From patchwork Wed Jan 17 20:21:02 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Matthew Wilcox (Oracle)" X-Patchwork-Id: 10171531 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id 11833603ED for ; Wed, 17 Jan 2018 20:54:36 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 046D723F88 for ; Wed, 17 Jan 2018 20:54:36 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id EC6CF2434C; Wed, 17 Jan 2018 20:54:35 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.8 required=2.0 tests=BAYES_00,DKIM_SIGNED, RCVD_IN_DNSWL_HI,T_DKIM_INVALID autolearn=unavailable version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 2E88824151 for ; Wed, 17 Jan 2018 20:54:35 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754891AbeAQUyN (ORCPT ); Wed, 17 Jan 2018 15:54:13 -0500 Received: from bombadil.infradead.org ([65.50.211.133]:33881 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753645AbeAQUWl (ORCPT ); Wed, 17 Jan 2018 15:22:41 -0500 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.20170209; h=References:In-Reply-To:Message-Id: Date:Subject:Cc:To:From:Sender:Reply-To:MIME-Version:Content-Type: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Id: List-Help:List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=7vB2B15uU74f4vjqZb/lOPENP1Wr5r1axyfcxs0qMbU=; b=MvQ40AeFib9akrOZ6d3iI6X8v VQ0tWggL3dFI92JHQCNbXDhYSeS/OZesPJN8HaQZSMP0cwDfmvC7qhnLAQaccOjJ0JcU6HxUybRbl xu3eLD2LZsjTI0MEoWTuq03hjWJyRjaZck6M6YjG6XMHiDV6N4jivkdXqAeYDx5unOnbdnGrOmTM8 GO407+DGKZAFeypIbD4abZwaL82TOgnFZoju6bBZWV3adTewFymrvXXEQP2Dqdhrpg0+daQ21TfWH WhKsvE2E4yt5guCdmY2+3gy0G27zbxpDcfIHVVI/w3geT/M+jpDtRbNb9H/5w1CNtx7gujtMA2kCG 1/cAeAH5g==; Received: from willy by bombadil.infradead.org with local (Exim 4.89 #1 (Red Hat Linux)) id 1ebuEJ-0005qa-AH; Wed, 17 Jan 2018 20:22:39 +0000 From: Matthew Wilcox To: linux-kernel@vger.kernel.org Cc: Matthew Wilcox , linux-mm@kvack.org, linux-fsdevel@vger.kernel.org, linux-f2fs-devel@lists.sourceforge.net, linux-nilfs@vger.kernel.org, linux-btrfs@vger.kernel.org, linux-xfs@vger.kernel.org, linux-usb@vger.kernel.org, Bjorn Andersson , Stefano Stabellini , iommu@lists.linux-foundation.org, linux-remoteproc@vger.kernel.org, linux-s390@vger.kernel.org, intel-gfx@lists.freedesktop.org, cgroups@vger.kernel.org, linux-sh@vger.kernel.org, David Howells Subject: [PATCH v6 38/99] mm: Convert collapse_shmem to XArray Date: Wed, 17 Jan 2018 12:21:02 -0800 Message-Id: <20180117202203.19756-39-willy@infradead.org> X-Mailer: git-send-email 2.14.3 In-Reply-To: <20180117202203.19756-1-willy@infradead.org> References: <20180117202203.19756-1-willy@infradead.org> Sender: linux-btrfs-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-btrfs@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP From: Matthew Wilcox I found another victim of the radix tree being hard to use. Because there was no call to radix_tree_preload(), khugepaged was allocating radix_tree_nodes using GFP_ATOMIC. I also converted a local_irq_save()/restore() pair to disable()/enable(). Signed-off-by: Matthew Wilcox --- mm/khugepaged.c | 158 +++++++++++++++++++++++--------------------------------- 1 file changed, 65 insertions(+), 93 deletions(-) diff --git a/mm/khugepaged.c b/mm/khugepaged.c index 55ade70c33bb..9f49d0cd61c2 100644 --- a/mm/khugepaged.c +++ b/mm/khugepaged.c @@ -1282,17 +1282,17 @@ static void retract_page_tables(struct address_space *mapping, pgoff_t pgoff) * * Basic scheme is simple, details are more complex: * - allocate and freeze a new huge page; - * - scan over radix tree replacing old pages the new one + * - scan page cache replacing old pages with the new one * + swap in pages if necessary; * + fill in gaps; - * + keep old pages around in case if rollback is required; - * - if replacing succeed: + * + keep old pages around in case rollback is required; + * - if replacing succeeds: * + copy data over; * + free old pages; * + unfreeze huge page; * - if replacing failed; * + put all pages back and unfreeze them; - * + restore gaps in the radix-tree; + * + restore gaps in the page cache; * + free huge page; */ static void collapse_shmem(struct mm_struct *mm, @@ -1300,12 +1300,11 @@ static void collapse_shmem(struct mm_struct *mm, struct page **hpage, int node) { gfp_t gfp; - struct page *page, *new_page, *tmp; + struct page *new_page; struct mem_cgroup *memcg; pgoff_t index, end = start + HPAGE_PMD_NR; LIST_HEAD(pagelist); - struct radix_tree_iter iter; - void **slot; + XA_STATE(xas, &mapping->pages, start); int nr_none = 0, result = SCAN_SUCCEED; VM_BUG_ON(start & (HPAGE_PMD_NR - 1)); @@ -1330,48 +1329,48 @@ static void collapse_shmem(struct mm_struct *mm, __SetPageLocked(new_page); BUG_ON(!page_ref_freeze(new_page, 1)); - /* - * At this point the new_page is 'frozen' (page_count() is zero), locked - * and not up-to-date. It's safe to insert it into radix tree, because - * nobody would be able to map it or use it in other way until we - * unfreeze it. + * At this point the new_page is 'frozen' (page_count() is zero), + * locked and not up-to-date. It's safe to insert it into the page + * cache, because nobody would be able to map it or use it in other + * way until we unfreeze it. */ - index = start; - xa_lock_irq(&mapping->pages); - radix_tree_for_each_slot(slot, &mapping->pages, &iter, start) { - int n = min(iter.index, end) - index; - - /* - * Handle holes in the radix tree: charge it from shmem and - * insert relevant subpage of new_page into the radix-tree. - */ - if (n && !shmem_charge(mapping->host, n)) { - result = SCAN_FAIL; + /* This will be less messy when we use multi-index entries */ + do { + xas_lock_irq(&xas); + xas_create_range(&xas, end - 1); + if (!xas_error(&xas)) break; - } - nr_none += n; - for (; index < min(iter.index, end); index++) { - radix_tree_insert(&mapping->pages, index, - new_page + (index % HPAGE_PMD_NR)); - } + xas_unlock_irq(&xas); + if (!xas_nomem(&xas, GFP_KERNEL)) + goto out; + } while (1); - /* We are done. */ - if (index >= end) - break; + for (index = start; index < end; index++) { + struct page *page = xas_next(&xas); + + VM_BUG_ON(index != xas.xa_index); + if (!page) { + if (!shmem_charge(mapping->host, 1)) { + result = SCAN_FAIL; + break; + } + xas_store(&xas, new_page + (index % HPAGE_PMD_NR)); + nr_none++; + continue; + } - page = radix_tree_deref_slot_protected(slot, - &mapping->pages.xa_lock); if (xa_is_value(page) || !PageUptodate(page)) { - xa_unlock_irq(&mapping->pages); + xas_unlock_irq(&xas); /* swap in or instantiate fallocated page */ if (shmem_getpage(mapping->host, index, &page, SGP_NOHUGE)) { result = SCAN_FAIL; - goto tree_unlocked; + goto xa_unlocked; } - xa_lock_irq(&mapping->pages); + xas_lock_irq(&xas); + xas_set(&xas, index); } else if (trylock_page(page)) { get_page(page); } else { @@ -1391,7 +1390,7 @@ static void collapse_shmem(struct mm_struct *mm, result = SCAN_TRUNCATED; goto out_unlock; } - xa_unlock_irq(&mapping->pages); + xas_unlock_irq(&xas); if (isolate_lru_page(page)) { result = SCAN_DEL_PAGE_LRU; @@ -1402,17 +1401,16 @@ static void collapse_shmem(struct mm_struct *mm, unmap_mapping_range(mapping, index << PAGE_SHIFT, PAGE_SIZE, 0); - xa_lock_irq(&mapping->pages); + xas_lock(&xas); + xas_set(&xas, index); - slot = radix_tree_lookup_slot(&mapping->pages, index); - VM_BUG_ON_PAGE(page != radix_tree_deref_slot_protected(slot, - &mapping->pages.xa_lock), page); + VM_BUG_ON_PAGE(page != xas_load(&xas), page); VM_BUG_ON_PAGE(page_mapped(page), page); /* * The page is expected to have page_count() == 3: * - we hold a pin on it; - * - one reference from radix tree; + * - one reference from page cache; * - one from isolate_lru_page; */ if (!page_ref_freeze(page, 3)) { @@ -1427,56 +1425,30 @@ static void collapse_shmem(struct mm_struct *mm, list_add_tail(&page->lru, &pagelist); /* Finally, replace with the new page. */ - radix_tree_replace_slot(&mapping->pages, slot, - new_page + (index % HPAGE_PMD_NR)); - - slot = radix_tree_iter_resume(slot, &iter); - index++; + xas_store(&xas, new_page + (index % HPAGE_PMD_NR)); continue; out_lru: - xa_unlock_irq(&mapping->pages); + xas_unlock_irq(&xas); putback_lru_page(page); out_isolate_failed: unlock_page(page); put_page(page); - goto tree_unlocked; + goto xa_unlocked; out_unlock: unlock_page(page); put_page(page); break; } + xas_unlock_irq(&xas); - /* - * Handle hole in radix tree at the end of the range. - * This code only triggers if there's nothing in radix tree - * beyond 'end'. - */ - if (result == SCAN_SUCCEED && index < end) { - int n = end - index; - - if (!shmem_charge(mapping->host, n)) { - result = SCAN_FAIL; - goto tree_locked; - } - - for (; index < end; index++) { - radix_tree_insert(&mapping->pages, index, - new_page + (index % HPAGE_PMD_NR)); - } - nr_none += n; - } - -tree_locked: - xa_unlock_irq(&mapping->pages); -tree_unlocked: - +xa_unlocked: if (result == SCAN_SUCCEED) { - unsigned long flags; + struct page *page, *tmp; struct zone *zone = page_zone(new_page); /* - * Replacing old pages with new one has succeed, now we need to - * copy the content and free old pages. + * Replacing old pages with new one has succeeded, now we + * need to copy the content and free the old pages. */ list_for_each_entry_safe(page, tmp, &pagelist, lru) { copy_highpage(new_page + (page->index % HPAGE_PMD_NR), @@ -1490,16 +1462,16 @@ static void collapse_shmem(struct mm_struct *mm, put_page(page); } - local_irq_save(flags); + local_irq_disable(); __inc_node_page_state(new_page, NR_SHMEM_THPS); if (nr_none) { __mod_node_page_state(zone->zone_pgdat, NR_FILE_PAGES, nr_none); __mod_node_page_state(zone->zone_pgdat, NR_SHMEM, nr_none); } - local_irq_restore(flags); + local_irq_enable(); /* - * Remove pte page tables, so we can re-faulti + * Remove pte page tables, so we can re-fault * the page as huge. */ retract_page_tables(mapping, start); @@ -1514,37 +1486,37 @@ static void collapse_shmem(struct mm_struct *mm, *hpage = NULL; } else { - /* Something went wrong: rollback changes to the radix-tree */ + struct page *page; + /* Something went wrong: roll back page cache changes */ shmem_uncharge(mapping->host, nr_none); - xa_lock_irq(&mapping->pages); - radix_tree_for_each_slot(slot, &mapping->pages, &iter, start) { - if (iter.index >= end) - break; + xas_lock_irq(&xas); + xas_set(&xas, start); + xas_for_each(&xas, page, end - 1) { page = list_first_entry_or_null(&pagelist, struct page, lru); - if (!page || iter.index < page->index) { + if (!page || xas.xa_index < page->index) { if (!nr_none) break; nr_none--; /* Put holes back where they were */ - radix_tree_delete(&mapping->pages, iter.index); + xas_store(&xas, NULL); continue; } - VM_BUG_ON_PAGE(page->index != iter.index, page); + VM_BUG_ON_PAGE(page->index != xas.xa_index, page); /* Unfreeze the page. */ list_del(&page->lru); page_ref_unfreeze(page, 2); - radix_tree_replace_slot(&mapping->pages, slot, page); - slot = radix_tree_iter_resume(slot, &iter); - xa_unlock_irq(&mapping->pages); + xas_store(&xas, page); + xas_pause(&xas); + xas_unlock_irq(&xas); putback_lru_page(page); unlock_page(page); - xa_lock_irq(&mapping->pages); + xas_lock_irq(&xas); } VM_BUG_ON(nr_none); - xa_unlock_irq(&mapping->pages); + xas_unlock_irq(&xas); /* Unfreeze new_page, caller would take care about freeing it */ page_ref_unfreeze(new_page, 1);