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BUG: KCSAN: data-race in _copy_to_iter / fat16_ent_put

write to 0xffff88812079d23a of 2 bytes by task 24336 on cpu 1:
 fat16_ent_put+0x24/0x50 fs/fat/fatent.c:183
 fat_ent_write+0x5e/0xd0 fs/fat/fatent.c:417
 fat_chain_add+0x15b/0x410 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+0x486/0x600 fs/fat/inode.c:190
 __block_write_begin_int+0x33d/0xc50 fs/buffer.c:1991
 __block_write_begin fs/buffer.c:2041 [inline]
 block_write_begin+0x73/0x170 fs/buffer.c:2102
 cont_write_begin+0x3f1/0x520 fs/buffer.c:2456
 fat_write_begin+0x5d/0xe0 fs/fat/inode.c:230
 cont_expand_zero fs/buffer.c:2416 [inline]
 cont_write_begin+0x449/0x520 fs/buffer.c:2446
 fat_write_begin+0x5d/0xe0 fs/fat/inode.c:230
 generic_cont_expand_simple+0xa9/0x140 fs/buffer.c:2347
 fat_cont_expand+0x3a/0x160 fs/fat/file.c:223
 fat_setattr+0x36f/0x9f0 fs/fat/file.c:513
 notify_change+0xa5c/0xad0 fs/attr.c:482
 do_truncate+0xfa/0x140 fs/open.c:65
 do_sys_ftruncate+0x28a/0x380 fs/open.c:193
 __do_sys_ftruncate fs/open.c:204 [inline]
 __se_sys_ftruncate fs/open.c:202 [inline]
 __x64_sys_ftruncate+0x2f/0x40 fs/open.c:202
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x2b/0x70 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd

read to 0xffff88812079d000 of 1377 bytes by task 18140 on cpu 0:
 instrument_copy_to_user include/linux/instrumented.h:120 [inline]
 copyout lib/iov_iter.c:169 [inline]
 _copy_to_iter+0x135/0x910 lib/iov_iter.c:529
 copy_page_to_iter+0x31b/0x450 lib/iov_iter.c:727
 copy_folio_to_iter include/linux/uio.h:172 [inline]
 filemap_read+0x11db/0x1510 mm/filemap.c:2745
 blkdev_read_iter+0x2c6/0x370 block/fops.c:591
 call_read_iter include/linux/fs.h:2183 [inline]
 new_sync_read fs/read_write.c:389 [inline]
 vfs_read+0x3a5/0x560 fs/read_write.c:470
 ksys_read+0xe8/0x1a0 fs/read_write.c:613
 __do_sys_read fs/read_write.c:623 [inline]
 __se_sys_read fs/read_write.c:621 [inline]
 __x64_sys_read+0x3e/0x50 fs/read_write.c:621
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x2b/0x70 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 18140 Comm: udevd Not tainted 6.2.0-rc4-syzkaller-00041-gc1649ec55708-dirty #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/12/2023
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