Re: [Bug 56881] New: MAP_HUGETLB mmap fails for certain sizes

[Andrew Morton <akpm@linux-foundation.org>]

On Wed, 12 Jun 2013 17:46:16 +0530 "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com> wrote:

> > From: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
> > Date: Wed, 24 Apr 2013 16:44:19 -0400
> > Subject: [PATCH] hugetlbfs: fix mmap failure in unaligned size request
> >
> > As reported in https://bugzilla.kernel.org/show_bug.cgi?id=56881, current
> > kernel returns -EINVAL unless a given mmap length is "almost" hugepage
> > aligned. This is because in sys_mmap_pgoff() the given length is passed to
> > vm_mmap_pgoff() as it is without being aligned with hugepage boundary.
> >
> > This is a regression introduced in commit 40716e29243d "hugetlbfs: fix
> > alignment of huge page requests", where alignment code is pushed into
> > hugetlb_file_setup() and the variable len in caller side is not changed.
> >
> > To fix this, this patch partially reverts that commit, and changes
> > the type of parameter size from size_t to (size_t *) in order to
> > align the size in caller side.
> 
> After the change af73e4d9506d3b797509f3c030e7dcd554f7d9c4 we have
> alignment related failures in libhugetlbfs test suite. misalign test
> fails with 3.10-rc5, while it works with 3.9.

What does this mean.  Is 3.10-rc5 more strict, or less strict?

If "less strict" then that's expected and old userspace should be OK
with the change and the test should be updated (sorry).

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