linux-kernel - [PATCH v3 0/3] fixes for large mm_populate() and munlock() operations

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Date:	Fri,  8 Feb 2013 16:03:54 -0800
From:	Michel Lespinasse <walken@...gle.com>
To:	Andrea Arcangeli <aarcange@...hat.com>,
	Rik van Riel <riel@...hat.com>, Mel Gorman <mgorman@...e.de>,
	Hugh Dickins <hughd@...gle.com>,
	Andrew Morton <akpm@...ux-foundation.org>, linux-mm@...ck.org
Cc:	linux-kernel@...r.kernel.org
Subject: [PATCH v3 0/3] fixes for large mm_populate() and munlock() operations

These 3 changes are to improve the handling of large mm_populate and
munlock operations. They apply on top of mmotm (in particular, they
depend on both my prior mm_populate work and Kirill's "thp: avoid
dumping huge zero page" change).

- Patch 1 fixes an integer overflow issue when populating 2^32 pages.
  The nr_pages argument to get_user_pages would overflow, resulting in 0
  pages being processed per iteration. I am proposing to simply convert
  the nr_pages argument to an unsigned long.

- Patch 2 accelerates populating regions with THP pages. get_user_pages()
  can increment the address by a huge page size in this case instead of
  a small page size, and avoid repeated mm->page_table_lock acquisitions.
  This fixes an issue reported by Roman Dubtsov where populating regions
  via mmap MAP_POPULATE was significantly slower than doing so by
  touching pages from userspace.

- Patch 3 is a similar acceleration for the munlock case.

Changes between v1 and v2:

- Andrew accepted patch 1 into his -mm tree but suggested the nr_pages
  argument type should actually be unsigned long; I am sending this as
  a "fix" for the previous patch 1 to be collapsed over the previous one.

- In patch 2, I am adding a separate follow_page_mask() function so that
  the callers to the original follow_page() don't have to be modified to
  ignore the returned page_mask (following another suggestion from Andrew).
  Also the page_mask argument type was changed to unsigned int.

- In patch 3, I similarly changed the page_mask values to unsigned int.

Changes between v2 and v3:

- In patch 1, updated mm/nommu.c to match the updated gup function prototype
  and avoid breaking the nommu build.

- In patch 1, removed incorrect VM_BUG_ON in mm/mlock.c

- In patch 3, fixed munlock_vma_page() to return a page mask as expected
  by munlock_vma_pages_range() instead of a number of pages.

Michel Lespinasse (3):
  mm: use long type for page counts in mm_populate() and get_user_pages()
  mm: accelerate mm_populate() treatment of THP pages
  mm: accelerate munlock() treatment of THP pages

 include/linux/hugetlb.h |  6 +++---
 include/linux/mm.h      | 28 +++++++++++++++++++---------
 mm/hugetlb.c            | 12 ++++++------
 mm/internal.h           |  2 +-
 mm/memory.c             | 49 ++++++++++++++++++++++++++++++++-----------------
 mm/mlock.c              | 38 +++++++++++++++++++++++++-------------
 mm/nommu.c              | 21 ++++++++++++---------
 7 files changed, 98 insertions(+), 58 deletions(-)

-- 
1.8.1
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