From nobody Fri Sep 20 01:41:24 2024 Received: from szxga05-in.huawei.com (szxga05-in.huawei.com [45.249.212.191]) (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 5D35418F2FC; Thu, 8 Aug 2024 12:43:17 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=45.249.212.191 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1723120999; cv=none; b=hX8h6mziZuDy5EaqvGghkjcL0LyTPouImurOQ2NwyZeD/hcJnpvlIx5uy/NqFbCLK0ACWPIR3RCn2BYcI24VP0T7NtvDtPmQP7h/uq7fntO9+N1tKQMicuE3LvGmyLB/KI71pCx3MyTPxlMoqLtBMsx6E7GQ4fyx9PyNna/Dy/A= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1723120999; c=relaxed/simple; bh=1cNBvGfpE9Sd//Mt8Sdvn6uQfUFMHfBUMfGZXcP16wM=; h=From:To:CC:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=UZYUc3AekFkBgIa9GMejFU35nSqPLnUCl9wgORxb+WpCnLmxBov1vp9x/k2F2rjFfmr587znffpQRvUtJ5Chog32PPeTXwXY26i0KFcv/Wu/tx8/uPO9Q9aYELT1NUNodLdN4pwedL5/Wl/YOPJNmWdaGmtqN94ZBE5FNXoJF0c= 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=45.249.212.191 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 [172.19.163.44]) by szxga05-in.huawei.com (SkyGuard) with ESMTP id 4Wfmpn0QBnz1HG6M; Thu, 8 Aug 2024 20:40:17 +0800 (CST) Received: from dggpemf200006.china.huawei.com (unknown [7.185.36.61]) by mail.maildlp.com (Postfix) with ESMTPS id E4CE31400C9; Thu, 8 Aug 2024 20:43:14 +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; Thu, 8 Aug 2024 20:43:14 +0800 From: Yunsheng Lin To: , , CC: , , Yunsheng Lin , Alexander Duyck , Andrew Morton , Subject: [PATCH net-next v13 08/14] mm: page_frag: some minor refactoring before adding new API Date: Thu, 8 Aug 2024 20:37:08 +0800 Message-ID: <20240808123714.462740-9-linyunsheng@huawei.com> X-Mailer: git-send-email 2.30.0 In-Reply-To: <20240808123714.462740-1-linyunsheng@huawei.com> References: <20240808123714.462740-1-linyunsheng@huawei.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-ClientProxiedBy: dggems704-chm.china.huawei.com (10.3.19.181) To dggpemf200006.china.huawei.com (7.185.36.61) Content-Type: text/plain; charset="utf-8" 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_cach= e.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 en= coded_va) =20 static inline void page_frag_cache_init(struct page_frag_cache *nc) { - nc->encoded_va =3D 0; + memset(nc, 0, sizeof(*nc)); } =20 static inline bool page_frag_cache_is_pfmemalloc(struct page_frag_cache *n= c) diff --git a/mm/page_frag_cache.c b/mm/page_frag_cache.c index 2544b292375a..4e6b1c4684f0 100644 --- a/mm/page_frag_cache.c +++ b/mm/page_frag_cache.c @@ -19,8 +19,27 @@ #include #include "internal.h" =20 -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 =3D 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 =3D PAGE_FRAG_CACHE_MAX_ORDER; struct page *page =3D NULL; @@ -35,8 +54,8 @@ static struct page *__page_frag_cache_refill(struct page_= frag_cache *nc, if (unlikely(!page)) { page =3D alloc_pages_node(NUMA_NO_NODE, gfp, 0); if (unlikely(!page)) { - nc->encoded_va =3D 0; - return NULL; + memset(nc, 0, sizeof(*nc)); + return false; } =20 order =3D 0; @@ -45,7 +64,33 @@ static struct page *__page_frag_cache_refill(struct page= _frag_cache *nc, nc->encoded_va =3D encode_aligned_va(page_address(page), order, page_is_pfmemalloc(page)); =20 - 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 =3D PAGE_FRAG_CACHE_MAX_SIZE + 1; + nc->remaining =3D page_frag_cache_page_size(nc->encoded_va); + return true; } =20 void page_frag_cache_drain(struct page_frag_cache *nc) @@ -55,7 +100,7 @@ void page_frag_cache_drain(struct page_frag_cache *nc) =20 __page_frag_cache_drain(virt_to_head_page((void *)nc->encoded_va), nc->pagecnt_bias); - nc->encoded_va =3D 0; + memset(nc, 0, sizeof(*nc)); } EXPORT_SYMBOL(page_frag_cache_drain); =20 @@ -73,67 +118,44 @@ void *__page_frag_alloc_va_align(struct page_frag_cach= e *nc, unsigned int align_mask) { unsigned long encoded_va =3D nc->encoded_va; - unsigned int size, remaining; - struct page *page; - - if (unlikely(!encoded_va)) { -refill: - page =3D __page_frag_cache_refill(nc, gfp_mask); - if (!page) - return NULL; - - encoded_va =3D nc->encoded_va; - size =3D 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 =3D PAGE_FRAG_CACHE_MAX_SIZE + 1; - nc->remaining =3D size; - } else { - size =3D page_frag_cache_page_size(encoded_va); - } + unsigned int remaining; =20 remaining =3D 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 =3D virt_to_page((void *)encoded_va); =20 - 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 initializing and draining old + * cache, 'remaining >=3D fragsz' checking is enough to indicate there is + * enough available space for the new fragment allocation. + */ + if (likely(remaining >=3D fragsz)) { + nc->pagecnt_bias--; + nc->remaining =3D remaining - fragsz; =20 - /* 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); + } =20 - /* reset page count bias and remaining to start of new frag */ - nc->pagecnt_bias =3D PAGE_FRAG_CACHE_MAX_SIZE + 1; - remaining =3D 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; } =20 + if (unlikely(!__page_frag_cache_reload(nc, gfp_mask))) + return NULL; + + /* As the we are allocating fragment from cache by count-up way, the offs= et + * of allocated fragment from the just reloaded cache is zero, so remaini= ng + * aligning and offset calculation are not needed. + */ nc->pagecnt_bias--; - nc->remaining =3D remaining - fragsz; + nc->remaining -=3D fragsz; =20 - return encoded_page_address(encoded_va) + (size - remaining); + return encoded_page_address(nc->encoded_va); } EXPORT_SYMBOL(__page_frag_alloc_va_align); =20 --=20 2.33.0