loop1: detected capacity change from 0 to 8192
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BUG: KCSAN: data-race in mark_buffer_dirty_inode / sync_mapping_buffers

write to 0xffff888106771dc0 of 8 bytes by task 22435 on cpu 0:
 __remove_assoc_queue fs/buffer.c:523 [inline]
 fsync_buffers_list fs/buffer.c:791 [inline]
 sync_mapping_buffers+0x165/0x7d0 fs/buffer.c:584
 fat_file_fsync+0xad/0x100 fs/fat/file.c:195
 vfs_fsync_range+0x111/0x120 fs/sync.c:188
 generic_write_sync include/linux/fs.h:2584 [inline]
 generic_file_write_iter+0x191/0x1c0 mm/filemap.c:4094
 do_iter_write+0x4b4/0x7b0 fs/read_write.c:860
 vfs_iter_write+0x56/0x70 fs/read_write.c:901
 iter_file_splice_write+0x462/0x7e0 fs/splice.c:736
 do_splice_from fs/splice.c:933 [inline]
 direct_splice_actor+0x8a/0xb0 fs/splice.c:1142
 splice_direct_to_actor+0x31d/0x690 fs/splice.c:1088
 do_splice_direct+0x10d/0x190 fs/splice.c:1194
 do_sendfile+0x3b6/0x9a0 fs/read_write.c:1254
 __do_sys_sendfile64 fs/read_write.c:1316 [inline]
 __se_sys_sendfile64 fs/read_write.c:1308 [inline]
 __x64_sys_sendfile64+0xbd/0x150 fs/read_write.c:1308
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd

read to 0xffff888106771dc0 of 8 bytes by task 22424 on cpu 1:
 mark_buffer_dirty_inode+0x96/0x1c0 fs/buffer.c:687
 fat16_ent_put+0x4f/0x60 fs/fat/fatent.c:184
 fat_alloc_clusters+0x4b5/0xa60 fs/fat/fatent.c:503
 fat_add_cluster+0x47/0xd0 fs/fat/inode.c:108
 fat_fallocate+0x129/0x1d0 fs/fat/file.c:292
 vfs_fallocate+0x378/0x3e0 fs/open.c:324
 do_vfs_ioctl+0x12e6/0x13a0 fs/ioctl.c:850
 __do_sys_ioctl fs/ioctl.c:869 [inline]
 __se_sys_ioctl+0x81/0x140 fs/ioctl.c:857
 __x64_sys_ioctl+0x43/0x50 fs/ioctl.c:857
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd

value changed: 0xffff8881067c3598 -> 0x0000000000000000

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 22424 Comm: syz-executor.1 Not tainted 6.6.0-rc7-syzkaller-00041-g611da07b89fd #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/06/2023
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