Commit f44b2dda authored May 19, 2016 by Joonsoo Kim Committed by Linus Torvalds May 19, 2016

mm/hugetlb: add same zone check in pfn_range_valid_gigantic()

This patchset deals with some problematic sites that iterate pfn ranges.

There is a system thats node's pfns are overlapped as follows:

  -----pfn-------->
  N0 N1 N2 N0 N1 N2

Therefore, we need to take care of this overlapping when iterating pfn
range.

I audit many iterating sites that uses pfn_valid(), pfn_valid_within(),
zone_start_pfn and etc.  and others looks safe to me.  This is a
preparation step for a new CMA implementation, ZONE_CMA
(https://lkml.org/lkml/2015/2/12/95

), because it would be easily
overlapped with other zones.  But, zone overlap check is also needed for
the general case so I send it separately.

This patch (of 5):

alloc_gigantic_page() uses alloc_contig_range() and this requires that
the requested range is in a single zone.  To satisfy this requirement,
add this check to pfn_range_valid_gigantic().

Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Rik van Riel <riel@redhat.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Laura Abbott <lauraa@codeaurora.org>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Marek Szyprowski <m.szyprowski@samsung.com>
Cc: Michal Nazarewicz <mina86@mina86.com>
Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>
Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

parent 1aa8aea5

mm/hugetlb.c

+6 −3

Original line number	Diff line number	Diff line
		@@ -1031,8 +1031,8 @@ static int __alloc_gigantic_page(unsigned long start_pfn,
		return alloc_contig_range(start_pfn, end_pfn, MIGRATE_MOVABLE);
		}

		static bool pfn_range_valid_gigantic(unsigned long start_pfn,
		unsigned long nr_pages)
		static bool pfn_range_valid_gigantic(struct zone *z,
		unsigned long start_pfn, unsigned long nr_pages)
		{
		unsigned long i, end_pfn = start_pfn + nr_pages;
		struct page *page;
		@@ -1043,6 +1043,9 @@ static bool pfn_range_valid_gigantic(unsigned long start_pfn,

		page = pfn_to_page(i);

		if (page_zone(page) != z)
		return false;

		if (PageReserved(page))
		return false;

		@@ -1075,7 +1078,7 @@ static struct page *alloc_gigantic_page(int nid, unsigned int order)

		pfn = ALIGN(z->zone_start_pfn, nr_pages);
		while (zone_spans_last_pfn(z, pfn, nr_pages)) {
		if (pfn_range_valid_gigantic(pfn, nr_pages)) {
		if (pfn_range_valid_gigantic(z, pfn, nr_pages)) {
		/*
		* We release the zone lock here because
		* alloc_contig_range() will also lock the zone

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