From patchwork Wed Mar 29 14:13:12 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: David Howells X-Patchwork-Id: 13192564 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 4A0F2C77B6C for ; Wed, 29 Mar 2023 14:16:44 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230429AbjC2OQm (ORCPT ); Wed, 29 Mar 2023 10:16:42 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:53234 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230241AbjC2OQd (ORCPT ); Wed, 29 Mar 2023 10:16:33 -0400 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 01FF659D8 for ; Wed, 29 Mar 2023 07:15:10 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1680099262; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=w9vYmidIh5WhninpbPh1DpHK4Q4l9z+4/ehUwmRVCvg=; b=ihZieKEPis50jocnwXZWG6sWbc06fopyazPraZXycY7igVKA19CwgVCo44ipQq0W6KZoyC Je0TSsaSPksv+wfDgOqYYsIc7jJ4YfyFJjOJ22Oh4Xpew3lk7OVBVNO49lORHO2zomCd8d 1p1DlVcQLKqjERa5Ve+hyoTFENtp7+o= Received: from mimecast-mx02.redhat.com (mimecast-mx02.redhat.com [66.187.233.88]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-187-vEQ2qQN_Nv6Frz5PzfcuyA-1; Wed, 29 Mar 2023 10:14:16 -0400 X-MC-Unique: vEQ2qQN_Nv6Frz5PzfcuyA-1 Received: from smtp.corp.redhat.com (int-mx02.intmail.prod.int.rdu2.redhat.com [10.11.54.2]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id C7D96801779; Wed, 29 Mar 2023 14:14:15 +0000 (UTC) Received: from warthog.procyon.org.uk (unknown [10.33.36.18]) by smtp.corp.redhat.com (Postfix) with ESMTP id E3D6E4020C83; Wed, 29 Mar 2023 14:14:13 +0000 (UTC) From: David Howells To: Matthew Wilcox , "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni Cc: David Howells , Al Viro , Christoph Hellwig , Jens Axboe , Jeff Layton , Christian Brauner , Chuck Lever III , Linus Torvalds , netdev@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org Subject: [RFC PATCH v2 06/48] mm: Make the page_frag_cache allocator use multipage folios Date: Wed, 29 Mar 2023 15:13:12 +0100 Message-Id: <20230329141354.516864-7-dhowells@redhat.com> In-Reply-To: <20230329141354.516864-1-dhowells@redhat.com> References: <20230329141354.516864-1-dhowells@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 3.1 on 10.11.54.2 Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org X-Patchwork-State: RFC Change the page_frag_cache allocator to use multipage folios rather than groups of pages. This reduces page_frag_free to just a folio_put() or put_page(). Signed-off-by: David Howells cc: "David S. Miller" cc: Eric Dumazet cc: Jakub Kicinski cc: Paolo Abeni cc: Jens Axboe cc: Matthew Wilcox cc: netdev@vger.kernel.org --- include/linux/mm_types.h | 13 ++---- mm/page_frag_alloc.c | 88 +++++++++++++++++++--------------------- 2 files changed, 45 insertions(+), 56 deletions(-) diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h index 0722859c3647..49a70b3f44a9 100644 --- a/include/linux/mm_types.h +++ b/include/linux/mm_types.h @@ -420,18 +420,13 @@ static inline void *folio_get_private(struct folio *folio) } struct page_frag_cache { - void * va; -#if (PAGE_SIZE < PAGE_FRAG_CACHE_MAX_SIZE) - __u16 offset; - __u16 size; -#else - __u32 offset; -#endif + struct folio *folio; + unsigned int offset; /* we maintain a pagecount bias, so that we dont dirty cache line * containing page->_refcount every time we allocate a fragment. */ - unsigned int pagecnt_bias; - bool pfmemalloc; + unsigned int pagecnt_bias; + bool pfmemalloc; }; typedef unsigned long vm_flags_t; diff --git a/mm/page_frag_alloc.c b/mm/page_frag_alloc.c index bee95824ef8f..c3792b68ce32 100644 --- a/mm/page_frag_alloc.c +++ b/mm/page_frag_alloc.c @@ -16,33 +16,34 @@ #include #include -static struct page *__page_frag_cache_refill(struct page_frag_cache *nc, - gfp_t gfp_mask) +/* + * Allocate a new folio for the frag cache. + */ +static struct folio *page_frag_cache_refill(struct page_frag_cache *nc, + gfp_t gfp_mask) { - struct page *page = NULL; + struct folio *folio = NULL; gfp_t gfp = gfp_mask; #if (PAGE_SIZE < PAGE_FRAG_CACHE_MAX_SIZE) - gfp_mask |= __GFP_COMP | __GFP_NOWARN | __GFP_NORETRY | - __GFP_NOMEMALLOC; - page = alloc_pages_node(NUMA_NO_NODE, gfp_mask, - PAGE_FRAG_CACHE_MAX_ORDER); - nc->size = page ? PAGE_FRAG_CACHE_MAX_SIZE : PAGE_SIZE; + gfp_mask |= __GFP_NOWARN | __GFP_NORETRY | __GFP_NOMEMALLOC; + folio = folio_alloc(gfp_mask, PAGE_FRAG_CACHE_MAX_ORDER); #endif - if (unlikely(!page)) - page = alloc_pages_node(NUMA_NO_NODE, gfp, 0); - - nc->va = page ? page_address(page) : NULL; + if (unlikely(!folio)) + folio = folio_alloc(gfp, 0); - return page; + if (folio) + nc->folio = folio; + return folio; } void __page_frag_cache_drain(struct page *page, unsigned int count) { - VM_BUG_ON_PAGE(page_ref_count(page) == 0, page); + struct folio *folio = page_folio(page); - if (page_ref_sub_and_test(page, count - 1)) - __free_pages(page, compound_order(page)); + VM_BUG_ON_FOLIO(folio_ref_count(folio) == 0, folio); + + folio_put_refs(folio, count); } EXPORT_SYMBOL(__page_frag_cache_drain); @@ -50,54 +51,47 @@ void *page_frag_alloc_align(struct page_frag_cache *nc, unsigned int fragsz, gfp_t gfp_mask, unsigned int align_mask) { - unsigned int size = PAGE_SIZE; - struct page *page; - int offset; + struct folio *folio = nc->folio; + size_t offset; - if (unlikely(!nc->va)) { + if (unlikely(!folio)) { refill: - page = __page_frag_cache_refill(nc, gfp_mask); - if (!page) + folio = page_frag_cache_refill(nc, gfp_mask); + if (!folio) return NULL; -#if (PAGE_SIZE < PAGE_FRAG_CACHE_MAX_SIZE) - /* if size can vary use size else just use PAGE_SIZE */ - size = nc->size; -#endif /* Even if we own the page, we do not use atomic_set(). * This would break get_page_unless_zero() users. */ - page_ref_add(page, PAGE_FRAG_CACHE_MAX_SIZE); + folio_ref_add(folio, PAGE_FRAG_CACHE_MAX_SIZE); /* reset page count bias and offset to start of new frag */ - nc->pfmemalloc = page_is_pfmemalloc(page); + nc->pfmemalloc = folio_is_pfmemalloc(folio); nc->pagecnt_bias = PAGE_FRAG_CACHE_MAX_SIZE + 1; - nc->offset = size; + nc->offset = folio_size(folio); } - offset = nc->offset - fragsz; - if (unlikely(offset < 0)) { - page = virt_to_page(nc->va); - - if (page_ref_count(page) != nc->pagecnt_bias) + offset = nc->offset; + if (unlikely(fragsz > offset)) { + /* Reuse the folio if everyone we gave it to has finished with it. */ + if (!folio_ref_sub_and_test(folio, nc->pagecnt_bias)) { + nc->folio = NULL; goto refill; + } + if (unlikely(nc->pfmemalloc)) { - page_ref_sub(page, nc->pagecnt_bias - 1); - __free_pages(page, compound_order(page)); + __folio_put(folio); + nc->folio = NULL; goto refill; } -#if (PAGE_SIZE < PAGE_FRAG_CACHE_MAX_SIZE) - /* if size can vary use size else just use PAGE_SIZE */ - size = nc->size; -#endif /* OK, page count is 0, we can safely set it */ - set_page_count(page, PAGE_FRAG_CACHE_MAX_SIZE + 1); + folio_set_count(folio, PAGE_FRAG_CACHE_MAX_SIZE + 1); /* reset page count bias and offset to start of new frag */ nc->pagecnt_bias = PAGE_FRAG_CACHE_MAX_SIZE + 1; - offset = size - fragsz; - if (unlikely(offset < 0)) { + offset = folio_size(folio); + if (unlikely(fragsz > offset)) { /* * The caller is trying to allocate a fragment * with fragsz > PAGE_SIZE but the cache isn't big @@ -107,15 +101,17 @@ void *page_frag_alloc_align(struct page_frag_cache *nc, * it could make memory pressure worse * so we simply return NULL here. */ + nc->offset = offset; return NULL; } } nc->pagecnt_bias--; + offset -= fragsz; offset &= align_mask; nc->offset = offset; - return nc->va + offset; + return folio_address(folio) + offset; } EXPORT_SYMBOL(page_frag_alloc_align); @@ -124,8 +120,6 @@ EXPORT_SYMBOL(page_frag_alloc_align); */ void page_frag_free(void *addr) { - struct page *page = virt_to_head_page(addr); - - __free_pages(page, compound_order(page)); + folio_put(virt_to_folio(addr)); } EXPORT_SYMBOL(page_frag_free);