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

Andrew Morton [off-list ref] writes:

On Wed, 12 Jun 2013 17:46:16 +0530 "Aneesh Kumar K.V" [off-list ref] wrote:

quoted

quoted

From: Naoya Horiguchi <redacted>
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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