When using mremap() with MREMAP_FIXED and bad parameters, mremap()
returns EINVAL, which is expected; but it also unmaps existing regions
at 'new_address', which surprised me. I had expected that on EINVAL,
mappings at 'new_address' would remain unmodified.
The current behavior is reasonable, but it was surprising to me, so it might
be surprising to others. The man page DESCRIPTION currently says:
"Any previous mapping at the address range specified by new_address
and new_size is unmapped."
It would be clearer to me if it also said something like:
"Previous mappings may be unmapped even if mremap() returns an error."
And/or if ERRORS said something about this behavior.
A sample patch for man2/mremap.2 is attached.
Attachment:
mremap.2.patch
Description: mremap.2.patch
