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BUG: KCSAN: data-race in __ext4_update_other_inode_time / writeback_single_inode

write to 0xffff888109b89240 of 8 bytes by task 4006 on cpu 0:
 inode_sync_complete fs/fs-writeback.c:1197 [inline]
 writeback_single_inode+0x4a4/0x530 fs/fs-writeback.c:1578
 sync_inode fs/fs-writeback.c:2602 [inline]
 sync_inode_metadata+0x52/0x70 fs/fs-writeback.c:2622
 ext4_fsync_nojournal fs/ext4/fsync.c:92 [inline]
 ext4_sync_file+0x335/0x6e0 fs/ext4/fsync.c:170
 vfs_fsync_range+0x107/0x120 fs/sync.c:200
 generic_write_sync include/linux/fs.h:2882 [inline]
 iomap_dio_complete+0x2de/0x380 fs/iomap/direct-io.c:125
 iomap_dio_rw+0x874/0x8c0 fs/iomap/direct-io.c:572
 ext4_dio_write_iter fs/ext4/file.c:545 [inline]
 ext4_file_write_iter+0xda4/0x1010 fs/ext4/file.c:653
 call_write_iter include/linux/fs.h:1908 [inline]
 new_sync_write fs/read_write.c:503 [inline]
 vfs_write+0x607/0x690 fs/read_write.c:578
 ksys_write+0xce/0x180 fs/read_write.c:631
 __do_sys_write fs/read_write.c:643 [inline]
 __se_sys_write fs/read_write.c:640 [inline]
 __x64_sys_write+0x3e/0x50 fs/read_write.c:640
 do_syscall_64+0x51/0xb0 arch/x86/entry/common.c:384
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

read to 0xffff888109b89240 of 8 bytes by task 4007 on cpu 1:
 __ext4_update_other_inode_time+0x45/0x570 fs/ext4/inode.c:4893
 ext4_update_other_inodes_time fs/ext4/inode.c:4940 [inline]
 ext4_do_update_inode fs/ext4/inode.c:5068 [inline]
 ext4_mark_iloc_dirty+0x1296/0x1660 fs/ext4/inode.c:5624
 __ext4_mark_inode_dirty+0x448/0x630 fs/ext4/inode.c:5818
 __ext4_ext_dirty fs/ext4/extents.c:169 [inline]
 ext4_ext_insert_extent+0x1382/0x2b80 fs/ext4/extents.c:2135
 ext4_ext_map_blocks+0x1776/0x20c0 fs/ext4/extents.c:4265
 ext4_map_blocks+0x6d3/0xf60 fs/ext4/inode.c:626
 ext4_iomap_alloc fs/ext4/inode.c:3402 [inline]
 ext4_iomap_begin+0x46e/0x5f0 fs/ext4/inode.c:3441
 iomap_apply+0x8a/0x520 fs/iomap/apply.c:46
 iomap_dio_rw+0x501/0x8c0 fs/iomap/direct-io.c:501
 ext4_dio_write_iter fs/ext4/file.c:545 [inline]
 ext4_file_write_iter+0xda4/0x1010 fs/ext4/file.c:653
 call_write_iter include/linux/fs.h:1908 [inline]
 new_sync_write fs/read_write.c:503 [inline]
 vfs_write+0x607/0x690 fs/read_write.c:578
 ksys_write+0xce/0x180 fs/read_write.c:631
 __do_sys_write fs/read_write.c:643 [inline]
 __se_sys_write fs/read_write.c:640 [inline]
 __x64_sys_write+0x3e/0x50 fs/read_write.c:640
 do_syscall_64+0x51/0xb0 arch/x86/entry/common.c:384
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 4007 Comm: syz-executor.4 Not tainted 5.8.0-rc4-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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