Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756632AbbEUUYZ (ORCPT ); Thu, 21 May 2015 16:24:25 -0400 Received: from mx1.redhat.com ([209.132.183.28]:51397 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756580AbbEUUYV (ORCPT ); Thu, 21 May 2015 16:24:21 -0400 From: jglisse@redhat.com To: akpm@linux-foundation.org Cc: , linux-mm@kvack.org, Linus Torvalds , , Mel Gorman , "H. Peter Anvin" , Peter Zijlstra , Andrea Arcangeli , Johannes Weiner , Larry Woodman , Rik van Riel , Dave Airlie , Brendan Conoboy , Joe Donohue , Duncan Poole , Sherry Cheung , Subhash Gutti , John Hubbard , Mark Hairgrove , Lucien Dunning , Cameron Buschardt , Arvind Gopalakrishnan , Haggai Eran , Shachar Raindel , Liran Liss , Roland Dreier , Ben Sander , Greg Stoner , John Bridgman , Michael Mantor , Paul Blinzer , Laurent Morichetti , Alexander Deucher , Oded Gabbay , =?UTF-8?q?J=C3=A9r=C3=B4me=20Glisse?= , Jatin Kumar Subject: [PATCH 25/36] HMM: add helpers for migration back to system memory. Date: Thu, 21 May 2015 16:23:01 -0400 Message-Id: <1432239792-5002-6-git-send-email-jglisse@redhat.com> In-Reply-To: <1432239792-5002-1-git-send-email-jglisse@redhat.com> References: <1432236705-4209-1-git-send-email-j.glisse@gmail.com> <1432239792-5002-1-git-send-email-jglisse@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 6127 Lines: 214 From: Jérôme Glisse This patch add all necessary functions and helpers for migration from device memory back to system memory. They are 3 differents case that would use that code : - CPU page fault - fork - device driver request Note that this patch use regular memory accounting this means that migration can fail as a result of memory cgroup resource exhaustion. Latter patches will modify memcg to allow to keep remote memory accounted as regular memory thus removing this point of failure. Signed-off-by: Jérôme Glisse Signed-off-by: Sherry Cheung Signed-off-by: Subhash Gutti Signed-off-by: Mark Hairgrove Signed-off-by: John Hubbard Signed-off-by: Jatin Kumar --- mm/hmm.c | 157 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 157 insertions(+) diff --git a/mm/hmm.c b/mm/hmm.c index b8807b2..1208f64 100644 --- a/mm/hmm.c +++ b/mm/hmm.c @@ -50,6 +50,12 @@ static struct mmu_notifier_ops hmm_notifier_ops; static inline struct hmm_mirror *hmm_mirror_ref(struct hmm_mirror *mirror); static inline void hmm_mirror_unref(struct hmm_mirror **mirror); static void hmm_mirror_kill(struct hmm_mirror *mirror); +static int hmm_mirror_migrate_back(struct hmm_mirror *mirror, + struct hmm_event *event, + pte_t *new_pte, + dma_addr_t *dst, + unsigned long start, + unsigned long end); static inline int hmm_mirror_update(struct hmm_mirror *mirror, struct hmm_event *event, struct page *page); @@ -425,6 +431,46 @@ static struct mmu_notifier_ops hmm_notifier_ops = { }; +static int hmm_migrate_back(struct hmm *hmm, + struct hmm_event *event, + struct mm_struct *mm, + struct vm_area_struct *vma, + pte_t *new_pte, + dma_addr_t *dst, + unsigned long start, + unsigned long end) +{ + struct hmm_mirror *mirror; + int r, ret; + + /* + * Do not return right away on error, as there might be valid page we + * can migrate. + */ + ret = mm_hmm_migrate_back(mm, vma, new_pte, start, end); + +again: + down_read(&hmm->rwsem); + hlist_for_each_entry(mirror, &hmm->mirrors, mlist) { + r = hmm_mirror_migrate_back(mirror, event, new_pte, + dst, start, end); + if (r) { + ret = ret ? ret : r; + mirror = hmm_mirror_ref(mirror); + BUG_ON(!mirror); + up_read(&hmm->rwsem); + hmm_mirror_kill(mirror); + hmm_mirror_unref(&mirror); + goto again; + } + } + up_read(&hmm->rwsem); + + mm_hmm_migrate_back_cleanup(mm, vma, new_pte, dst, start, end); + + return ret; +} + int hmm_handle_cpu_fault(struct mm_struct *mm, struct vm_area_struct *vma, pmd_t *pmdp, unsigned long addr, @@ -1085,6 +1131,117 @@ out: } EXPORT_SYMBOL(hmm_mirror_fault); +static int hmm_mirror_migrate_back(struct hmm_mirror *mirror, + struct hmm_event *event, + pte_t *new_pte, + dma_addr_t *dst, + unsigned long start, + unsigned long end) +{ + unsigned long addr, i, npages = (end - start) >> PAGE_SHIFT; + struct hmm_device *device = mirror->device; + struct device *dev = mirror->device->dev; + struct hmm_pt_iter iter; + int r, ret = 0; + + hmm_pt_iter_init(&iter); + for (addr = start, i = 0; addr < end; addr += PAGE_SIZE, ++i) { + dma_addr_t *hmm_pte; + + hmm_pte_clear_select(&dst[i]); + + if (!pte_present(new_pte[i])) + continue; + hmm_pte = hmm_pt_iter_update(&iter, &mirror->pt, addr); + if (!hmm_pte) + continue; + + if (!hmm_pte_test_valid_dev(hmm_pte)) + continue; + + dst[i] = hmm_pte_from_pfn(pte_pfn(new_pte[i])); + hmm_pte_set_select(&dst[i]); + hmm_pte_set_write(&dst[i]); + } + + if (device->dev) { + ret = hmm_mirror_dma_map_range(mirror, dst, NULL, npages); + if (ret) { + for (i = 0; i < npages; ++i) { + if (!hmm_pte_test_select(&dst[i])) + continue; + if (hmm_pte_test_valid_dma(&dst[i])) + continue; + dst[i] = 0; + } + } + } + + r = device->ops->copy_from_device(mirror, event, dst, start, end); + + /* Update mirror page table with successfully migrated entry. */ + for (addr = start; addr < end;) { + unsigned long idx, next, npages; + dma_addr_t *hmm_pte; + + hmm_pte = hmm_pt_iter_update(&iter, &mirror->pt, addr); + if (!hmm_pte) { + addr = hmm_pt_iter_next(&iter, &mirror->pt, + addr, end); + continue; + } + + next = hmm_pt_level_next(&mirror->pt, addr, end, + mirror->pt.llevel - 1); + + idx = (addr - event->start) >> PAGE_SHIFT; + npages = (next - addr) >> PAGE_SHIFT; + hmm_pt_iter_directory_lock(&iter, &mirror->pt); + for (i = 0; i < npages; i++, idx++) { + if (!hmm_pte_test_valid_pfn(&dst[idx]) && + !hmm_pte_test_valid_dma(&dst[idx])) { + if (hmm_pte_test_valid_dev(&hmm_pte[i])) { + hmm_pte[i] = 0; + hmm_pt_iter_directory_unref(&iter, + mirror->pt.llevel); + } + continue; + } + + VM_BUG_ON(!hmm_pte_test_select(&dst[idx])); + VM_BUG_ON(!hmm_pte_test_valid_dev(&hmm_pte[i])); + hmm_pte[i] = dst[idx]; + } + hmm_pt_iter_directory_unlock(&iter, &mirror->pt); + + /* DMA unmap failed migrate entry. */ + if (dev) { + idx = (addr - event->start) >> PAGE_SHIFT; + for (i = 0; i < npages; i++, idx++) { + dma_addr_t dma_addr; + + /* + * Failed entry have the valid bit clear but + * the select bit remain intact. + */ + if (!hmm_pte_test_select(&dst[idx]) && + !hmm_pte_test_valid_dma(&dst[i])) + continue; + + hmm_pte_set_valid_dma(&dst[idx]); + dma_addr = hmm_pte_dma_addr(*hmm_pte); + dma_unmap_page(dev, dma_addr, PAGE_SIZE, + DMA_BIDIRECTIONAL); + } + } + + addr = next; + } + hmm_pt_iter_fini(&iter, &mirror->pt); + + return ret ? ret : r; +} + /* hmm_mirror_range_discard() - discard a range of address. * * @mirror: The mirror struct. -- 1.9.3 -- 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/