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BUG: KCSAN: data-race in mark_buffer_dirty_inode / mark_buffer_dirty_inode

write to 0xffff88810048d538 of 8 bytes by task 30664 on cpu 1:
 mark_buffer_dirty_inode+0x190/0x1c0 fs/buffer.c:691
 fat_mirror_bhs+0x212/0x310 fs/fat/fatent.c:398
 fat_alloc_clusters+0x973/0xa60 fs/fat/fatent.c:543
 fat_add_cluster fs/fat/inode.c:108 [inline]
 __fat_get_block fs/fat/inode.c:155 [inline]
 fat_get_block+0x25c/0x5e0 fs/fat/inode.c:190
 __block_write_begin_int+0x3c0/0xf20 fs/buffer.c:2107
 __block_write_begin fs/buffer.c:2157 [inline]
 block_write_begin+0x7b/0x170 fs/buffer.c:2216
 cont_write_begin+0x479/0x690 fs/buffer.c:2573
 fat_write_begin+0x61/0xf0 fs/fat/inode.c:230
 generic_perform_write+0x1c9/0x410 mm/filemap.c:3945
 __generic_file_write_iter+0xa1/0x120 mm/filemap.c:4040
 generic_file_write_iter+0x7d/0x1c0 mm/filemap.c:4066
 call_write_iter include/linux/fs.h:1985 [inline]
 new_sync_write fs/read_write.c:491 [inline]
 vfs_write+0x4ab/0x7d0 fs/read_write.c:584
 ksys_write+0xeb/0x1a0 fs/read_write.c:637
 __do_sys_write fs/read_write.c:649 [inline]
 __se_sys_write fs/read_write.c:646 [inline]
 __x64_sys_write+0x42/0x50 fs/read_write.c:646
 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 0xffff88810048d538 of 8 bytes by task 30642 on cpu 0:
 mark_buffer_dirty_inode+0x96/0x1c0 fs/buffer.c:687
 fat_mirror_bhs+0x212/0x310 fs/fat/fatent.c:398
 fat_alloc_clusters+0x973/0xa60 fs/fat/fatent.c:543
 fat_add_cluster fs/fat/inode.c:108 [inline]
 __fat_get_block fs/fat/inode.c:155 [inline]
 fat_get_block+0x25c/0x5e0 fs/fat/inode.c:190
 __block_write_begin_int+0x3c0/0xf20 fs/buffer.c:2107
 __block_write_begin fs/buffer.c:2157 [inline]
 block_write_begin+0x7b/0x170 fs/buffer.c:2216
 cont_write_begin+0x479/0x690 fs/buffer.c:2573
 fat_write_begin+0x61/0xf0 fs/fat/inode.c:230
 generic_perform_write+0x1c9/0x410 mm/filemap.c:3945
 __generic_file_write_iter+0xa1/0x120 mm/filemap.c:4040
 generic_file_write_iter+0x7d/0x1c0 mm/filemap.c:4066
 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:1322 [inline]
 __se_sys_sendfile64 fs/read_write.c:1308 [inline]
 __x64_sys_sendfile64+0x110/0x150 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

value changed: 0x0000000000000000 -> 0xffff8881084df8a0

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 30642 Comm: syz-executor.2 Not tainted 6.5.0-syzkaller-09276-g99d99825fc07 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/26/2023
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