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

["Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>]

Andrew Morton <akpm@linux-foundation.org> writes:

> 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).

3.10_rc5 is less strict. Also Naoya Horiguchi updated that relevant
changes to libhugetlbfs test is also posted at 

http://www.mail-archive.com/libhugetlbfs-devel@lists.sourceforge.net/msg13317.html

-aneesh

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