Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752396AbZIGViF (ORCPT ); Mon, 7 Sep 2009 17:38:05 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751917AbZIGViE (ORCPT ); Mon, 7 Sep 2009 17:38:04 -0400 Received: from mk-filter-1-a-1.mail.uk.tiscali.com ([212.74.100.52]:33485 "EHLO mk-filter-1-a-1.mail.uk.tiscali.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751919AbZIGViD (ORCPT ); Mon, 7 Sep 2009 17:38:03 -0400 X-Trace: 259188952/mk-filter-1.mail.uk.tiscali.com/B2C/$b2c-THROTTLED-DYNAMIC/b2c-CUSTOMER-DYNAMIC-IP/79.69.94.54/None/hugh.dickins@tiscali.co.uk X-SBRS: None X-RemoteIP: 79.69.94.54 X-IP-MAIL-FROM: hugh.dickins@tiscali.co.uk X-SMTP-AUTH: X-MUA: X-IP-BHB: Once X-IronPort-Anti-Spam-Filtered: true X-IronPort-Anti-Spam-Result: AugEABcapUpPRV42/2dsb2JhbACBU9c/hBgFgVQ X-IronPort-AV: E=Sophos;i="4.44,348,1249254000"; d="scan'208";a="259188952" Date: Mon, 7 Sep 2009 22:37:14 +0100 (BST) From: Hugh Dickins X-X-Sender: hugh@sister.anvils To: Andrew Morton cc: Mel Gorman , KAMEZAWA Hiroyuki , KOSAKI Motohiro , Linus Torvalds , Nick Piggin , Rik van Riel , linux-kernel@vger.kernel.org, linux-mm@kvack.org Subject: [PATCH 5/8] mm: follow_hugetlb_page flags In-Reply-To: Message-ID: References: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 6166 Lines: 187 follow_hugetlb_page() shouldn't be guessing about the coredump case either: pass the foll_flags down to it, instead of just the write bit. Remove that obscure huge_zeropage_ok() test. The decision is easy, though unlike the non-huge case - here vm_ops->fault is always set. But we know that a fault would serve up zeroes, unless there's already a hugetlbfs pagecache page to back the range. (Alternatively, since hugetlb pages aren't swapped out under pressure, you could save more dump space by arguing that a page not yet faulted into this process cannot be relevant to the dump; but that would be more surprising.) Signed-off-by: Hugh Dickins --- include/linux/hugetlb.h | 4 +- mm/hugetlb.c | 62 ++++++++++++++++++++++---------------- mm/memory.c | 14 ++++---- 3 files changed, 48 insertions(+), 32 deletions(-) --- mm4/include/linux/hugetlb.h 2009-09-05 14:40:16.000000000 +0100 +++ mm5/include/linux/hugetlb.h 2009-09-07 13:16:46.000000000 +0100 @@ -24,7 +24,9 @@ int hugetlb_sysctl_handler(struct ctl_ta int hugetlb_overcommit_handler(struct ctl_table *, int, void __user *, size_t *, loff_t *); int hugetlb_treat_movable_handler(struct ctl_table *, int, void __user *, size_t *, loff_t *); int copy_hugetlb_page_range(struct mm_struct *, struct mm_struct *, struct vm_area_struct *); -int follow_hugetlb_page(struct mm_struct *, struct vm_area_struct *, struct page **, struct vm_area_struct **, unsigned long *, int *, int, int); +int follow_hugetlb_page(struct mm_struct *, struct vm_area_struct *, + struct page **, struct vm_area_struct **, + unsigned long *, int *, int, unsigned int flags); void unmap_hugepage_range(struct vm_area_struct *, unsigned long, unsigned long, struct page *); void __unmap_hugepage_range(struct vm_area_struct *, --- mm4/mm/hugetlb.c 2009-09-05 14:40:16.000000000 +0100 +++ mm5/mm/hugetlb.c 2009-09-07 13:16:46.000000000 +0100 @@ -2016,6 +2016,23 @@ static struct page *hugetlbfs_pagecache_ return find_lock_page(mapping, idx); } +/* Return whether there is a pagecache page to back given address within VMA */ +static bool hugetlbfs_backed(struct hstate *h, + struct vm_area_struct *vma, unsigned long address) +{ + struct address_space *mapping; + pgoff_t idx; + struct page *page; + + mapping = vma->vm_file->f_mapping; + idx = vma_hugecache_offset(h, vma, address); + + page = find_get_page(mapping, idx); + if (page) + put_page(page); + return page != NULL; +} + static int hugetlb_no_page(struct mm_struct *mm, struct vm_area_struct *vma, unsigned long address, pte_t *ptep, unsigned int flags) { @@ -2211,54 +2228,52 @@ 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, - int write) + unsigned int flags) { unsigned long pfn_offset; 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) { pte_t *pte; + int absent; struct page *page; /* * Some archs (sparc64, sh*) have multiple pte_ts to - * each hugepage. We have to make * sure we get the + * each hugepage. We have to make sure we get the * 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; + absent = !pte || huge_pte_none(huge_ptep_get(pte)); + + /* + * When coredumping, it suits get_dump_page if we just return + * an error if there's a hole and no huge pagecache to back it. + */ + if (absent && + ((flags & FOLL_DUMP) && !hugetlbfs_backed(h, vma, vaddr))) { + remainder = 0; + break; + } - if (!pte || - (huge_pte_none(huge_ptep_get(pte)) && !zeropage_ok) || - (write && !pte_write(huge_ptep_get(pte)))) { + if (absent || + ((flags & FOLL_WRITE) && !pte_write(huge_ptep_get(pte)))) { int ret; spin_unlock(&mm->page_table_lock); - ret = hugetlb_fault(mm, vma, vaddr, write); + ret = hugetlb_fault(mm, vma, vaddr, + (flags & FOLL_WRITE) ? FAULT_FLAG_WRITE : 0); spin_lock(&mm->page_table_lock); if (!(ret & VM_FAULT_ERROR)) continue; remainder = 0; - if (!i) - i = -EFAULT; break; } @@ -2266,10 +2281,7 @@ int follow_hugetlb_page(struct mm_struct page = pte_page(huge_ptep_get(pte)); same_page: if (pages) { - if (zeropage_ok) - pages[i] = ZERO_PAGE(0); - else - pages[i] = mem_map_offset(page, pfn_offset); + pages[i] = mem_map_offset(page, pfn_offset); get_page(pages[i]); } @@ -2293,7 +2305,7 @@ same_page: *length = remainder; *position = vaddr; - return i; + return i ? i : -EFAULT; } void hugetlb_change_protection(struct vm_area_struct *vma, --- mm4/mm/memory.c 2009-09-07 13:16:39.000000000 +0100 +++ mm5/mm/memory.c 2009-09-07 13:16:46.000000000 +0100 @@ -1260,17 +1260,19 @@ int __get_user_pages(struct task_struct !(vm_flags & vma->vm_flags)) return i ? : -EFAULT; - if (is_vm_hugetlb_page(vma)) { - i = follow_hugetlb_page(mm, vma, pages, vmas, - &start, &nr_pages, i, write); - continue; - } - foll_flags = FOLL_TOUCH; if (pages) foll_flags |= FOLL_GET; if (flags & GUP_FLAGS_DUMP) foll_flags |= FOLL_DUMP; + if (write) + foll_flags |= FOLL_WRITE; + + if (is_vm_hugetlb_page(vma)) { + i = follow_hugetlb_page(mm, vma, pages, vmas, + &start, &nr_pages, i, foll_flags); + continue; + } do { struct page *page; -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/