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BUG: KCSAN: data-race in __ext4_update_other_inode_time / writeback_single_inode

write to 0xffff888009400398 of 8 bytes by task 25782 on cpu 1:
 inode_io_list_del_locked fs/fs-writeback.c:148 [inline]
 writeback_single_inode+0x2e9/0x580 fs/fs-writeback.c:1581
 sync_inode fs/fs-writeback.c:2606 [inline]
 sync_inode_metadata+0x52/0x70 fs/fs-writeback.c:2626
 ext4_fsync_nojournal fs/ext4/fsync.c:92 [inline]
 ext4_sync_file+0x359/0x6c0 fs/ext4/fsync.c:170
 vfs_fsync_range+0x107/0x120 fs/sync.c:200
 generic_write_sync include/linux/fs.h:2739 [inline]
 ext4_buffered_write_iter+0x384/0x3d0 fs/ext4/file.c:278
 ext4_file_write_iter+0x45e/0x1090 fs/ext4/file.c:503
 call_write_iter include/linux/fs.h:1903 [inline]
 do_iter_readv_writev+0x2cb/0x360 fs/read_write.c:740
 do_iter_write+0x112/0x4b0 fs/read_write.c:866
 vfs_iter_write+0x4c/0x70 fs/read_write.c:907
 iter_file_splice_write+0x42a/0x780 fs/splice.c:686
 do_splice_from fs/splice.c:764 [inline]
 direct_splice_actor+0x80/0xa0 fs/splice.c:933
 splice_direct_to_actor+0x345/0x650 fs/splice.c:888
 do_splice_direct+0xf5/0x170 fs/splice.c:976
 do_sendfile+0x5db/0xca0 fs/read_write.c:1257
 __do_sys_sendfile64 fs/read_write.c:1312 [inline]
 __se_sys_sendfile64 fs/read_write.c:1304 [inline]
 __x64_sys_sendfile64+0xa9/0x130 fs/read_write.c:1304
 do_syscall_64+0x39/0x80 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

read to 0xffff888009400398 of 8 bytes by task 25796 on cpu 0:
 __ext4_update_other_inode_time+0x45/0x550 fs/ext4/inode.c:4955
 ext4_update_other_inodes_time fs/ext4/inode.c:5002 [inline]
 ext4_do_update_inode fs/ext4/inode.c:5131 [inline]
 ext4_mark_iloc_dirty+0x1286/0x1650 fs/ext4/inode.c:5712
 __ext4_mark_inode_dirty+0x450/0x610 fs/ext4/inode.c:5906
 ext4_ext_tree_init+0x7e/0x90 fs/ext4/extents.c:828
 __ext4_new_inode+0x2a8e/0x3060 fs/ext4/ialloc.c:1326
 ext4_symlink+0x2bc/0x770 fs/ext4/namei.c:3336
 vfs_symlink+0x216/0x2d0 fs/namei.c:3960
 do_symlinkat+0xee/0x280 fs/namei.c:3987
 __do_sys_symlink fs/namei.c:4006 [inline]
 __se_sys_symlink fs/namei.c:4004 [inline]
 __x64_sys_symlink+0x32/0x40 fs/namei.c:4004
 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: 25796 Comm: syz-executor.1 Not tainted 5.10.0-rc7-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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