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BUG: KCSAN: data-race in __writeback_single_inode / generic_buffers_fsync_noflush

read-write to 0xffff88812d12b3f0 of 8 bytes by task 6711 on cpu 1:
 __writeback_single_inode+0x201/0x860 fs/fs-writeback.c:1661
 writeback_single_inode+0x12f/0x4a0 fs/fs-writeback.c:1746
 sync_inode_metadata+0x56/0x80 fs/fs-writeback.c:2808
 generic_buffers_fsync_noflush+0xe4/0x120 fs/buffer.c:613
 ext4_fsync_nojournal fs/ext4/fsync.c:88 [inline]
 ext4_sync_file+0x206/0x6c0 fs/ext4/fsync.c:151
 vfs_fsync_range+0x111/0x120 fs/sync.c:188
 generic_write_sync include/linux/fs.h:2734 [inline]
 ext4_buffered_write_iter+0x334/0x370 fs/ext4/file.c:305
 ext4_file_write_iter+0x297/0xe10
 call_write_iter include/linux/fs.h:2084 [inline]
 iter_file_splice_write+0x4e0/0x840 fs/splice.c:743
 do_splice_from fs/splice.c:941 [inline]
 direct_splice_actor+0x167/0x2c0 fs/splice.c:1164
 splice_direct_to_actor+0x2fb/0x650 fs/splice.c:1108
 do_splice_direct_actor fs/splice.c:1207 [inline]
 do_splice_direct+0xd7/0x150 fs/splice.c:1233
 do_sendfile+0x377/0x880 fs/read_write.c:1295
 __do_sys_sendfile64 fs/read_write.c:1362 [inline]
 __se_sys_sendfile64 fs/read_write.c:1348 [inline]
 __x64_sys_sendfile64+0x110/0x150 fs/read_write.c:1348
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0x44/0x110 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x63/0x6b

read to 0xffff88812d12b3f0 of 8 bytes by task 6714 on cpu 0:
 generic_buffers_fsync_noflush+0x89/0x120 fs/buffer.c:608
 ext4_fsync_nojournal fs/ext4/fsync.c:88 [inline]
 ext4_sync_file+0x206/0x6c0 fs/ext4/fsync.c:151
 vfs_fsync_range+0x111/0x120 fs/sync.c:188
 generic_write_sync include/linux/fs.h:2734 [inline]
 ext4_buffered_write_iter+0x334/0x370 fs/ext4/file.c:305
 ext4_file_write_iter+0x297/0xe10
 call_write_iter include/linux/fs.h:2084 [inline]
 iter_file_splice_write+0x4e0/0x840 fs/splice.c:743
 do_splice_from fs/splice.c:941 [inline]
 direct_splice_actor+0x167/0x2c0 fs/splice.c:1164
 splice_direct_to_actor+0x2fb/0x650 fs/splice.c:1108
 do_splice_direct_actor fs/splice.c:1207 [inline]
 do_splice_direct+0xd7/0x150 fs/splice.c:1233
 do_sendfile+0x377/0x880 fs/read_write.c:1295
 __do_sys_sendfile64 fs/read_write.c:1362 [inline]
 __se_sys_sendfile64 fs/read_write.c:1348 [inline]
 __x64_sys_sendfile64+0x110/0x150 fs/read_write.c:1348
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0x44/0x110 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x63/0x6b

value changed: 0x0000000000000084 -> 0x0000000000000000

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 6714 Comm: syz-executor.3 Tainted: G        W          6.7.0-syzkaller-00119-g5db8752c3b81 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 11/17/2023
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