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 kanga.kvack.org (kanga.kvack.org [205.233.56.17]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 7E410CCD193 for ; Thu, 23 Oct 2025 07:44:29 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id CADDE8E0005; Thu, 23 Oct 2025 03:44:28 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id C85858E0002; Thu, 23 Oct 2025 03:44:28 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id B9BF38E0005; Thu, 23 Oct 2025 03:44:28 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0017.hostedemail.com [216.40.44.17]) by kanga.kvack.org (Postfix) with ESMTP id A8E028E0002 for ; Thu, 23 Oct 2025 03:44:28 -0400 (EDT) Received: from smtpin12.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay02.hostedemail.com (Postfix) with ESMTP id 5C82313C04B for ; Thu, 23 Oct 2025 07:44:28 +0000 (UTC) X-FDA: 84028591416.12.98FBFCD Received: from invmail4.hynix.com (exvmail4.hynix.com [166.125.252.92]) by imf02.hostedemail.com (Postfix) with ESMTP id 6DF3F80002 for ; Thu, 23 Oct 2025 07:44:26 +0000 (UTC) Authentication-Results: imf02.hostedemail.com; spf=pass (imf02.hostedemail.com: domain of byungchul@sk.com designates 166.125.252.92 as permitted sender) smtp.mailfrom=byungchul@sk.com ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1761205466; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:content-type: content-transfer-encoding:in-reply-to:in-reply-to: references:references; bh=DhsDGEcJlnIM2loUQDP52Q83EiEbbdZT6r2iEDZkHqk=; b=5ViDJ0Sot3nMmyili+k3QgQDi+hIxERs4XIlr7mNW+wNte3Opl9bbxCX4eUuJw9mWXvFyf 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andrew+netdev@lunn.ch, edumazet@google.com, pabeni@redhat.com, akpm@linux-foundation.org, david@redhat.com, lorenzo.stoakes@oracle.com, Liam.Howlett@oracle.com, vbabka@suse.cz, rppt@kernel.org, surenb@google.com, mhocko@suse.com, horms@kernel.org, jackmanb@google.com, hannes@cmpxchg.org, ziy@nvidia.com, ilias.apalodimas@linaro.org, willy@infradead.org, brauner@kernel.org, kas@kernel.org, yuzhao@google.com, usamaarif642@gmail.com, baolin.wang@linux.alibaba.com, almasrymina@google.com, toke@redhat.com, asml.silence@gmail.com, bpf@vger.kernel.org, linux-rdma@vger.kernel.org, sfr@canb.auug.org.au, dw@davidwei.uk, ap420073@gmail.com, dtatulea@nvidia.com Subject: [RFC mm v4 1/2] page_pool: check if nmdesc->pp is !NULL to confirm its usage as pp for net_iov Date: Thu, 23 Oct 2025 16:44:09 +0900 Message-Id: <20251023074410.78650-2-byungchul@sk.com> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20251023074410.78650-1-byungchul@sk.com> References: <20251023074410.78650-1-byungchul@sk.com> 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z4WSnnDkXTnX53k0bRyQkj6wWP0bWYjdF2fzTTu/M5B3VrfPRA0AqLidbx1p9BjQ91yfTz95cNn81t/HOnO3r+FVtfBoYZH1tunU4S/iuHuBbkNMwv4sHCgVybtdNVs7n2ixQQOX5m18TM5GBxahnujvrPubd3EqQHLBs X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: ->pp_magic field in struct page is current used to identify if a page belongs to a page pool. However, ->pp_magic will be removed and page type bit in struct page e.g. PGTY_netpp should be used for that purpose. As a preparation, the check for net_iov, that is not page-backed, should avoid using ->pp_magic since net_iov doens't have to do with page type. Instead, nmdesc->pp can be used if a net_iov or its nmdesc belongs to a page pool, by making sure nmdesc->pp is NULL otherwise. For page-backed netmem, just leave unchanged as is, while for net_iov, make sure nmdesc->pp is initialized to NULL and use nmdesc->pp for the check. Signed-off-by: Byungchul Park --- net/core/devmem.c | 1 + net/core/netmem_priv.h | 8 ++++++++ net/core/page_pool.c | 16 ++++++++++++++-- 3 files changed, 23 insertions(+), 2 deletions(-) diff --git a/net/core/devmem.c b/net/core/devmem.c index d9de31a6cc7f..f81b700f1fd1 100644 --- a/net/core/devmem.c +++ b/net/core/devmem.c @@ -291,6 +291,7 @@ net_devmem_bind_dmabuf(struct net_device *dev, niov = &owner->area.niovs[i]; niov->type = NET_IOV_DMABUF; niov->owner = &owner->area; + niov->desc.pp = NULL; page_pool_set_dma_addr_netmem(net_iov_to_netmem(niov), net_devmem_get_dma_addr(niov)); if (direction == DMA_TO_DEVICE) diff --git a/net/core/netmem_priv.h b/net/core/netmem_priv.h index 23175cb2bd86..5561fd556bc5 100644 --- a/net/core/netmem_priv.h +++ b/net/core/netmem_priv.h @@ -22,6 +22,14 @@ static inline void netmem_clear_pp_magic(netmem_ref netmem) static inline bool netmem_is_pp(netmem_ref netmem) { + /* net_iov may be part of a page pool. For net_iov, ->pp in + * net_iov.desc can be used to determine if the pages belong to + * a page pool. Ensure that the ->pp either points to its page + * pool or is set to NULL if it does not. + */ + if (netmem_is_net_iov(netmem)) + return !!netmem_to_nmdesc(netmem)->pp; + return (netmem_get_pp_magic(netmem) & PP_MAGIC_MASK) == PP_SIGNATURE; } diff --git a/net/core/page_pool.c b/net/core/page_pool.c index 1a5edec485f1..2756b78754b0 100644 --- a/net/core/page_pool.c +++ b/net/core/page_pool.c @@ -699,7 +699,13 @@ s32 page_pool_inflight(const struct page_pool *pool, bool strict) void page_pool_set_pp_info(struct page_pool *pool, netmem_ref netmem) { netmem_set_pp(netmem, pool); - netmem_or_pp_magic(netmem, PP_SIGNATURE); + + /* For page-backed, pp_magic is used to identify if it's pp. + * For net_iov, it's ensured nmdesc->pp is non-NULL if it's pp + * and nmdesc->pp is NULL if it's not. + */ + if (!netmem_is_net_iov(netmem)) + netmem_or_pp_magic(netmem, PP_SIGNATURE); /* Ensuring all pages have been split into one fragment initially: * page_pool_set_pp_info() is only called once for every page when it @@ -714,7 +720,13 @@ void page_pool_set_pp_info(struct page_pool *pool, netmem_ref netmem) void page_pool_clear_pp_info(netmem_ref netmem) { - netmem_clear_pp_magic(netmem); + /* For page-backed, pp_magic is used to identify if it's pp. + * For net_iov, it's ensured nmdesc->pp is non-NULL if it's pp + * and nmdesc->pp is NULL if it's not. + */ + if (!netmem_is_net_iov(netmem)) + netmem_clear_pp_magic(netmem); + netmem_set_pp(netmem, NULL); } -- 2.17.1