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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 39FD1C05052 for ; Thu, 17 Aug 2023 03:31:58 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1347849AbjHQDbX (ORCPT ); Wed, 16 Aug 2023 23:31:23 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:35558 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1347851AbjHQDbL (ORCPT ); Wed, 16 Aug 2023 23:31:11 -0400 Received: from mail.loongson.cn (mail.loongson.cn [114.242.206.163]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id 229272686 for ; Wed, 16 Aug 2023 20:31:05 -0700 (PDT) Received: from loongson.cn (unknown [112.20.109.102]) by gateway (Coremail) with SMTP id _____8Bx5fB4lN1kH1wZAA--.52240S3; Thu, 17 Aug 2023 11:31:04 +0800 (CST) Received: from [192.168.100.8] (unknown [112.20.109.102]) by localhost.localdomain (Coremail) with SMTP id AQAAf8DxJ8x0lN1kmXRcAA--.55498S3; Thu, 17 Aug 2023 11:31:02 +0800 (CST) Message-ID: <61a85639-8716-4df0-80f4-5a58620a049f@loongson.cn> Date: Thu, 17 Aug 2023 11:31:00 +0800 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2 03/13] mm: Convert free_huge_page() to free_huge_folio() Content-Language: en-US To: "Matthew Wilcox (Oracle)" , Andrew Morton Cc: Jens Axboe , io-uring@vger.kernel.org, linux-mm@kvack.org References: <20230816151201.3655946-1-willy@infradead.org> <20230816151201.3655946-4-willy@infradead.org> From: Yanteng Si In-Reply-To: <20230816151201.3655946-4-willy@infradead.org> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-CM-TRANSID: AQAAf8DxJ8x0lN1kmXRcAA--.55498S3 X-CM-SenderInfo: pvl1t0pwhqwqxorr0wxvrqhubq/ X-Coremail-Antispam: 1Uk129KBj9fXoW3CF1rGF1xJrW7ZFWxWr1Utwc_yoW8GF1xto WftwsFva1fGF13tr48GryDtF1UWayYk3yrJa13Cr1kAF17Zrn0vw47tF98Jr97uFW5WF1x CFW8J34fKF97JFn3l-sFpf9Il3svdjkaLaAFLSUrUUUU1b8apTn2vfkv8UJUUUU8wcxFpf 9Il3svdxBIdaVrn0xqx4xG64xvF2IEw4CE5I8CrVC2j2Jv73VFW2AGmfu7bjvjm3AaLaJ3 UjIYCTnIWjp_UUUY67kC6x804xWl14x267AKxVWUJVW8JwAFc2x0x2IEx4CE42xK8VAvwI 8IcIk0rVWrJVCq3wAFIxvE14AKwVWUXVWUAwA2ocxC64kIII0Yj41l84x0c7CEw4AK67xG Y2AK021l84ACjcxK6xIIjxv20xvE14v26r4j6ryUM28EF7xvwVC0I7IYx2IY6xkF7I0E14 v26r4j6F4UM28EF7xvwVC2z280aVAFwI0_Gr1j6F4UJwA2z4x0Y4vEx4A2jsIEc7CjxVAF wI0_Gr1j6F4UJwAaw2AFwI0_Jrv_JF1le2I262IYc4CY6c8Ij28IcVAaY2xG8wAqjxCEc2 xF0cIa020Ex4CE44I27wAqx4xG64xvF2IEw4CE5I8CrVC2j2WlYx0E2Ix0cI8IcVAFwI0_ Jrv_JF1lYx0Ex4A2jsIE14v26r1j6r4UMcvjeVCFs4IE7xkEbVWUJVW8JwACjcxG0xvEwI xGrwCF04k20xvY0x0EwIxGrwCFx2IqxVCFs4IE7xkEbVWUJVW8JwCFI7km07C267AKxVWU XVWUAwC20s026c02F40E14v26r1j6r18MI8I3I0E7480Y4vE14v26r106r1rMI8E67AF67 kF1VAFwI0_JF0_Jw1lIxkGc2Ij64vIr41lIxAIcVC0I7IYx2IY67AKxVWUJVWUCwCI42IY 6xIIjxv20xvEc7CjxVAFwI0_Jr0_Gr1lIxAIcVCF04k26cxKx2IYs7xG6r1j6r1xMIIF0x vEx4A2jsIE14v26r1j6r4UMIIF0xvEx4A2jsIEc7CjxVAFwI0_Jr0_GrUvcSsGvfC2Kfnx nUUI43ZEXa7IU8hiSPUUUUU== Precedence: bulk List-ID: X-Mailing-List: io-uring@vger.kernel.org 在 2023/8/16 23:11, Matthew Wilcox (Oracle) 写道: > Pass a folio instead of the head page to save a few instructions. > Update the documentation, at least in English. > > Signed-off-by: Matthew Wilcox (Oracle) > Cc: Yanteng Si > --- > Documentation/mm/hugetlbfs_reserv.rst | 14 +++--- > .../zh_CN/mm/hugetlbfs_reserv.rst | 4 +- > include/linux/hugetlb.h | 2 +- > mm/hugetlb.c | 48 +++++++++---------- > mm/page_alloc.c | 2 +- > 5 files changed, 34 insertions(+), 36 deletions(-) > > diff --git a/Documentation/mm/hugetlbfs_reserv.rst b/Documentation/mm/hugetlbfs_reserv.rst > index d9c2b0f01dcd..4914fbf07966 100644 > --- a/Documentation/mm/hugetlbfs_reserv.rst > +++ b/Documentation/mm/hugetlbfs_reserv.rst > @@ -271,12 +271,12 @@ to the global reservation count (resv_huge_pages). > Freeing Huge Pages > ================== > > -Huge page freeing is performed by the routine free_huge_page(). This routine > -is the destructor for hugetlbfs compound pages. As a result, it is only > -passed a pointer to the page struct. When a huge page is freed, reservation > -accounting may need to be performed. This would be the case if the page was > -associated with a subpool that contained reserves, or the page is being freed > -on an error path where a global reserve count must be restored. > +Huge pages are freed by free_huge_folio(). It is only passed a pointer > +to the folio as it is called from the generic MM code. When a huge page > +is freed, reservation accounting may need to be performed. This would > +be the case if the page was associated with a subpool that contained > +reserves, or the page is being freed on an error path where a global > +reserve count must be restored. > > The page->private field points to any subpool associated with the page. > If the PagePrivate flag is set, it indicates the global reserve count should > @@ -525,7 +525,7 @@ However, there are several instances where errors are encountered after a huge > page is allocated but before it is instantiated. In this case, the page > allocation has consumed the reservation and made the appropriate subpool, > reservation map and global count adjustments. If the page is freed at this > -time (before instantiation and clearing of PagePrivate), then free_huge_page > +time (before instantiation and clearing of PagePrivate), then free_huge_folio > will increment the global reservation count. However, the reservation map > indicates the reservation was consumed. This resulting inconsistent state > will cause the 'leak' of a reserved huge page. The global reserve count will > diff --git a/Documentation/translations/zh_CN/mm/hugetlbfs_reserv.rst b/Documentation/translations/zh_CN/mm/hugetlbfs_reserv.rst > index b7a0544224ad..0f7e7fb5ca8c 100644 > --- a/Documentation/translations/zh_CN/mm/hugetlbfs_reserv.rst > +++ b/Documentation/translations/zh_CN/mm/hugetlbfs_reserv.rst > @@ -219,7 +219,7 @@ vma_commit_reservation()之间，预留映射有可能被改变。如果hugetlb_ > 释放巨页 > ======== > > -巨页释放是由函数free_huge_page()执行的。这个函数是hugetlbfs复合页的析构器。因此，它只传 > +巨页释放是由函数free_huge_folio()执行的。这个函数是hugetlbfs复合页的析构器。因此，它只传 > 递一个指向页面结构体的指针。当一个巨页被释放时，可能需要进行预留计算。如果该页与包含保 > 留的子池相关联，或者该页在错误路径上被释放，必须恢复全局预留计数，就会出现这种情况。 @@ -219,9 +219,10 @@ vma_commit_reservation()之间，预留映射有可能被改变。如果hugetlb_  释放巨页  ======== -巨页释放是由函数free_huge_page()执行的。这个函数是hugetlbfs复合页的析构器。因此，它只传 -递一个指向页面结构体的指针。当一个巨页被释放时，可能需要进行预留计算。如果该页与包含保 -留的子池相关联，或者该页在错误路径上被释放，必须恢复全局预留计数，就会出现这种情况。 +巨页由free_huge_folio()释放。从公共MM代码中调用free_huge_folio()时，只会传递一个folio +（物理连续、虚拟连续的2^n次的PAGE_SIZE的一些bytes的集合，当然这个n也是允许是0的）指针。 +当一个巨页被释放时，可能需要进行预留计算。如果该页与包含保留的子池相关联，或者该页在错 +误路径上被释放，必须恢复全局预留计数，就会出现这种情况。  page->private字段指向与该页相关的任何子池。如果PagePrivate标志被设置，它表明全局预留计数  应该被调整（关于如何设置这些标志的信息，请参见 Thanks, Yanteng > > @@ -387,7 +387,7 @@ region_count()在解除私有巨页映射时被调用。在私有映射中，预 > > 然而，有几种情况是，在一个巨页被分配后，但在它被实例化之前，就遇到了错误。在这种情况下， > 页面分配已经消耗了预留，并进行了适当的子池、预留映射和全局计数调整。如果页面在这个时候被释放 > -（在实例化和清除PagePrivate之前），那么free_huge_page将增加全局预留计数。然而，预留映射 > +（在实例化和清除PagePrivate之前），那么free_huge_folio将增加全局预留计数。然而，预留映射 > 显示报留被消耗了。这种不一致的状态将导致预留的巨页的 “泄漏” 。全局预留计数将比它原本的要高， > 并阻止分配一个预先分配的页面。 > > diff --git a/include/linux/hugetlb.h b/include/linux/hugetlb.h > index 5a1dfaffbd80..5b2626063f4f 100644 > --- a/include/linux/hugetlb.h > +++ b/include/linux/hugetlb.h > @@ -26,7 +26,7 @@ typedef struct { unsigned long pd; } hugepd_t; > #define __hugepd(x) ((hugepd_t) { (x) }) > #endif > > -void free_huge_page(struct page *page); > +void free_huge_folio(struct folio *folio); > > #ifdef CONFIG_HUGETLB_PAGE > > diff --git a/mm/hugetlb.c b/mm/hugetlb.c > index e327a5a7602c..086eb51bf845 100644 > --- a/mm/hugetlb.c > +++ b/mm/hugetlb.c > @@ -1706,10 +1706,10 @@ static void add_hugetlb_folio(struct hstate *h, struct folio *folio, > zeroed = folio_put_testzero(folio); > if (unlikely(!zeroed)) > /* > - * It is VERY unlikely soneone else has taken a ref on > - * the page. In this case, we simply return as the > - * hugetlb destructor (free_huge_page) will be called > - * when this other ref is dropped. > + * It is VERY unlikely soneone else has taken a ref > + * on the folio. In this case, we simply return as > + * free_huge_folio() will be called when this other ref > + * is dropped. > */ > return; > > @@ -1875,13 +1875,12 @@ struct hstate *size_to_hstate(unsigned long size) > return NULL; > } > > -void free_huge_page(struct page *page) > +void free_huge_folio(struct folio *folio) > { > /* > * Can't pass hstate in here because it is called from the > * compound page destructor. > */ > - struct folio *folio = page_folio(page); > struct hstate *h = folio_hstate(folio); > int nid = folio_nid(folio); > struct hugepage_subpool *spool = hugetlb_folio_subpool(folio); > @@ -1936,7 +1935,7 @@ void free_huge_page(struct page *page) > spin_unlock_irqrestore(&hugetlb_lock, flags); > update_and_free_hugetlb_folio(h, folio, true); > } else { > - arch_clear_hugepage_flags(page); > + arch_clear_hugepage_flags(&folio->page); > enqueue_hugetlb_folio(h, folio); > spin_unlock_irqrestore(&hugetlb_lock, flags); > } > @@ -2246,7 +2245,7 @@ static int alloc_pool_huge_page(struct hstate *h, nodemask_t *nodes_allowed, > folio = alloc_fresh_hugetlb_folio(h, gfp_mask, node, > nodes_allowed, node_alloc_noretry); > if (folio) { > - free_huge_page(&folio->page); /* free it into the hugepage allocator */ > + free_huge_folio(folio); /* free it into the hugepage allocator */ > return 1; > } > } > @@ -2429,13 +2428,13 @@ static struct folio *alloc_surplus_hugetlb_folio(struct hstate *h, > * We could have raced with the pool size change. > * Double check that and simply deallocate the new page > * if we would end up overcommiting the surpluses. Abuse > - * temporary page to workaround the nasty free_huge_page > + * temporary page to workaround the nasty free_huge_folio > * codeflow > */ > if (h->surplus_huge_pages >= h->nr_overcommit_huge_pages) { > folio_set_hugetlb_temporary(folio); > spin_unlock_irq(&hugetlb_lock); > - free_huge_page(&folio->page); > + free_huge_folio(folio); > return NULL; > } > > @@ -2547,8 +2546,7 @@ static int gather_surplus_pages(struct hstate *h, long delta) > __must_hold(&hugetlb_lock) > { > LIST_HEAD(surplus_list); > - struct folio *folio; > - struct page *page, *tmp; > + struct folio *folio, *tmp; > int ret; > long i; > long needed, allocated; > @@ -2608,21 +2606,21 @@ static int gather_surplus_pages(struct hstate *h, long delta) > ret = 0; > > /* Free the needed pages to the hugetlb pool */ > - list_for_each_entry_safe(page, tmp, &surplus_list, lru) { > + list_for_each_entry_safe(folio, tmp, &surplus_list, lru) { > if ((--needed) < 0) > break; > /* Add the page to the hugetlb allocator */ > - enqueue_hugetlb_folio(h, page_folio(page)); > + enqueue_hugetlb_folio(h, folio); > } > free: > spin_unlock_irq(&hugetlb_lock); > > /* > * Free unnecessary surplus pages to the buddy allocator. > - * Pages have no ref count, call free_huge_page directly. > + * Pages have no ref count, call free_huge_folio directly. > */ > - list_for_each_entry_safe(page, tmp, &surplus_list, lru) > - free_huge_page(page); > + list_for_each_entry_safe(folio, tmp, &surplus_list, lru) > + free_huge_folio(folio); > spin_lock_irq(&hugetlb_lock); > > return ret; > @@ -2836,11 +2834,11 @@ static long vma_del_reservation(struct hstate *h, > * 2) No reservation was in place for the page, so hugetlb_restore_reserve is > * not set. However, alloc_hugetlb_folio always updates the reserve map. > * > - * In case 1, free_huge_page later in the error path will increment the > - * global reserve count. But, free_huge_page does not have enough context > + * In case 1, free_huge_folio later in the error path will increment the > + * global reserve count. But, free_huge_folio does not have enough context > * to adjust the reservation map. This case deals primarily with private > * mappings. Adjust the reserve map here to be consistent with global > - * reserve count adjustments to be made by free_huge_page. Make sure the > + * reserve count adjustments to be made by free_huge_folio. Make sure the > * reserve map indicates there is a reservation present. > * > * In case 2, simply undo reserve map modifications done by alloc_hugetlb_folio. > @@ -2856,7 +2854,7 @@ void restore_reserve_on_error(struct hstate *h, struct vm_area_struct *vma, > * Rare out of memory condition in reserve map > * manipulation. Clear hugetlb_restore_reserve so > * that global reserve count will not be incremented > - * by free_huge_page. This will make it appear > + * by free_huge_folio. This will make it appear > * as though the reservation for this folio was > * consumed. This may prevent the task from > * faulting in the folio at a later time. This > @@ -3232,7 +3230,7 @@ static void __init gather_bootmem_prealloc(void) > if (prep_compound_gigantic_folio(folio, huge_page_order(h))) { > WARN_ON(folio_test_reserved(folio)); > prep_new_hugetlb_folio(h, folio, folio_nid(folio)); > - free_huge_page(page); /* add to the hugepage allocator */ > + free_huge_folio(folio); /* add to the hugepage allocator */ > } else { > /* VERY unlikely inflated ref count on a tail page */ > free_gigantic_folio(folio, huge_page_order(h)); > @@ -3264,7 +3262,7 @@ static void __init hugetlb_hstate_alloc_pages_onenode(struct hstate *h, int nid) > &node_states[N_MEMORY], NULL); > if (!folio) > break; > - free_huge_page(&folio->page); /* free it into the hugepage allocator */ > + free_huge_folio(folio); /* free it into the hugepage allocator */ > } > cond_resched(); > } > @@ -3542,7 +3540,7 @@ static int set_max_huge_pages(struct hstate *h, unsigned long count, int nid, > while (count > persistent_huge_pages(h)) { > /* > * If this allocation races such that we no longer need the > - * page, free_huge_page will handle it by freeing the page > + * page, free_huge_folio will handle it by freeing the page > * and reducing the surplus. > */ > spin_unlock_irq(&hugetlb_lock); > @@ -3658,7 +3656,7 @@ static int demote_free_hugetlb_folio(struct hstate *h, struct folio *folio) > prep_compound_page(subpage, target_hstate->order); > folio_change_private(inner_folio, NULL); > prep_new_hugetlb_folio(target_hstate, inner_folio, nid); > - free_huge_page(subpage); > + free_huge_folio(inner_folio); > } > mutex_unlock(&target_hstate->resize_lock); > > diff --git a/mm/page_alloc.c b/mm/page_alloc.c > index 548c8016190b..b569fd5562aa 100644 > --- a/mm/page_alloc.c > +++ b/mm/page_alloc.c > @@ -620,7 +620,7 @@ void destroy_large_folio(struct folio *folio) > enum compound_dtor_id dtor = folio->_folio_dtor; > > if (folio_test_hugetlb(folio)) { > - free_huge_page(&folio->page); > + free_huge_folio(folio); > return; > } >