From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-7.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS,URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id E7B6EC10F0B for ; Wed, 3 Apr 2019 19:33:48 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id B07BD2133D for ; Wed, 3 Apr 2019 19:33:48 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727071AbfDCTdq (ORCPT ); Wed, 3 Apr 2019 15:33:46 -0400 Received: from mx1.redhat.com ([209.132.183.28]:51752 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726930AbfDCTdl (ORCPT ); Wed, 3 Apr 2019 15:33:41 -0400 Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.11]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id CC0A499D2E; Wed, 3 Apr 2019 19:33:40 +0000 (UTC) Received: from localhost.localdomain.com (ovpn-125-190.rdu2.redhat.com [10.10.125.190]) by smtp.corp.redhat.com (Postfix) with ESMTP id CC9306012C; Wed, 3 Apr 2019 19:33:39 +0000 (UTC) From: jglisse@redhat.com To: linux-mm@kvack.org, Andrew Morton Cc: linux-kernel@vger.kernel.org, =?UTF-8?q?J=C3=A9r=C3=B4me=20Glisse?= , Dan Williams , John Hubbard , Arnd Bergmann Subject: [PATCH v3 09/12] mm/hmm: allow to mirror vma of a file on a DAX backed filesystem v3 Date: Wed, 3 Apr 2019 15:33:15 -0400 Message-Id: <20190403193318.16478-10-jglisse@redhat.com> In-Reply-To: <20190403193318.16478-1-jglisse@redhat.com> References: <20190403193318.16478-1-jglisse@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-Scanned-By: MIMEDefang 2.79 on 10.5.11.11 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.38]); Wed, 03 Apr 2019 19:33:40 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Jérôme Glisse HMM mirror is a device driver helpers to mirror range of virtual address. It means that the process jobs running on the device can access the same virtual address as the CPU threads of that process. This patch adds support for mirroring mapping of file that are on a DAX block device (ie range of virtual address that is an mmap of a file in a filesystem on a DAX block device). There is no reason to not support such case when mirroring virtual address on a device. Note that unlike GUP code we do not take page reference hence when we back-off we have nothing to undo. Changes since v2: - Added comments about get_dev_pagemap() optimization. Changes since v1: - improved commit message - squashed: Arnd Bergmann: fix unused variable warning in hmm_vma_walk_pud Signed-off-by: Jérôme Glisse Reviewed-by: Ralph Campbell Cc: Andrew Morton Cc: Dan Williams Cc: John Hubbard Cc: Arnd Bergmann --- mm/hmm.c | 138 ++++++++++++++++++++++++++++++++++++++++++++++--------- 1 file changed, 117 insertions(+), 21 deletions(-) diff --git a/mm/hmm.c b/mm/hmm.c index 9140cee24d36..39bc77d7e6e3 100644 --- a/mm/hmm.c +++ b/mm/hmm.c @@ -329,6 +329,7 @@ EXPORT_SYMBOL(hmm_mirror_unregister); struct hmm_vma_walk { struct hmm_range *range; + struct dev_pagemap *pgmap; unsigned long last; bool fault; bool block; @@ -503,6 +504,15 @@ static inline uint64_t pmd_to_hmm_pfn_flags(struct hmm_range *range, pmd_t pmd) range->flags[HMM_PFN_VALID]; } +static inline uint64_t pud_to_hmm_pfn_flags(struct hmm_range *range, pud_t pud) +{ + if (!pud_present(pud)) + return 0; + return pud_write(pud) ? range->flags[HMM_PFN_VALID] | + range->flags[HMM_PFN_WRITE] : + range->flags[HMM_PFN_VALID]; +} + static int hmm_vma_handle_pmd(struct mm_walk *walk, unsigned long addr, unsigned long end, @@ -524,8 +534,19 @@ static int hmm_vma_handle_pmd(struct mm_walk *walk, return hmm_vma_walk_hole_(addr, end, fault, write_fault, walk); pfn = pmd_pfn(pmd) + pte_index(addr); - for (i = 0; addr < end; addr += PAGE_SIZE, i++, pfn++) + for (i = 0; addr < end; addr += PAGE_SIZE, i++, pfn++) { + if (pmd_devmap(pmd)) { + hmm_vma_walk->pgmap = get_dev_pagemap(pfn, + hmm_vma_walk->pgmap); + if (unlikely(!hmm_vma_walk->pgmap)) + return -EBUSY; + } pfns[i] = hmm_pfn_from_pfn(range, pfn) | cpu_flags; + } + if (hmm_vma_walk->pgmap) { + put_dev_pagemap(hmm_vma_walk->pgmap); + hmm_vma_walk->pgmap = NULL; + } hmm_vma_walk->last = end; return 0; } @@ -612,10 +633,24 @@ static int hmm_vma_handle_pte(struct mm_walk *walk, unsigned long addr, if (fault || write_fault) goto fault; + if (pte_devmap(pte)) { + hmm_vma_walk->pgmap = get_dev_pagemap(pte_pfn(pte), + hmm_vma_walk->pgmap); + if (unlikely(!hmm_vma_walk->pgmap)) + return -EBUSY; + } else if (IS_ENABLED(CONFIG_ARCH_HAS_PTE_SPECIAL) && pte_special(pte)) { + *pfn = range->values[HMM_PFN_SPECIAL]; + return -EFAULT; + } + *pfn = hmm_pfn_from_pfn(range, pte_pfn(pte)) | cpu_flags; return 0; fault: + if (hmm_vma_walk->pgmap) { + put_dev_pagemap(hmm_vma_walk->pgmap); + hmm_vma_walk->pgmap = NULL; + } pte_unmap(ptep); /* Fault any virtual address we were asked to fault */ return hmm_vma_walk_hole_(addr, end, fault, write_fault, walk); @@ -703,12 +738,89 @@ static int hmm_vma_walk_pmd(pmd_t *pmdp, return r; } } + if (hmm_vma_walk->pgmap) { + /* + * We do put_dev_pagemap() here and not in hmm_vma_handle_pte() + * so that we can leverage get_dev_pagemap() optimization which + * will not re-take a reference on a pgmap if we already have + * one. + */ + put_dev_pagemap(hmm_vma_walk->pgmap); + hmm_vma_walk->pgmap = NULL; + } pte_unmap(ptep - 1); hmm_vma_walk->last = addr; return 0; } +static int hmm_vma_walk_pud(pud_t *pudp, + unsigned long start, + unsigned long end, + struct mm_walk *walk) +{ + struct hmm_vma_walk *hmm_vma_walk = walk->private; + struct hmm_range *range = hmm_vma_walk->range; + unsigned long addr = start, next; + pmd_t *pmdp; + pud_t pud; + int ret; + +again: + pud = READ_ONCE(*pudp); + if (pud_none(pud)) + return hmm_vma_walk_hole(start, end, walk); + + if (pud_huge(pud) && pud_devmap(pud)) { + unsigned long i, npages, pfn; + uint64_t *pfns, cpu_flags; + bool fault, write_fault; + + if (!pud_present(pud)) + return hmm_vma_walk_hole(start, end, walk); + + i = (addr - range->start) >> PAGE_SHIFT; + npages = (end - addr) >> PAGE_SHIFT; + pfns = &range->pfns[i]; + + cpu_flags = pud_to_hmm_pfn_flags(range, pud); + hmm_range_need_fault(hmm_vma_walk, pfns, npages, + cpu_flags, &fault, &write_fault); + if (fault || write_fault) + return hmm_vma_walk_hole_(addr, end, fault, + write_fault, walk); + + pfn = pud_pfn(pud) + ((addr & ~PUD_MASK) >> PAGE_SHIFT); + for (i = 0; i < npages; ++i, ++pfn) { + hmm_vma_walk->pgmap = get_dev_pagemap(pfn, + hmm_vma_walk->pgmap); + if (unlikely(!hmm_vma_walk->pgmap)) + return -EBUSY; + pfns[i] = hmm_pfn_from_pfn(range, pfn) | cpu_flags; + } + if (hmm_vma_walk->pgmap) { + put_dev_pagemap(hmm_vma_walk->pgmap); + hmm_vma_walk->pgmap = NULL; + } + hmm_vma_walk->last = end; + return 0; + } + + split_huge_pud(walk->vma, pudp, addr); + if (pud_none(*pudp)) + goto again; + + pmdp = pmd_offset(pudp, addr); + do { + next = pmd_addr_end(addr, end); + ret = hmm_vma_walk_pmd(pmdp, addr, next, walk); + if (ret) + return ret; + } while (pmdp++, addr = next, addr != end); + + return 0; +} + static int hmm_vma_walk_hugetlb_entry(pte_t *pte, unsigned long hmask, unsigned long start, unsigned long end, struct mm_walk *walk) @@ -781,14 +893,6 @@ static void hmm_pfns_clear(struct hmm_range *range, *pfns = range->values[HMM_PFN_NONE]; } -static void hmm_pfns_special(struct hmm_range *range) -{ - unsigned long addr = range->start, i = 0; - - for (; addr < range->end; addr += PAGE_SIZE, i++) - range->pfns[i] = range->values[HMM_PFN_SPECIAL]; -} - /* * hmm_range_register() - start tracking change to CPU page table over a range * @range: range @@ -906,12 +1010,6 @@ long hmm_range_snapshot(struct hmm_range *range) if (vma == NULL || (vma->vm_flags & device_vma)) return -EFAULT; - /* FIXME support dax */ - if (vma_is_dax(vma)) { - hmm_pfns_special(range); - return -EINVAL; - } - if (is_vm_hugetlb_page(vma)) { struct hstate *h = hstate_vma(vma); @@ -935,6 +1033,7 @@ long hmm_range_snapshot(struct hmm_range *range) } range->vma = vma; + hmm_vma_walk.pgmap = NULL; hmm_vma_walk.last = start; hmm_vma_walk.fault = false; hmm_vma_walk.range = range; @@ -946,6 +1045,7 @@ long hmm_range_snapshot(struct hmm_range *range) mm_walk.pte_entry = NULL; mm_walk.test_walk = NULL; mm_walk.hugetlb_entry = NULL; + mm_walk.pud_entry = hmm_vma_walk_pud; mm_walk.pmd_entry = hmm_vma_walk_pmd; mm_walk.pte_hole = hmm_vma_walk_hole; mm_walk.hugetlb_entry = hmm_vma_walk_hugetlb_entry; @@ -1011,12 +1111,6 @@ long hmm_range_fault(struct hmm_range *range, bool block) if (vma == NULL || (vma->vm_flags & device_vma)) return -EFAULT; - /* FIXME support dax */ - if (vma_is_dax(vma)) { - hmm_pfns_special(range); - return -EINVAL; - } - if (is_vm_hugetlb_page(vma)) { if (huge_page_shift(hstate_vma(vma)) != range->page_shift && @@ -1039,6 +1133,7 @@ long hmm_range_fault(struct hmm_range *range, bool block) } range->vma = vma; + hmm_vma_walk.pgmap = NULL; hmm_vma_walk.last = start; hmm_vma_walk.fault = true; hmm_vma_walk.block = block; @@ -1051,6 +1146,7 @@ long hmm_range_fault(struct hmm_range *range, bool block) mm_walk.pte_entry = NULL; mm_walk.test_walk = NULL; mm_walk.hugetlb_entry = NULL; + mm_walk.pud_entry = hmm_vma_walk_pud; mm_walk.pmd_entry = hmm_vma_walk_pmd; mm_walk.pte_hole = hmm_vma_walk_hole; mm_walk.hugetlb_entry = hmm_vma_walk_hugetlb_entry; -- 2.17.2