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BUG: KCSAN: data-race in mark_buffer_dirty_inode / sync_mapping_buffers

write to 0xffff8881067e00c0 of 8 bytes by task 14502 on cpu 1:
 __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
 call_write_iter include/linux/fs.h:1956 [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 0xffff8881067e00c0 of 8 bytes by task 14464 on cpu 0:
 mark_buffer_dirty_inode+0x96/0x1c0 fs/buffer.c:687
 fat_mirror_bhs+0x212/0x310 fs/fat/fatent.c:398
 fat_ent_write+0xc6/0xe0 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+0x467/0x5e0 fs/fat/inode.c:190
 __block_write_begin_int+0x3c3/0xf50 fs/buffer.c:2120
 __block_write_begin fs/buffer.c:2169 [inline]
 block_write_begin+0x7b/0x170 fs/buffer.c:2228
 cont_write_begin+0x479/0x690 fs/buffer.c:2585
 fat_write_begin+0x61/0xf0 fs/fat/inode.c:230
 cont_expand_zero fs/buffer.c:2512 [inline]
 cont_write_begin+0x182/0x690 fs/buffer.c:2575
 fat_write_begin+0x61/0xf0 fs/fat/inode.c:230
 generic_cont_expand_simple+0xa7/0x140 fs/buffer.c:2476
 fat_cont_expand+0x3a/0x160 fs/fat/file.c:223
 fat_setattr+0x2a9/0x840 fs/fat/file.c:513
 notify_change+0x866/0x8e0 fs/attr.c:499
 do_truncate+0x116/0x150 fs/open.c:66
 do_sys_ftruncate+0x2ba/0x3b0 fs/open.c:194
 __do_sys_ftruncate fs/open.c:205 [inline]
 __se_sys_ftruncate fs/open.c:203 [inline]
 __x64_sys_ftruncate+0x33/0x40 fs/open.c:203
 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: 0xffff8881066d1d58 -> 0x0000000000000000

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 14464 Comm: syz-executor.5 Not tainted 6.6.0-rc6-syzkaller-00207-gc8045b4a33a5 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/06/2023
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