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authorHugh Dickins <hugh@veritas.com>2006-02-14 13:52:59 -0800
committerLinus Torvalds <torvalds@g5.osdl.org>2006-02-14 16:09:33 -0800
commitd98c7a09843621f1b145ca5ae8ed03ff04085edb (patch)
tree764b943efb177ca506fad61a63bb9e8cbf56a3a7 /kernel
parent41d78ba55037468e6c86c53e3076d1a74841de39 (diff)
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[PATCH] compound page: default destructor
Somehow I imagined that calling a NULL destructor would free a compound page rather than oopsing. No, we must supply a default destructor, __free_pages_ok using the order noted by prep_compound_page. hugetlb can still replace this as before with its own free_huge_page pointer. The case that needs this is not common: rarely does put_compound_page's put_page_testzero bring the count down to 0. But if get_user_pages is applied to some part of a compound page, without immediate release (e.g. AIO or Infiniband), then it's possible for its put_page to come after the containing vma has been unmapped and the driver done its free_pages. That's just the kind of case compound pages are supposed to be guarding against (but Nick points out, nor did PageReserved handle this right). Signed-off-by: Hugh Dickins <hugh@veritas.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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