The patch titled pagemap: fix pfn calculation for hugepage has been added to the -mm tree. Its filename is pagemap-fix-pfn-calculation-for-hugepage-v3.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/stuff/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: pagemap: fix pfn calculation for hugepage From: Naoya Horiguchi <n-horiguchi@xxxxxxxxxxxxx> When we look into pagemap using page-types with option -p, the value of pfn for hugepages looks wrong (see below.) This is because pte was evaluated only once for one vma although it should be updated for each hugepage. This patch fixes it. $ page-types -p 3277 -Nl -b huge voffset offset len flags 7f21e8a00 11e400 1 ___U___________H_G________________ 7f21e8a01 11e401 1ff ________________TG________________ ^^^ 7f21e8c00 11e400 1 ___U___________H_G________________ 7f21e8c01 11e401 1ff ________________TG________________ ^^^ One hugepage contains 1 head page and 511 tail pages in x86_64 and each two lines represent each hugepage. Voffset and offset mean virtual address and physical address in the page unit, respectively. The different hugepages should not have the same offset value. With this patch applied: $ page-types -p 3386 -Nl -b huge voffset offset len flags 7fec7a600 112c00 1 ___UD__________H_G________________ 7fec7a601 112c01 1ff ________________TG________________ ^^^ 7fec7a800 113200 1 ___UD__________H_G________________ 7fec7a801 113201 1ff ________________TG________________ ^^^ OK More info: - This patch modifies walk_page_range()'s hugepage walker. But the change only affects pagemap_read(), which is the only caller of hugepage callback. - Without this patch, hugetlb_entry() callback is called per vma, that doesn't match the natural expectation from its name. - With this patch, hugetlb_entry() is called per hugepte entry and the callback can become much simpler. Signed-off-by: Naoya Horiguchi <n-horiguchi@xxxxxxxxxxxxx> Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx> Acked-by: Matt Mackall <mpm@xxxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- fs/proc/task_mmu.c | 27 ++++++------------------ include/linux/mm.h | 4 +-- mm/pagewalk.c | 47 +++++++++++++++++++++++++++++++++---------- 3 files changed, 46 insertions(+), 32 deletions(-) diff -puN fs/proc/task_mmu.c~pagemap-fix-pfn-calculation-for-hugepage-v3 fs/proc/task_mmu.c --- a/fs/proc/task_mmu.c~pagemap-fix-pfn-calculation-for-hugepage-v3 +++ a/fs/proc/task_mmu.c @@ -661,31 +661,18 @@ static u64 huge_pte_to_pagemap_entry(pte return pme; } -static int pagemap_hugetlb_range(pte_t *pte, unsigned long addr, - unsigned long end, struct mm_walk *walk) +/* This function walks within one hugetlb entry in the single call */ +static int pagemap_hugetlb_range(pte_t *pte, unsigned long hmask, + unsigned long addr, unsigned long end, + struct mm_walk *walk) { - struct vm_area_struct *vma; struct pagemapread *pm = walk->private; - struct hstate *hs = NULL; int err = 0; + u64 pfn; - vma = find_vma(walk->mm, addr); - if (vma) - hs = hstate_vma(vma); for (; addr != end; addr += PAGE_SIZE) { - u64 pfn = PM_NOT_PRESENT; - - if (vma && (addr >= vma->vm_end)) { - vma = find_vma(walk->mm, addr); - if (vma) - hs = hstate_vma(vma); - } - - if (vma && (vma->vm_start <= addr) && is_vm_hugetlb_page(vma)) { - /* calculate pfn of the "raw" page in the hugepage. */ - int offset = (addr & ~huge_page_mask(hs)) >> PAGE_SHIFT; - pfn = huge_pte_to_pagemap_entry(*pte, offset); - } + int offset = (addr & ~hmask) >> PAGE_SHIFT; + pfn = huge_pte_to_pagemap_entry(*pte, offset); err = add_to_pagemap(addr, pfn, pm); if (err) return err; diff -puN include/linux/mm.h~pagemap-fix-pfn-calculation-for-hugepage-v3 include/linux/mm.h --- a/include/linux/mm.h~pagemap-fix-pfn-calculation-for-hugepage-v3 +++ a/include/linux/mm.h @@ -783,8 +783,8 @@ struct mm_walk { int (*pmd_entry)(pmd_t *, unsigned long, unsigned long, struct mm_walk *); int (*pte_entry)(pte_t *, unsigned long, unsigned long, struct mm_walk *); int (*pte_hole)(unsigned long, unsigned long, struct mm_walk *); - int (*hugetlb_entry)(pte_t *, unsigned long, unsigned long, - struct mm_walk *); + int (*hugetlb_entry)(pte_t *, unsigned long, + unsigned long, unsigned long, struct mm_walk *); struct mm_struct *mm; void *private; }; diff -puN mm/pagewalk.c~pagemap-fix-pfn-calculation-for-hugepage-v3 mm/pagewalk.c --- a/mm/pagewalk.c~pagemap-fix-pfn-calculation-for-hugepage-v3 +++ a/mm/pagewalk.c @@ -80,6 +80,37 @@ static int walk_pud_range(pgd_t *pgd, un return err; } +#ifdef CONFIG_HUGETLB_PAGE +static unsigned long hugetlb_entry_end(struct hstate *h, unsigned long addr, + unsigned long end) +{ + unsigned long boundary = (addr & huge_page_mask(h)) + huge_page_size(h); + return boundary < end ? boundary : end; +} + +static int walk_hugetlb_range(struct vm_area_struct *vma, + unsigned long addr, unsigned long end, + struct mm_walk *walk) +{ + struct hstate *h = hstate_vma(vma); + unsigned long next; + unsigned long hmask = huge_page_mask(h); + pte_t *pte; + int err = 0; + + do { + next = hugetlb_entry_end(h, addr, end); + pte = huge_pte_offset(walk->mm, addr & hmask); + if (pte && walk->hugetlb_entry) + err = walk->hugetlb_entry(pte, hmask, addr, next, walk); + if (err) + return err; + } while (addr = next, addr != end); + + return 0; +} +#endif + /** * walk_page_range - walk a memory map's page tables with a callback * @mm: memory map to walk @@ -128,20 +159,16 @@ int walk_page_range(unsigned long addr, vma = find_vma(walk->mm, addr); #ifdef CONFIG_HUGETLB_PAGE if (vma && is_vm_hugetlb_page(vma)) { - pte_t *pte; - struct hstate *hs; - if (vma->vm_end < next) next = vma->vm_end; - hs = hstate_vma(vma); - pte = huge_pte_offset(walk->mm, - addr & huge_page_mask(hs)); - if (pte && !huge_pte_none(huge_ptep_get(pte)) - && walk->hugetlb_entry) - err = walk->hugetlb_entry(pte, addr, - next, walk); + /* + * Hugepage is very tightly coupled with vma, so + * walk through hugetlb entries within a given vma. + */ + err = walk_hugetlb_range(vma, addr, next, walk); if (err) break; + pgd = pgd_offset(walk->mm, next); continue; } #endif _ Patches currently in -mm which might be from n-horiguchi@xxxxxxxxxxxxx are pagemap-fix-pfn-calculation-for-hugepage-v3.patch mincore-cleanups.patch mincore-break-do_mincore-into-logical-pieces.patch mincore-pass-ranges-as-startend-address-pairs.patch mincore-do-nested-page-table-walks.patch pagemap-add-ifdefs-config_hugetlb_page-on-code-walking-hugetlb-vma.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