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BUG: KCSAN: data-race in ext4_truncate / writeback_single_inode

write to 0xffff8881302e0b18 of 8 bytes by task 26023 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:2602 [inline]
 sync_inode_metadata+0x52/0x70 fs/fs-writeback.c:2622
 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:2737 [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:1901 [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 0xffff8881302e0b18 of 8 bytes by task 26048 on cpu 0:
 ext4_truncate+0x40/0xbb0 fs/ext4/inode.c:4198
 ext4_setattr+0xb9e/0xf60 fs/ext4/inode.c:5493
 notify_change+0x7b3/0xa50 fs/attr.c:336
 do_truncate+0xe0/0x120 fs/open.c:64
 handle_truncate fs/namei.c:2910 [inline]
 do_open fs/namei.c:3256 [inline]
 path_openat+0x1a37/0x20a0 fs/namei.c:3369
 do_filp_open+0xbd/0x1d0 fs/namei.c:3396
 do_sys_openat2+0xa3/0x240 fs/open.c:1172
 do_sys_open fs/open.c:1188 [inline]
 __do_sys_open fs/open.c:1196 [inline]
 __se_sys_open fs/open.c:1192 [inline]
 __x64_sys_open+0xe2/0x110 fs/open.c:1192
 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: 26048 Comm: syz-executor.3 Not tainted 5.10.0-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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