Re: [patch 1/2] mm, doc: cleanup and clarify munmap behavior for hugetlb memory

From: David Rientjes
Date: Thu Apr 02 2015 - 18:41:09 EST


On Sun, 29 Mar 2015, Hugh Dickins wrote:

> > munmap(2) of hugetlb memory requires a length that is hugepage aligned,
> > otherwise it may fail. Add this to the documentation.
>
> Thanks for taking this on, David. But although munmap(2) is the one
> Davide called out, it goes beyond that, doesn't it? To mprotect and
> madvise and ...
>

Yes, good point, munmap(2) isn't special in this case, the alignment to
the native page size of the platform should apply to madvise, mbind,
mincore, mlock, mprotect, remap_file_pages, etc.

I'd hesitate to compile any authoritative list on the behavior in
Documentation/vm/hugetlbpage.txt since it would exclude future extensions,
but I'll update it to be more inclusive of other mm syscalls rather than
specify only munmap(2).
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