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BUG: KCSAN: data-race in __mark_inode_dirty / __writeback_single_inode

write to 0xffff88821b83e570 of 8 bytes by task 7363 on cpu 0:
 __writeback_single_inode+0x328/0x8e0 fs/fs-writeback.c:1483
 writeback_sb_inodes+0x4ba/0xa50 fs/fs-writeback.c:1713
 __writeback_inodes_wb+0xe8/0x1b0 fs/fs-writeback.c:1782
 wb_writeback+0x557/0x6a0 fs/fs-writeback.c:1891
 wb_check_start_all fs/fs-writeback.c:2015 [inline]
 wb_do_writeback fs/fs-writeback.c:2041 [inline]
 wb_workfn+0x748/0x970 fs/fs-writeback.c:2075
 process_one_work+0x3d4/0x890 kernel/workqueue.c:2269
 worker_thread+0xa0/0x800 kernel/workqueue.c:2415
 kthread+0x1d4/0x200 drivers/block/aoe/aoecmd.c:1253
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:352

read to 0xffff88821b83e570 of 8 bytes by task 10662 on cpu 1:
 __mark_inode_dirty+0xb8/0x940 fs/fs-writeback.c:2269
 mark_buffer_dirty+0x29c/0x2c0 fs/buffer.c:1116
 __ext4_handle_dirty_metadata+0x284/0x350 fs/ext4/ext4_jbd2.c:298
 __ext4_new_inode+0x101f/0x3070 fs/ext4/ialloc.c:973
 ext4_symlink+0x30e/0x970 fs/ext4/namei.c:3262
 vfs_symlink fs/namei.c:4119 [inline]
 vfs_symlink+0x218/0x310 fs/namei.c:4105
 do_symlinkat+0x1a5/0x1e0 fs/namei.c:4146
 __do_sys_symlink fs/namei.c:4165 [inline]
 __se_sys_symlink fs/namei.c:4163 [inline]
 __x64_sys_symlink+0x3f/0x50 fs/namei.c:4163
 do_syscall_64+0xcc/0x370 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 10662 Comm: syz-executor.4 Not tainted 5.4.0-rc3+ #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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