Files uploaded into top folder can't be cut, can cause XWiki crash

Have a file someone uploaded to the File Manager top folder (48 mb mp4 file).  Trying to move it to appropriate subfolder.  This doesn't work - appears to leave two copies, one in destination folder, one in source (top) folder.

Attempt to delete the apparently left-behind file in top folder, and usually the JVM crashes with a memory error, allocating an insane amount of memory:

OpenJDK 64-Bit Server VM warning: INFO: os::commit_memory(0x00000007b044f000, 133816320, 0) failed; error='Cannot allocate memory' (errno=12)
#

1. There is insufficient memory for the Java Runtime Environment to continue.
2. Native memory allocation (mmap) failed to map 133816320 bytes for committing reserved memory.
3. An error report file with more information is saved as:
4. /tmp/hs_err_pid2280.log

Can sometimes work around by copying the files, then deleting.  But customers using my XWiki can easily crash the system.  And there is no apparent way to prohibit uploads to the top folder.