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authorKOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>2008-10-18 20:27:10 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2008-10-20 08:52:32 -0700
commit4b2e38ad703541f7845c2d766426148b8d1aa329 (patch)
treeaaafbec5325d15c38c382c655120fb6492c11f82 /mm/thrash.c
parente575f111dc0f27044e170580e7de50985ab3e011 (diff)
hugepage: support ZERO_PAGE()
Presently hugepage doesn't use zero page at all because zero page is only used for coredumping and hugepage can't core dump. However we have now implemented hugepage coredumping. Therefore we should implement the zero page of hugepage. Implementation note: o Why do we only check VM_SHARED for zero page? normal page checked as .. static inline int use_zero_page(struct vm_area_struct *vma) { if (vma->vm_flags & (VM_LOCKED | VM_SHARED)) return 0; return !vma->vm_ops || !vma->vm_ops->fault; } First, hugepages are never mlock()ed. We aren't concerned with VM_LOCKED. Second, hugetlbfs is a pseudo filesystem, not a real filesystem and it doesn't have any file backing. Thus ops->fault checking is meaningless. o Why don't we use zero page if !pte. !pte indicate {pud, pmd} doesn't exist or some error happened. So we shouldn't return zero page if any error occurred. Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Adam Litke <agl@us.ibm.com> Cc: Hugh Dickins <hugh@veritas.com> Cc: Kawai Hidehiro <hidehiro.kawai.ez@hitachi.com> Cc: Mel Gorman <mel@skynet.ie> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/thrash.c')
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