syzbot

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BUG: KCSAN: data-race in _copy_to_iter / fat32_ent_put

write to 0xffff88811a6b2084 of 4 bytes by task 19932 on cpu 0:
 fat32_ent_put+0x54/0x90 fs/fat/fatent.c:191
 fat_alloc_clusters+0x47d/0xa80 fs/fat/fatent.c:503
 fat_add_cluster+0x43/0xd0 fs/fat/inode.c:108
 fat_fallocate+0x125/0x1c0 fs/fat/file.c:292
 vfs_fallocate+0x355/0x3d0 fs/open.c:323
 do_vfs_ioctl+0x12cf/0x1390 fs/ioctl.c:849
 __do_sys_ioctl fs/ioctl.c:868 [inline]
 __se_sys_ioctl+0x83/0x140 fs/ioctl.c:856
 __x64_sys_ioctl+0x3f/0x50 fs/ioctl.c:856
 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 0xffff88811a6b2000 of 512 bytes by task 19919 on cpu 1:
 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: 1 PID: 19919 Comm: udevd Tainted: G        W          6.2.0-rc6-syzkaller-00011-gc0b67534c95c-dirty #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/12/2023
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I/O error, dev loop4, sector 0 op 0x0:(READ) flags 0x80700 phys_seg 1 prio class 2