The patch titled hugepage: support ZERO_PAGE() has been added to the -mm tree. Its filename is hugepage-support-zero_page.patch Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's *** Remember to use Documentation/SubmitChecklist when testing your code *** See http://userweb.kernel.org/~akpm/added-to-mm.txt to find out what to do about this The current -mm tree may be found at http://userweb.kernel.org/~akpm/mmotm/ ------------------------------------------------------ Subject: hugepage: support ZERO_PAGE() From: KOSAKI Motohiro <kosaki.motohiro@xxxxxxxxxxxxxx> 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@xxxxxxxxxxxxxx> Cc: Adam Litke <agl@xxxxxxxxxx> Cc: Hugh Dickins <hugh@xxxxxxxxxxx> Cc: Kawai Hidehiro <hidehiro.kawai.ez@xxxxxxxxxxx> Cc: Mel Gorman <mel@xxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- mm/hugetlb.c | 22 +++++++++++++++++++--- 1 file changed, 19 insertions(+), 3 deletions(-) diff -puN mm/hugetlb.c~hugepage-support-zero_page mm/hugetlb.c --- a/mm/hugetlb.c~hugepage-support-zero_page +++ a/mm/hugetlb.c @@ -2071,6 +2071,14 @@ follow_huge_pud(struct mm_struct *mm, un return NULL; } +static int huge_zeropage_ok(pte_t *ptep, int write, int shared) +{ + if (!ptep || write || shared) + return 0; + else + return huge_pte_none(huge_ptep_get(ptep)); +} + int follow_hugetlb_page(struct mm_struct *mm, struct vm_area_struct *vma, struct page **pages, struct vm_area_struct **vmas, unsigned long *position, int *length, int i, @@ -2080,6 +2088,8 @@ int follow_hugetlb_page(struct mm_struct unsigned long vaddr = *position; int remainder = *length; struct hstate *h = hstate_vma(vma); + int zeropage_ok = 0; + int shared = vma->vm_flags & VM_SHARED; spin_lock(&mm->page_table_lock); while (vaddr < vma->vm_end && remainder) { @@ -2092,8 +2102,11 @@ int follow_hugetlb_page(struct mm_struct * first, for the page indexing below to work. */ pte = huge_pte_offset(mm, vaddr & huge_page_mask(h)); + if (huge_zeropage_ok(pte, write, shared)) + zeropage_ok = 1; - if (!pte || huge_pte_none(huge_ptep_get(pte)) || + if (!pte || + (huge_pte_none(huge_ptep_get(pte)) && !zeropage_ok) || (write && !pte_write(huge_ptep_get(pte)))) { int ret; @@ -2113,8 +2126,11 @@ int follow_hugetlb_page(struct mm_struct page = pte_page(huge_ptep_get(pte)); same_page: if (pages) { - get_page(page); - pages[i] = page + pfn_offset; + if (zeropage_ok) + pages[i] = ZERO_PAGE(0); + else + pages[i] = page + pfn_offset; + get_page(pages[i]); } if (vmas) _ Patches currently in -mm which might be from kosaki.motohiro@xxxxxxxxxxxxxx are mm-do_generic_file_read-never-gets-a-null-filp-argument.patch vmscan-use-an-indexed-array-for-lru-variables.patch swap-use-an-array-for-the-lru-pagevecs.patch vmscan-split-lru-lists-into-anon-file-sets.patch vmscan-second-chance-replacement-for-anonymous-pages.patch unevictable-lru-infrastructure.patch unevictable-lru-infrastructure-nommu-fix.patch unevictable-lru-infrastructure-remember-pages-active-state.patch unevictable-lru-infrastructure-defer-vm-event-counting.patch unevictable-infrastructure-lru-add-event-counting-with-statistics.patch unevictable-lru-page-statistics.patch shm_locked-pages-are-unevictable.patch shm_locked-pages-are-unevictable-add-event-counts-to-list-scan.patch mlock-mlocked-pages-are-unevictable.patch mlock-mlocked-pages-are-unevictable-fix.patch doc-unevictable-lru-and-mlocked-pages-documentation-update-2.patch mmap-handle-mlocked-pages-during-map-remap-unmap.patch mmap-handle-mlocked-pages-during-map-remap-unmap-mlock-fix-__mlock_vma_pages_range-comment-block.patch mmap-handle-mlocked-pages-during-map-remap-unmap-mlock-backout-locked_vm-adjustment-during-mmap.patch mmap-handle-mlocked-pages-during-map-remap-unmap-mlock-resubmit-locked_vm-adjustment-as-separate-patch.patch mmap-handle-mlocked-pages-during-map-remap-unmap-mlock-resubmit-locked_vm-adjustment-as-separate-patch-fix.patch mmap-handle-mlocked-pages-during-map-remap-unmap-mlock-fix-return-value-for-munmap-mlock-vma-race.patch mmap-handle-mlocked-pages-during-map-remap-unmap-mlock-update-locked_vm-on-munmap-of-mlocked-region.patch vmstat-mlocked-pages-statistics.patch vmstat-mlocked-pages-statistics-mlocked-pages-add-event-counting-with-statistics.patch swap-cull-unevictable-pages-in-fault-path.patch vmscan-unevictable-lru-scan-sysctl.patch vmscam-kill-unused-lru-functions.patch mlock-revert-mainline-handling-of-mlock-error-return.patch mlock-make-mlock-error-return-posixly-correct.patch mlock-make-mlock-error-return-posixly-correct-fix.patch mm-unlockless-reclaim.patch coredump_filter-add-hugepage-dumping-v4.patch hugepage-support-zero_page.patch mm-more-likely-reclaim-madv_sequential-mappings.patch make-mm-rmapc-anon_vma_cachep-static.patch -- To unsubscribe from this list: send the line "unsubscribe mm-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html