loop0: detected capacity change from 0 to 8192
==================================================================
BUG: KCSAN: data-race in mark_buffer_dirty_inode / sync_mapping_buffers

write to 0xffff888106ae7670 of 8 bytes by task 21540 on cpu 1:
 __remove_assoc_queue fs/buffer.c:516 [inline]
 fsync_buffers_list fs/buffer.c:791 [inline]
 sync_mapping_buffers+0x162/0x7e0 fs/buffer.c:577
 fat_file_fsync+0xad/0x100 fs/fat/file.c:195
 vfs_fsync_range+0x122/0x140 fs/sync.c:188
 generic_write_sync include/linux/fs.h:2794 [inline]
 generic_file_write_iter+0x191/0x1d0 mm/filemap.c:4140
 iter_file_splice_write+0x5e6/0x970 fs/splice.c:743
 do_splice_from fs/splice.c:941 [inline]
 direct_splice_actor+0x16c/0x2c0 fs/splice.c:1164
 splice_direct_to_actor+0x305/0x670 fs/splice.c:1108
 do_splice_direct_actor fs/splice.c:1207 [inline]
 do_splice_direct+0xd7/0x150 fs/splice.c:1233
 do_sendfile+0x3ab/0x960 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
 x64_sys_call+0x2c9f/0x2d70 arch/x86/include/generated/asm/syscalls_64.h:41
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xc9/0x1c0 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff888106ae7670 of 8 bytes by task 21534 on cpu 0:
 mark_buffer_dirty_inode+0x96/0x1c0 fs/buffer.c:680
 fat_mirror_bhs+0x241/0x330 fs/fat/fatent.c:398
 fat_ent_write+0xcc/0xe0 fs/fat/fatent.c:423
 fat_chain_add+0x15f/0x400 fs/fat/misc.c:136
 fat_add_cluster fs/fat/inode.c:113 [inline]
 __fat_get_block fs/fat/inode.c:155 [inline]
 fat_get_block+0x46b/0x5e0 fs/fat/inode.c:190
 __block_write_begin_int+0x417/0xfa0 fs/buffer.c:2128
 __block_write_begin fs/buffer.c:2177 [inline]
 block_write_begin+0x7b/0x170 fs/buffer.c:2236
 cont_write_begin+0x486/0x6b0 fs/buffer.c:2590
 fat_write_begin+0x61/0xf0 fs/fat/inode.c:230
 cont_expand_zero fs/buffer.c:2517 [inline]
 cont_write_begin+0x186/0x6b0 fs/buffer.c:2580
 fat_write_begin+0x61/0xf0 fs/fat/inode.c:230
 generic_cont_expand_simple+0xaa/0x150 fs/buffer.c:2481
 fat_cont_expand+0x3a/0x160 fs/fat/file.c:223
 fat_setattr+0x2aa/0x840 fs/fat/file.c:513
 notify_change+0x814/0x8a0 fs/attr.c:497
 do_truncate fs/open.c:65 [inline]
 do_ftruncate+0x3e1/0x470 fs/open.c:181
 do_sys_ftruncate fs/open.c:199 [inline]
 __do_sys_ftruncate fs/open.c:207 [inline]
 __se_sys_ftruncate fs/open.c:205 [inline]
 __x64_sys_ftruncate+0x6a/0xc0 fs/open.c:205
 x64_sys_call+0x1f60/0x2d70 arch/x86/include/generated/asm/syscalls_64.h:78
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xc9/0x1c0 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0xffff888106b56670 -> 0x0000000000000000

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 21534 Comm: syz-executor.0 Tainted: G        W          6.10.0-rc3-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/02/2024
==================================================================