Hi David,
On 07/22/2015 02:41 AM, David Rientjes wrote:
> munmap(2) will fail with an errno of EINVAL for hugetlb memory if the
> length is not a multiple of the underlying page size.
>
> Documentation/vm/hugetlbpage.txt was updated to specify this behavior
> since Linux 4.1 in commit 80d6b94bd69a ("mm, doc: cleanup and clarify
> munmap behavior for hugetlb memory").
>
> Signed-off-by: David Rientjes <rientjes@xxxxxxxxxx>
> ---
> man2/mmap.2 | 4 ++++
> 1 file changed, 4 insertions(+)
>
> diff --git a/man2/mmap.2 b/man2/mmap.2
> --- a/man2/mmap.2
> +++ b/man2/mmap.2
> @@ -383,6 +383,10 @@ All pages containing a part
> of the indicated range are unmapped, and subsequent references
> to these pages will generate
> .BR SIGSEGV .
> +An exception is when the underlying memory is not of the native page
> +size, such as hugetlb page sizes, whereas
> +.I length
> +must be a multiple of the underlying page size.
> It is not an error if the
> indicated range does not contain any mapped pages.
> .SS Timestamps changes for file-backed mappings
I'm struggling a bit to understand your text. Is the point this:
If we have a hugetlb area, then the munmap() length
must be a multiple of the page size.
?
Are there any requirements about 'addr'? Must it also me huge-page-aligned?
Thanks,
Michael
--
Michael Kerrisk
Linux man-pages maintainer; http://www.kernel.org/doc/man-pages/
Linux/UNIX System Programming Training: http://man7.org/training/
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