==================================================================
BUG: KCSAN: data-race in mark_buffer_dirty_inode / sync_mapping_buffers

write to 0xffff88813458af60 of 8 bytes by task 25095 on cpu 0:
 __remove_assoc_queue fs/buffer.c:481 [inline]
 fsync_buffers_list fs/buffer.c:688 [inline]
 sync_mapping_buffers+0x175/0x8d0 fs/buffer.c:548
 ext4_fsync_nojournal fs/ext4/fsync.c:86 [inline]
 ext4_sync_file+0x286/0x670 fs/ext4/fsync.c:170
 vfs_fsync_range+0x107/0x120 fs/sync.c:200
 generic_write_sync include/linux/fs.h:2955 [inline]
 ext4_buffered_write_iter+0x3af/0x400 fs/ext4/file.c:277
 ext4_file_write_iter+0x2e7/0x11f0
 call_write_iter include/linux/fs.h:2163 [inline]
 do_iter_readv_writev+0x2de/0x380 fs/read_write.c:729
 do_iter_write+0x192/0x5c0 fs/read_write.c:855
 vfs_iter_write+0x4c/0x70 fs/read_write.c:896
 iter_file_splice_write+0x43a/0x790 fs/splice.c:689
 do_splice_from fs/splice.c:767 [inline]
 direct_splice_actor+0x80/0xa0 fs/splice.c:936
 splice_direct_to_actor+0x345/0x650 fs/splice.c:891
 do_splice_direct+0x106/0x190 fs/splice.c:979
 do_sendfile+0x63e/0xbb0 fs/read_write.c:1249
 __do_sys_sendfile64 fs/read_write.c:1314 [inline]
 __se_sys_sendfile64 fs/read_write.c:1300 [inline]
 __x64_sys_sendfile64+0x102/0x140 fs/read_write.c:1300
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x44/0xa0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae

read to 0xffff88813458af60 of 8 bytes by task 25085 on cpu 1:
 mark_buffer_dirty_inode+0x92/0x1d0 fs/buffer.c:581
 __ext4_handle_dirty_metadata+0x1a7/0x5a0 fs/ext4/ext4_jbd2.c:376
 __ext4_ext_dirty fs/ext4/extents.c:166 [inline]
 ext4_ext_insert_extent+0x1ddc/0x2d90 fs/ext4/extents.c:2138
 ext4_ext_map_blocks+0x1714/0x1ff0 fs/ext4/extents.c:4271
 ext4_map_blocks+0x71e/0xf00 fs/ext4/inode.c:637
 ext4_iomap_alloc fs/ext4/inode.c:3368 [inline]
 ext4_iomap_begin+0x4b0/0x630 fs/ext4/inode.c:3418
 iomap_iter+0x39c/0x470 fs/iomap/iter.c:74
 __iomap_dio_rw+0xbe3/0x1010 fs/iomap/direct-io.c:568
 iomap_dio_rw+0x30/0x70 fs/iomap/direct-io.c:649
 ext4_dio_write_iter fs/ext4/file.c:568 [inline]
 ext4_file_write_iter+0xa59/0x11f0 fs/ext4/file.c:678
 call_write_iter include/linux/fs.h:2163 [inline]
 do_iter_readv_writev+0x2de/0x380 fs/read_write.c:729
 do_iter_write+0x192/0x5c0 fs/read_write.c:855
 vfs_iter_write+0x4c/0x70 fs/read_write.c:896
 iter_file_splice_write+0x43a/0x790 fs/splice.c:689
 do_splice_from fs/splice.c:767 [inline]
 direct_splice_actor+0x80/0xa0 fs/splice.c:936
 splice_direct_to_actor+0x345/0x650 fs/splice.c:891
 do_splice_direct+0x106/0x190 fs/splice.c:979
 do_sendfile+0x63e/0xbb0 fs/read_write.c:1249
 __do_sys_sendfile64 fs/read_write.c:1314 [inline]
 __se_sys_sendfile64 fs/read_write.c:1300 [inline]
 __x64_sys_sendfile64+0x102/0x140 fs/read_write.c:1300
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x44/0xa0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae

value changed: 0xffff88813466b440 -> 0x0000000000000000

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 25085 Comm: syz-executor.2 Not tainted 5.15.0-rc4-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
==================================================================
syz-executor.2 (25085) used greatest stack depth: 9904 bytes left