From patchwork Tue Sep 15 12:59:35 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Muchun Song X-Patchwork-Id: 11778509 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 6706E139F for ; Wed, 16 Sep 2020 00:43:51 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 48A5820BED for ; Wed, 16 Sep 2020 00:43:51 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=bytedance-com.20150623.gappssmtp.com header.i=@bytedance-com.20150623.gappssmtp.com header.b="kDUWUa2Z" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726757AbgIPAnU (ORCPT ); Tue, 15 Sep 2020 20:43:20 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:48844 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726574AbgIONCG (ORCPT ); Tue, 15 Sep 2020 09:02:06 -0400 Received: from mail-pg1-x541.google.com (mail-pg1-x541.google.com [IPv6:2607:f8b0:4864:20::541]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 92435C061351 for ; Tue, 15 Sep 2020 06:02:05 -0700 (PDT) Received: by mail-pg1-x541.google.com with SMTP id y1so1945419pgk.8 for ; Tue, 15 Sep 2020 06:02:05 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=bytedance-com.20150623.gappssmtp.com; s=20150623; h=from:to:cc:subject:date:message-id:in-reply-to:references :mime-version:content-transfer-encoding; bh=bRCYHUYk1hH5GlJBxp/yuwD+jDdbOfhVtaE95IbYmOc=; b=kDUWUa2ZT8b/MvJ9cAxjIpRzubPelB4YMWzv/FPUiKvVXnR2wgLHRyJPlBTx2dFGPx WdHqq5NcPH25dOl0mZSnquMGz/e7PlX7cC42O/ZFcuDzbaB1biKNjfd1tzk2Oc6YgTFa d9OrrkV9EnSfmyUvBL+Vagbnl6bIxkyZtvYke2r2FbE6JYYwapT5RlbfRUhSJ53rXePP x0HwhaY92MKbHhHjIYRctLxb0cf76tXco75+M5/SFjZJHxPya0IEKclVXhAXblN2hOfT tJTZ6mqsoBnPfVTUIATM/SZDuHHl8VcDFX/HoR/H8KcZZSIb8UOudCvKwJqbipmZCQHD ZKug== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=bRCYHUYk1hH5GlJBxp/yuwD+jDdbOfhVtaE95IbYmOc=; b=DMkpsKJO04105hlZFaaF0T29i8gvoichkHMSY8anQU0ww6RZKQNL4hqQYTGwTtibVL anvU06m2kSLVIO9ZJrOOsPfUNenv7FRrbwXNz3hsmvBfA7PXxU+NeraJYTmSXirupEkS v2/Elm1RMiDyX9mTUjUUngZCUErB1q2/4HSK0XjC+iwPquZl26v8dh/9E8q81rJowzOx nGjvzrfSgj2KATpj+4PGZxJdBkBGDRkv5ZQoHsUJivbl2/tDQMf+3KSpFDLMCJE9N8IT Tqf+1UUjYRmMrOdrka2jxijIRBTh2m9sBP2OcX5dgRUsK4bZnzP1Lr4lxqRxjwWLQpOb zh/g== X-Gm-Message-State: AOAM533tQdpBWp7onAV36NvKFQoVZHuG1+TE9aENNtmHD8rAqCweAZnT 0AtNaBEuX7MFxgC3+1oanVnW4g== X-Google-Smtp-Source: ABdhPJxenPAUPU06D9i1v/P969ZaM4N7XdPUb9tgmOwsHIoNMdA/XIJz1ZOBc23yyjDVGrDlS8zHiA== X-Received: by 2002:a62:178d:0:b029:13e:d13d:a0f8 with SMTP id 135-20020a62178d0000b029013ed13da0f8mr18090356pfx.20.1600174924831; Tue, 15 Sep 2020 06:02:04 -0700 (PDT) Received: from localhost.bytedance.net ([103.136.220.66]) by smtp.gmail.com with ESMTPSA id w185sm14269855pfc.36.2020.09.15.06.01.55 (version=TLS1_2 cipher=ECDHE-ECDSA-AES128-GCM-SHA256 bits=128/128); Tue, 15 Sep 2020 06:02:04 -0700 (PDT) From: Muchun Song To: corbet@lwn.net, mike.kravetz@oracle.com, tglx@linutronix.de, mingo@redhat.com, bp@alien8.de, x86@kernel.org, hpa@zytor.com, dave.hansen@linux.intel.com, luto@kernel.org, peterz@infradead.org, viro@zeniv.linux.org.uk, akpm@linux-foundation.org, paulmck@kernel.org, mchehab+huawei@kernel.org, pawan.kumar.gupta@linux.intel.com, rdunlap@infradead.org, oneukum@suse.com, anshuman.khandual@arm.com, jroedel@suse.de, almasrymina@google.com, rientjes@google.com Cc: linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-fsdevel@vger.kernel.org, Muchun Song Subject: [RFC PATCH 12/24] mm/hugetlb: Defer freeing of hugetlb pages Date: Tue, 15 Sep 2020 20:59:35 +0800 Message-Id: <20200915125947.26204-13-songmuchun@bytedance.com> X-Mailer: git-send-email 2.21.0 (Apple Git-122) In-Reply-To: <20200915125947.26204-1-songmuchun@bytedance.com> References: <20200915125947.26204-1-songmuchun@bytedance.com> MIME-Version: 1.0 Sender: linux-fsdevel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org In the subsequent patch, we will allocate the vmemmap pages when free huge pages. But update_and_free_page() is be called from a non-task context(and hold hugetlb_lock), we can defer the actual freeing in a workqueue to prevent use GFP_ATOMIC to allocate the vmemmap pages. Signed-off-by: Muchun Song --- mm/hugetlb.c | 94 +++++++++++++++++++++++++++++++++++++++++++++++----- 1 file changed, 85 insertions(+), 9 deletions(-) diff --git a/mm/hugetlb.c b/mm/hugetlb.c index a628588a075a..6b57a1183785 100644 --- a/mm/hugetlb.c +++ b/mm/hugetlb.c @@ -1292,6 +1292,8 @@ static inline void destroy_compound_gigantic_page(struct page *page, unsigned int order) { } #endif +static void __free_hugepage(struct hstate *h, struct page *page); + #ifdef CONFIG_HUGETLB_PAGE_FREE_VMEMMAP #include @@ -1642,6 +1644,64 @@ static void free_huge_page_vmemmap(struct hstate *h, struct page *head) free_vmemmap_page_list(&free_pages); } + +/* + * As update_and_free_page() is be called from a non-task context(and hold + * hugetlb_lock), we can defer the actual freeing in a workqueue to prevent + * use GFP_ATOMIC to allocate a lot of vmemmap pages. + * + * update_hpage_vmemmap_workfn() locklessly retrieves the linked list of + * pages to be freed and frees them one-by-one. As the page->mapping pointer + * is going to be cleared in update_hpage_vmemmap_workfn() anyway, it is + * reused as the llist_node structure of a lockless linked list of huge + * pages to be freed. + */ +static LLIST_HEAD(hpage_update_freelist); + +static void update_hpage_vmemmap_workfn(struct work_struct *work) +{ + struct llist_node *node; + struct page *page; + + node = llist_del_all(&hpage_update_freelist); + + while (node) { + page = container_of((struct address_space **)node, + struct page, mapping); + node = node->next; + page->mapping = NULL; + __free_hugepage(page_hstate(page), page); + + cond_resched(); + } +} +static DECLARE_WORK(hpage_update_work, update_hpage_vmemmap_workfn); + +static inline void __update_and_free_page(struct hstate *h, struct page *page) +{ + /* No need to allocate vmemmap pages */ + if (!nr_free_vmemmap(h)) { + __free_hugepage(h, page); + return; + } + + /* + * Defer freeing to avoid using GFP_ATOMIC to allocate vmemmap + * pages. + * + * Only call schedule_work() if hpage_update_freelist is previously + * empty. Otherwise, schedule_work() had been called but the workfn + * hasn't retrieved the list yet. + */ + if (llist_add((struct llist_node *)&page->mapping, + &hpage_update_freelist)) + schedule_work(&hpage_update_work); +} + +static inline void free_gigantic_page_comm(struct hstate *h, struct page *page) +{ + free_gigantic_page(page, huge_page_order(h)); +} #else static inline void hugetlb_vmemmap_init(struct hstate *h) { @@ -1659,17 +1719,39 @@ static inline void vmemmap_pgtable_free(struct hstate *h, struct page *page) static inline void free_huge_page_vmemmap(struct hstate *h, struct page *head) { } + +static inline void __update_and_free_page(struct hstate *h, struct page *page) +{ + __free_hugepage(h, page); +} + +static inline void free_gigantic_page_comm(struct hstate *h, struct page *page) +{ + /* + * Temporarily drop the hugetlb_lock, because + * we might block in free_gigantic_page(). + */ + spin_unlock(&hugetlb_lock); + free_gigantic_page(page, huge_page_order(h)); + spin_lock(&hugetlb_lock); +} #endif static void update_and_free_page(struct hstate *h, struct page *page) { - int i; - if (hstate_is_gigantic(h) && !gigantic_page_runtime_supported()) return; h->nr_huge_pages--; h->nr_huge_pages_node[page_to_nid(page)]--; + + __update_and_free_page(h, page); +} + +static void __free_hugepage(struct hstate *h, struct page *page) +{ + int i; + for (i = 0; i < pages_per_huge_page(h); i++) { page[i].flags &= ~(1 << PG_locked | 1 << PG_error | 1 << PG_referenced | 1 << PG_dirty | @@ -1681,14 +1763,8 @@ static void update_and_free_page(struct hstate *h, struct page *page) set_compound_page_dtor(page, NULL_COMPOUND_DTOR); set_page_refcounted(page); if (hstate_is_gigantic(h)) { - /* - * Temporarily drop the hugetlb_lock, because - * we might block in free_gigantic_page(). - */ - spin_unlock(&hugetlb_lock); destroy_compound_gigantic_page(page, huge_page_order(h)); - free_gigantic_page(page, huge_page_order(h)); - spin_lock(&hugetlb_lock); + free_gigantic_page_comm(h, page); } else { __free_pages(page, huge_page_order(h)); }