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

write to 0xffff888107159330 of 8 bytes by task 3465 on cpu 0:
 __remove_assoc_queue fs/buffer.c:514 [inline]
 fsync_buffers_list fs/buffer.c:788 [inline]
 sync_mapping_buffers+0x156/0x7b0 fs/buffer.c:575
 fat_file_fsync+0xa7/0x100 fs/fat/file.c:195
 vfs_fsync_range+0x116/0x130 fs/sync.c:188
 generic_write_sync include/linux/fs.h:2870 [inline]
 generic_file_write_iter+0x185/0x1c0 mm/filemap.c:4181
 new_sync_write fs/read_write.c:590 [inline]
 vfs_write+0x76a/0x910 fs/read_write.c:683
 ksys_write+0xeb/0x1b0 fs/read_write.c:736
 __do_sys_write fs/read_write.c:748 [inline]
 __se_sys_write fs/read_write.c:745 [inline]
 __x64_sys_write+0x42/0x50 fs/read_write.c:745
 x64_sys_call+0x27dd/0x2d60 arch/x86/include/generated/asm/syscalls_64.h:2
 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 0xffff888107159330 of 8 bytes by task 3466 on cpu 1:
 mark_buffer_dirty_inode+0x96/0x1c0 fs/buffer.c:678
 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:112 [inline]
 __fat_get_block fs/fat/inode.c:154 [inline]
 fat_get_block+0x46b/0x5e0 fs/fat/inode.c:189
 __block_write_begin_int+0x417/0xfa0 fs/buffer.c:2121
 block_write_begin fs/buffer.c:2231 [inline]
 cont_write_begin+0x546/0x860 fs/buffer.c:2582
 fat_write_begin+0x51/0xe0 fs/fat/inode.c:228
 generic_perform_write+0x1a8/0x4a0 mm/filemap.c:4050
 __generic_file_write_iter+0xa1/0x120 mm/filemap.c:4151
 generic_file_write_iter+0x77/0x1c0 mm/filemap.c:4177
 __kernel_write_iter+0x24b/0x4e0 fs/read_write.c:616
 __kernel_write+0x90/0xc0 fs/read_write.c:636
 __dump_emit+0xd1/0x2a0 fs/coredump.c:861
 dump_emit+0x82/0xa0 fs/coredump.c:913
 writenote+0x10a/0x190 fs/binfmt_elf.c:1463
 write_note_info fs/binfmt_elf.c:1941 [inline]
 elf_core_dump+0x1b13/0x2360 fs/binfmt_elf.c:2122
 do_coredump+0x186d/0x20a0 fs/coredump.c:800
 get_signal+0xdad/0x1100 kernel/signal.c:2904
 arch_do_signal_or_restart+0x95/0x4b0 arch/x86/kernel/signal.c:337
 exit_to_user_mode_loop kernel/entry/common.c:111 [inline]
 exit_to_user_mode_prepare include/linux/entry-common.h:328 [inline]
 irqentry_exit_to_user_mode+0x9a/0x130 kernel/entry/common.c:231
 irqentry_exit+0x12/0x50 kernel/entry/common.c:334
 exc_general_protection+0x33d/0x4d0 arch/x86/kernel/traps.c:693
 asm_exc_general_protection+0x26/0x30 arch/x86/include/asm/idtentry.h:617

value changed: 0xffff88810711d708 -> 0x0000000000000000

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 3466 Comm: syz.2.16 Not tainted 6.11.0-syzkaller-08829-gaf9c191ac2a0 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/06/2024
==================================================================
coredump: 14(syz.2.16): Error writing out the process memory
coredump: 14(syz.2.16): written to core: VMAs: 29, size 89030656; core: 17070 bytes, pos 40960
syz.2.16 (3466) used greatest stack depth: 9160 bytes left