From patchwork Wed Jul 31 12:44:58 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Yunsheng Lin X-Patchwork-Id: 13748730 X-Patchwork-Delegate: kuba@kernel.org Received: from szxga03-in.huawei.com (szxga03-in.huawei.com [45.249.212.189]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 8E6391BA874; Wed, 31 Jul 2024 12:51:00 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=45.249.212.189 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1722430262; cv=none; b=B/YiRb0k2YbLJLJ2DuulAwcrWlNn/tZ2CJprbUmltXad+6056AlJqSjitZ4twz0LXgxVJnV12ymlLv9tDofF+/5Ge817RPLFjz99vZTlaGYpoBIvy3oMaivT2Rq/vZh1UJUFIJKqbRi3Yjpn/mCK86j49J/H2iizRa8WKV33RIc= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1722430262; c=relaxed/simple; bh=JPkz60JVkHO/lahG4J4VX8F6Zc+qis3p9m9cOZxtpUI=; h=From:To:CC:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=Tn3OaIbp2+WDCprLIf+JKaFLhsrGE1NhQdI5EUyTKiScZumfJ75w0YLC9kx3wMXvUY4nPc5Pbyyf6jXrHA5FsE8Uk0rMzVQ8hFzZff/SINCnqUFgSbqjz6yA/qOCJu4zzLox+12t8yAPq0QcifL3vdz6DgIUnHuAWqpdaCGDS8Y= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=huawei.com; spf=pass smtp.mailfrom=huawei.com; arc=none smtp.client-ip=45.249.212.189 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=huawei.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=huawei.com Received: from mail.maildlp.com (unknown [172.19.163.174]) by szxga03-in.huawei.com (SkyGuard) with ESMTP id 4WYsKq4M81zQnC9; Wed, 31 Jul 2024 20:46:39 +0800 (CST) Received: from dggpemf200006.china.huawei.com (unknown [7.185.36.61]) by mail.maildlp.com (Postfix) with ESMTPS id AAEEE140360; Wed, 31 Jul 2024 20:50:58 +0800 (CST) Received: from localhost.localdomain (10.90.30.45) by dggpemf200006.china.huawei.com (7.185.36.61) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.1544.11; Wed, 31 Jul 2024 20:50:58 +0800 From: Yunsheng Lin To: , , CC: , , Yunsheng Lin , Alexander Duyck , Andrew Morton , Subject: [PATCH net-next v12 08/14] mm: page_frag: some minor refactoring before adding new API Date: Wed, 31 Jul 2024 20:44:58 +0800 Message-ID: <20240731124505.2903877-9-linyunsheng@huawei.com> X-Mailer: git-send-email 2.30.0 In-Reply-To: <20240731124505.2903877-1-linyunsheng@huawei.com> References: <20240731124505.2903877-1-linyunsheng@huawei.com> Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-ClientProxiedBy: dggems705-chm.china.huawei.com (10.3.19.182) To dggpemf200006.china.huawei.com (7.185.36.61) X-Patchwork-Delegate: kuba@kernel.org Refactor common codes from __page_frag_alloc_va_align() to __page_frag_cache_reload(), so that the new API can make use of them. CC: Alexander Duyck Signed-off-by: Yunsheng Lin --- include/linux/page_frag_cache.h | 2 +- mm/page_frag_cache.c | 138 ++++++++++++++++++-------------- 2 files changed, 81 insertions(+), 59 deletions(-) diff --git a/include/linux/page_frag_cache.h b/include/linux/page_frag_cache.h index 4ce924eaf1b1..0abffdd10a1c 100644 --- a/include/linux/page_frag_cache.h +++ b/include/linux/page_frag_cache.h @@ -52,7 +52,7 @@ static inline void *encoded_page_address(unsigned long encoded_va) static inline void page_frag_cache_init(struct page_frag_cache *nc) { - nc->encoded_va = 0; + memset(nc, 0, sizeof(*nc)); } static inline bool page_frag_cache_is_pfmemalloc(struct page_frag_cache *nc) diff --git a/mm/page_frag_cache.c b/mm/page_frag_cache.c index 2544b292375a..aa6eef55bb9c 100644 --- a/mm/page_frag_cache.c +++ b/mm/page_frag_cache.c @@ -19,8 +19,27 @@ #include #include "internal.h" -static struct page *__page_frag_cache_refill(struct page_frag_cache *nc, - gfp_t gfp_mask) +static bool __page_frag_cache_reuse(unsigned long encoded_va, + unsigned int pagecnt_bias) +{ + struct page *page; + + page = virt_to_page((void *)encoded_va); + if (!page_ref_sub_and_test(page, pagecnt_bias)) + return false; + + if (unlikely(encoded_page_pfmemalloc(encoded_va))) { + free_unref_page(page, encoded_page_order(encoded_va)); + return false; + } + + /* OK, page count is 0, we can safely set it */ + set_page_count(page, PAGE_FRAG_CACHE_MAX_SIZE + 1); + return true; +} + +static bool __page_frag_cache_refill(struct page_frag_cache *nc, + gfp_t gfp_mask) { unsigned long order = PAGE_FRAG_CACHE_MAX_ORDER; struct page *page = NULL; @@ -35,8 +54,8 @@ static struct page *__page_frag_cache_refill(struct page_frag_cache *nc, if (unlikely(!page)) { page = alloc_pages_node(NUMA_NO_NODE, gfp, 0); if (unlikely(!page)) { - nc->encoded_va = 0; - return NULL; + memset(nc, 0, sizeof(*nc)); + return false; } order = 0; @@ -45,7 +64,33 @@ static struct page *__page_frag_cache_refill(struct page_frag_cache *nc, nc->encoded_va = encode_aligned_va(page_address(page), order, page_is_pfmemalloc(page)); - return page; + /* 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); + + return true; +} + +/* Reload cache by reusing the old cache if it is possible, or + * refilling from the page allocator. + */ +static bool __page_frag_cache_reload(struct page_frag_cache *nc, + gfp_t gfp_mask) +{ + if (likely(nc->encoded_va)) { + if (__page_frag_cache_reuse(nc->encoded_va, nc->pagecnt_bias)) + goto out; + } + + if (unlikely(!__page_frag_cache_refill(nc, gfp_mask))) + return false; + +out: + /* reset page count bias and remaining to start of new frag */ + nc->pagecnt_bias = PAGE_FRAG_CACHE_MAX_SIZE + 1; + nc->remaining = page_frag_cache_page_size(nc->encoded_va); + return true; } void page_frag_cache_drain(struct page_frag_cache *nc) @@ -55,7 +100,7 @@ void page_frag_cache_drain(struct page_frag_cache *nc) __page_frag_cache_drain(virt_to_head_page((void *)nc->encoded_va), nc->pagecnt_bias); - nc->encoded_va = 0; + memset(nc, 0, sizeof(*nc)); } EXPORT_SYMBOL(page_frag_cache_drain); @@ -73,67 +118,44 @@ void *__page_frag_alloc_va_align(struct page_frag_cache *nc, unsigned int align_mask) { unsigned long encoded_va = nc->encoded_va; - unsigned int size, remaining; - struct page *page; - - if (unlikely(!encoded_va)) { -refill: - page = __page_frag_cache_refill(nc, gfp_mask); - if (!page) - return NULL; - - encoded_va = nc->encoded_va; - size = page_frag_cache_page_size(encoded_va); - - /* 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); - - /* reset page count bias and remaining to start of new frag */ - nc->pagecnt_bias = PAGE_FRAG_CACHE_MAX_SIZE + 1; - nc->remaining = size; - } else { - size = page_frag_cache_page_size(encoded_va); - } + unsigned int remaining; remaining = nc->remaining & align_mask; - if (unlikely(remaining < fragsz)) { - if (unlikely(fragsz > PAGE_SIZE)) { - /* - * The caller is trying to allocate a fragment - * with fragsz > PAGE_SIZE but the cache isn't big - * enough to satisfy the request, this may - * happen in low memory conditions. - * We don't release the cache page because - * it could make memory pressure worse - * so we simply return NULL here. - */ - return NULL; - } - - page = virt_to_page((void *)encoded_va); - if (!page_ref_sub_and_test(page, nc->pagecnt_bias)) - goto refill; - - if (unlikely(encoded_page_pfmemalloc(encoded_va))) { - free_unref_page(page, encoded_page_order(encoded_va)); - goto refill; - } + /* As we have ensured remaining is zero when initiating and draining old + * cache, 'remaining >= fragsz' checking is enough to indicate there is + * enough available space for the new fragment allocation. + */ + if (likely(remaining >= fragsz)) { + nc->pagecnt_bias--; + nc->remaining = remaining - fragsz; - /* OK, page count is 0, we can safely set it */ - set_page_count(page, PAGE_FRAG_CACHE_MAX_SIZE + 1); + return encoded_page_address(encoded_va) + + (page_frag_cache_page_size(encoded_va) - remaining); + } - /* reset page count bias and remaining to start of new frag */ - nc->pagecnt_bias = PAGE_FRAG_CACHE_MAX_SIZE + 1; - remaining = size; + if (unlikely(fragsz > PAGE_SIZE)) { + /* + * The caller is trying to allocate a fragment with + * fragsz > PAGE_SIZE but the cache isn't big enough to satisfy + * the request, this may happen in low memory conditions. We don't + * release the cache page because it could make memory pressure + * worse so we simply return NULL here. + */ + return NULL; } + if (unlikely(!__page_frag_cache_reload(nc, gfp_mask))) + return NULL; + + /* As the we are allocating fragment from cache by count-up way, the offset + * of allocated fragment from the just reloaded cache is zero, so remaining + * aligning and offset calculation are not needed. + */ nc->pagecnt_bias--; - nc->remaining = remaining - fragsz; + nc->remaining -= fragsz; - return encoded_page_address(encoded_va) + (size - remaining); + return encoded_page_address(nc->encoded_va); } EXPORT_SYMBOL(__page_frag_alloc_va_align);