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authorAdam Litke <agl@us.ibm.com>2007-11-14 19:59:38 -0500
committerLinus Torvalds <torvalds@woody.linux-foundation.org>2007-11-14 21:45:40 -0500
commitc79fb75e5a514a5a35f22c229042aa29f4237e3a (patch)
tree012e5610e814ed938628af84ffa7c4775db113e2 /Documentation/sgi-ioc4.txt
parent348ea204cc23cda35faf962414b674c57da647d7 (diff)
hugetlb: fix quota management for private mappings
The hugetlbfs quota management system was never taught to handle MAP_PRIVATE mappings when that support was added. Currently, quota is debited at page instantiation and credited at file truncation. This approach works correctly for shared pages but is incomplete for private pages. In addition to hugetlb_no_page(), private pages can be instantiated by hugetlb_cow(); but this function does not respect quotas. Private huge pages are treated very much like normal, anonymous pages. They are not "backed" by the hugetlbfs file and are not stored in the mapping's radix tree. This means that private pages are invisible to truncate_hugepages() so that function will not credit the quota. This patch (based on a prototype provided by Ken Chen) moves quota crediting for all pages into free_huge_page(). page->private is used to store a pointer to the mapping to which this page belongs. This is used to credit quota on the appropriate hugetlbfs instance. Signed-off-by: Adam Litke <agl@us.ibm.com> Cc: Ken Chen <kenchen@google.com> Cc: Ken Chen <kenchen@google.com> Cc: Andy Whitcroft <apw@shadowen.org> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: David Gibson <hermes@gibson.dropbear.id.au> Cc: William Lee Irwin III <wli@holomorphy.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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