On 07/07/2017 01:45 AM, Anshuman Khandual wrote: > On 07/06/2017 09:47 PM, Mike Kravetz wrote: >> The mremap system call has the ability to 'mirror' parts of an existing >> mapping. To do so, it creates a new mapping that maps the same pages as >> the original mapping, just at a different virtual address. This >> functionality has existed since at least the 2.6 kernel. >> >> This patch simply adds a new flag to mremap which will make this >> functionality part of the API. It maintains backward compatibility with >> the existing way of requesting mirroring (old_size == 0). >> >> If this new MREMAP_MIRROR flag is specified, then new_size must equal >> old_size. In addition, the MREMAP_MAYMOVE flag must be specified. > > Yeah it all looks good. But why is this requirement that if > MREMAP_MAYMOVE is specified then old_size and new_size must > be equal.
No real reason. I just wanted to clearly separate the new interface from the old. On second thought, it would be better to require old_size == 0 as in the legacy interface. -- Mike Kravetz
