernel/rcu/tree_plugin.h:383
 rcu_read_unlock include/linux/rcupdate.h:670 [inline]
 __unlock_page_memcg+0x42/0xa0 mm/memcontrol.c:2019
 unlock_page_memcg+0x23/0x30 mm/memcontrol.c:2028
 mark_buffer_dirty+0x287/0x2c0 fs/buffer.c:1154
 __block_commit_write.isra.0+0x11f/0x170 fs/buffer.c:2081
 block_write_end+0x6d/0x140 fs/buffer.c:2159
 blkdev_write_end+0x5e/0x110 fs/block_dev.c:636
 generic_perform_write+0x1d3/0x320 mm/filemap.c:3320
 __generic_file_write_iter+0x251/0x380 mm/filemap.c:3438
 blkdev_write_iter fs/block_dev.c:2019 [inline]
 blkdev_write_iter+0x19c/0x2b0 fs/block_dev.c:1993
 call_write_iter include/linux/fs.h:1902 [inline]
 do_iter_readv_writev+0x487/0x5b0 fs/read_write.c:693
 do_iter_write fs/read_write.c:970 [inline]
 do_iter_write+0x13b/0x3c0 fs/read_write.c:951
 vfs_iter_write+0x5c/0x80 fs/read_write.c:983
 iter_file_splice_write+0x530/0x840 fs/splice.c:760
 do_splice_from fs/splice.c:863 [inline]
 direct_splice_actor+0xa0/0xc0 fs/splice.c:1037
 splice_direct_to_actor+0x22b/0x540 fs/splice.c:992
 do_splice_direct+0x161/0x1e0 fs/splice.c:1080
 do_sendfile+0x384/0x7f0 fs/read_write.c:1464
 __do_sys_sendfile64 fs/read_write.c:1525 [inline]
 __se_sys_sendfile64 fs/read_write.c:1511 [inline]
 __x64_sys_sendfile64+0x12a/0x140 fs/read_write.c:1511
 do_syscall_64+0xcc/0x3a0 arch/x86/entry/common.c:294
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

read to 0xffffffff85c7d190 of 8 bytes by task 10 on cpu 1:
 rcu_gp_fqs_loop+0x23c/0x580 kernel/rcu/tree.c:1667
 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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