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BUG: KCSAN: data-race in __mark_inode_dirty / move_expired_inodes

write to 0xffff88821aa99550 of 8 bytes by task 29 on cpu 1:
 move_expired_inodes+0x1ca/0x4a0 fs/fs-writeback.c:1257
 queue_io+0xe1/0x2e0 fs/fs-writeback.c:1304
 wb_writeback+0x265/0x6f0 fs/fs-writeback.c:1892
 wb_do_writeback+0x101/0x5f0 fs/fs-writeback.c:2039
 wb_workfn+0xc8/0x470 fs/fs-writeback.c:2080
 process_one_work+0x3e1/0x9a0 kernel/workqueue.c:2269
 worker_thread+0x665/0xbe0 kernel/workqueue.c:2415
 kthread+0x20d/0x230 kernel/kthread.c:292
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:294

read to 0xffff88821aa99550 of 8 bytes by task 15198 on cpu 0:
 __mark_inode_dirty+0xb9/0x7f0 fs/fs-writeback.c:2274
 mark_buffer_dirty+0x14b/0x260 fs/buffer.c:1141
 __ext4_handle_dirty_metadata+0x20a/0x5a0 fs/ext4/ext4_jbd2.c:362
 ext4_do_update_inode fs/ext4/inode.c:5072 [inline]
 ext4_mark_iloc_dirty+0x1302/0x1660 fs/ext4/inode.c:5624
 __ext4_mark_inode_dirty+0x448/0x630 fs/ext4/inode.c:5818
 ext4_ext_tree_init+0x7e/0x90 fs/ext4/extents.c:828
 __ext4_new_inode+0x2990/0x2fc0 fs/ext4/ialloc.c:1184
 ext4_symlink+0x354/0x7e0 fs/ext4/namei.c:3315
 vfs_symlink+0x218/0x2d0 fs/namei.c:3959
 do_symlinkat+0xee/0x280 fs/namei.c:3986
 __do_sys_symlink fs/namei.c:4005 [inline]
 __se_sys_symlink fs/namei.c:4003 [inline]
 __x64_sys_symlink+0x32/0x40 fs/namei.c:4003
 do_syscall_64+0x39/0x80 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 15198 Comm: syz-executor.2 Not tainted 5.9.0-rc5-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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