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Date: Sun, 3 Feb 2013 23:17:09 -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 v2 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 a 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. I would actually like to get Andrea's attention on this one, as I can't explain how munlock_vma_page() is safe against racing with split_huge_page(). Note that patches 1-2 are logically independent of patch 3, so if the discussion of patch 3 takes too long I would ask Andrew to consider merging patches 1-2 first. Changes since v1: - 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. Michel Lespinasse (3): fix 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 | 2 +- include/linux/mm.h | 24 +++++++++++++++++------- mm/hugetlb.c | 8 ++++---- mm/internal.h | 2 +- mm/memory.c | 43 +++++++++++++++++++++++++++++-------------- mm/mlock.c | 34 ++++++++++++++++++++++------------ mm/nommu.c | 6 ++++-- 7 files changed, 78 insertions(+), 41 deletions(-) -- 1.8.1 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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