From nobody Mon Oct 6 13:20:18 2025 Received: from invmail4.hynix.com (exvmail4.hynix.com [166.125.252.92]) by smtp.subspace.kernel.org (Postfix) with ESMTP id 0825D2F41; Mon, 21 Jul 2025 05:49:15 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=166.125.252.92 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1753076964; cv=none; b=SJc7VCctUHPjyw20VdPx9+aeDb+70zwjwqtjB+DnWZi3iG0VB+UcDsiX2SuWtQDek9qAwYo4VxGWTsobPRJeoXmPISEuNNldB5mxVQz+dYjR9ttO3eEuP3Igmq1viTZdD8Otc52g2oe5hizIHNHIjY+GtYr+3NnGlhBw/+4Sur0= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1753076964; c=relaxed/simple; bh=TARJJoAbi4u0J3Yl4vtNCmMWIScg1FJNbwOZRSclaO8=; h=From:To:Cc:Subject:Date:Message-Id; b=fLt7oZngF/gP7LG2Jmrq1srYr3mPGz/qtDUTskppMNwJZimDlEfn3zoWWLxNsJMmfCnM3UeJIaITR2s2HTmPKx6rDXUrapQy1Xx3/HY8x9GtGiQ+tbnfGOmlL+d6YnrAuP5xBs45GRPyBGnINJkUQqshpzv41+356JDNVwOL1Vg= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=sk.com; spf=pass smtp.mailfrom=sk.com; arc=none smtp.client-ip=166.125.252.92 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=sk.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=sk.com X-AuditID: a67dfc5b-669ff7000002311f-e4-687dd4da70c6 From: Byungchul Park To: linux-mm@kvack.org, netdev@vger.kernel.org Cc: linux-kernel@vger.kernel.org, kernel_team@skhynix.com, harry.yoo@oracle.com, ast@kernel.org, daniel@iogearbox.net, davem@davemloft.net, kuba@kernel.org, hawk@kernel.org, john.fastabend@gmail.com, sdf@fomichev.me, saeedm@nvidia.com, leon@kernel.org, tariqt@nvidia.com, mbloch@nvidia.com, 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 Subject: [PATCH] mm, page_pool: introduce a new page type for page pool in page type Date: Mon, 21 Jul 2025 14:49:03 +0900 Message-Id: <20250721054903.39833-1-byungchul@sk.com> X-Mailer: git-send-email 2.17.1 X-Brightmail-Tracker: H4sIAAAAAAAAAzXRa0hTcRjHcf/n/HfOabU4LamTBdLKAqErSU8UZe/+b4JAI6oXNfLYRjpt XtJqsdIsrZlpUrlFmrjmBY15m8tu21KzQNGs46W8hAZqWmrDW5havfvAl+f35uFopYT9OK0u VtTr1BEqRo7l35flben4YNBsvzq9AixlJQwUTybAkx6HDCxFVQgmpjpZmHteh2DcU8/AkHsM QX6elwZLUzKGX2XTNPTX9bFQbD8E3dYBDLXXq2nou93AgCl5hobnUyMsXHXYKLCUG1lorkqX wd3pAhqqjT0stDotDHwpmZPBgMuE4W1OIYYf2R4autODoS53FXjfDSPwlFVT4L31kIG2B04K slpyGfia3I2gxd2HIXv2BgPmK+kIZibn10YyJmRgfvOFDQ4k7uFRmlQUtlNEetFIkZqczyzJ tceRclsgSZNaaGIvSmWIfSyTJV0faxnScH8Gk5rePaTGMU4RU9IIQ372d2Ay+qKNObzyuHxf mBihjRf12/afkmvmOsXo7wcTBrMrkRFNBKWhJZzA7xLKnd9k/235UUovmOE3C5I0tWhffrtg y56Yt5yj+QpWKCmTFsNKPlR4mOKmFoz5AOH1g2G0YAUfJKTeafw36i8UP321eCzwJk5oqnVS f8Ma4bVNwhloaS7yKUJKrS4+Uq2N2LVVk6jTJmw9HRVpR/P/thpmTzjQWHOIC/EcUi1TRGOD RilTx8ckRrqQwNEqXwWpv6BRKsLUiRdEfdRJfVyEGONCazmsWq3Y6T0fpuTPqGPFs6IYLer/ V4pb4mdEl8TVheblB6Sk3Y7e/E3h9RUUyXhJ1p3uuqd75OJ8FOea5I/9Pe8rrYf9jx1x9kYS Q8rUp2EvVx93NDPg4u+T2Np0aCNuKSj1PM2r6rh90NwqxDKPDRu87tGcarN/0N4ELiokNLXk 2dD7nqz1F4+1X6YHjY/anTcnr20K351mUuEYjXpHIK2PUf8BcCp0b+sCAAA= X-Brightmail-Tracker: H4sIAAAAAAAAAzXRa0hTcRzGcf87Z+ccV4ODWR40UEYRWKlRo19aoRD0L1ILgigQXXpsQ6e2 qakgaGpe0OVtlTrBCM0bWdN0ilpt5rWLaMrUvGQoVKam07yRqdG7D3zhefMwhE0Tac8owiJ5 VZgsVEKJSJGPR9LRoU/xcrcRw0nQ1VRTULUSA08nDELQVdYjsKyO0LDZ0o5gsa2Dgh+mBQRP Hi8ToPuYTMJSzRoBU+2TNFTpvWG8bJqE5tQGAibvd1KQlbxOQMvqLA13DeUC0NUm0GAq7hJC b71GCPlrpQQ0JEzQ0N+ko2CselMI08YsEroKK0iY17YRMK7xhPaSfbDcM4OgraZBAMuZxRQM FDQJIK+vhIKvyeMI+kyTJGg30igoStQgWF/ZWpvNtgih6O0Y7XkYm2bmCFxXMSTA5tZuAW4s HKVxiT4K15Y74wxzH4H1lekU1i/k0vjzYDOFOx+tk7jxyyncaFgU4KykWQr/mhom8VzrAHXZ 9obodBAfqojmVa5nA0TyzRE+4qdXzHftS5SALNIMZM1w7AlON/+M2DbFHuLM5tUd27JuXLnW smURQ7B1NFddY94Je9irXPE9k2DbJHuQe1Mwg7YtZqVcek638N+oI1f1/DWRjZgSZFWJbBVh 0UqZIlTqog6Rx4YpYlwCw5V6tPVoWfxGjgFZ+s8bEcsgyW5xBBkvtxHKotWxSiPiGEJiK8Yd cXIbcZAsNo5XhfurokJ5tRE5MKTETnzxGh9gw96SRfIhPB/Bq/5XAWNtn4CsfCtEuwIf2rGj G5lT7s3lifWXrtj7PghRHe9cchJ9SAk+MOj/+1yIKWXY6O46KfUT21s3N/r0vPpTkern1ZSX kY89ilbeeTh2LSt72zRIeHPYwSmtMLiUQ52p700v9sdJz6SV5Xrf1hy5oJRprhdr/cHOM/Xb 3juVWWKvscIxCamWy445Eyq17C8y1HQ5zQIAAA== X-CFilter-Loop: Reflected Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Hi, I focused on converting the existing APIs accessing ->pp_magic field to page type APIs. However, yes. Additional works would better be considered on top like: 1. Adjust how to store and retrieve dma index. Maybe network guys can work better on top. 2. Move the sanity check for page pool in mm/page_alloc.c to on free. Byungchul Suggested-by: David Hildenbrand Suggested-by: Pavel Begunkov ---8<--- From 7d207a1b3e9f4ff2a72f5b54b09e3ed0c4aaaca3 Mon Sep 17 00:00:00 2001 From: Byungchul Park Date: Mon, 21 Jul 2025 14:05:20 +0900 Subject: [PATCH] mm, page_pool: introduce a new page type for page pool in = page type ->pp_magic field in struct page is current used to identify if a page belongs to a page pool. However, page type e.i. PGTY_netpp can be used for that purpose. Use the page type APIs e.g. PageNetpp(), __SetPageNetpp(), and __ClearPageNetpp() instead, and remove the existing APIs accessing ->pp_magic e.g. page_pool_page_is_pp(), netmem_or_pp_magic(), and netmem_clear_pp_magic() since they are totally replaced. This work was inspired by the following link by Pavel: [1] https://lore.kernel.org/all/582f41c0-2742-4400-9c81-0d46bf4e8314@gmail.= com/ Suggested-by: Pavel Begunkov Signed-off-by: Byungchul Park --- .../net/ethernet/mellanox/mlx5/core/en/xdp.c | 2 +- include/linux/mm.h | 28 ++----------------- include/linux/page-flags.h | 6 ++++ include/net/netmem.h | 2 +- mm/page_alloc.c | 4 +-- net/core/netmem_priv.h | 16 ++--------- net/core/page_pool.c | 10 +++++-- 7 files changed, 24 insertions(+), 44 deletions(-) diff --git a/drivers/net/ethernet/mellanox/mlx5/core/en/xdp.c b/drivers/net= /ethernet/mellanox/mlx5/core/en/xdp.c index 5d51600935a6..def274f5c1ca 100644 --- a/drivers/net/ethernet/mellanox/mlx5/core/en/xdp.c +++ b/drivers/net/ethernet/mellanox/mlx5/core/en/xdp.c @@ -707,7 +707,7 @@ static void mlx5e_free_xdpsq_desc(struct mlx5e_xdpsq *s= q, xdpi =3D mlx5e_xdpi_fifo_pop(xdpi_fifo); page =3D xdpi.page.page; =20 - /* No need to check page_pool_page_is_pp() as we + /* No need to check PageNetpp() as we * know this is a page_pool page. */ page_pool_recycle_direct(pp_page_to_nmdesc(page)->pp, diff --git a/include/linux/mm.h b/include/linux/mm.h index ae50c1641bed..736061749535 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -4135,10 +4135,9 @@ int arch_lock_shadow_stack_status(struct task_struct= *t, unsigned long status); * DMA mapping IDs for page_pool * * When DMA-mapping a page, page_pool allocates an ID (from an xarray) and - * stashes it in the upper bits of page->pp_magic. We always want to be ab= le to - * unambiguously identify page pool pages (using page_pool_page_is_pp()). = Non-PP - * pages can have arbitrary kernel pointers stored in the same field as pp= _magic - * (since it overlaps with page->lru.next), so we must ensure that we cann= ot + * stashes it in the upper bits of page->pp_magic. Non-PP pages can have + * arbitrary kernel pointers stored in the same field as pp_magic (since + * it overlaps with page->lru.next), so we must ensure that we cannot * mistake a valid kernel pointer with any of the values we write into this * field. * @@ -4168,25 +4167,4 @@ int arch_lock_shadow_stack_status(struct task_struct= *t, unsigned long status); =20 #define PP_DMA_INDEX_MASK GENMASK(PP_DMA_INDEX_BITS + PP_DMA_INDEX_SHIFT -= 1, \ PP_DMA_INDEX_SHIFT) - -/* Mask used for checking in page_pool_page_is_pp() below. page->pp_magic = is - * OR'ed with PP_SIGNATURE after the allocation in order to preserve bit 0= for - * the head page of compound page and bit 1 for pfmemalloc page, as well a= s the - * bits used for the DMA index. page_is_pfmemalloc() is checked in - * __page_pool_put_page() to avoid recycling the pfmemalloc page. - */ -#define PP_MAGIC_MASK ~(PP_DMA_INDEX_MASK | 0x3UL) - -#ifdef CONFIG_PAGE_POOL -static inline bool page_pool_page_is_pp(const struct page *page) -{ - return (page->pp_magic & PP_MAGIC_MASK) =3D=3D PP_SIGNATURE; -} -#else -static inline bool page_pool_page_is_pp(const struct page *page) -{ - return false; -} -#endif - #endif /* _LINUX_MM_H */ diff --git a/include/linux/page-flags.h b/include/linux/page-flags.h index 4fe5ee67535b..906ba7c9e372 100644 --- a/include/linux/page-flags.h +++ b/include/linux/page-flags.h @@ -957,6 +957,7 @@ enum pagetype { PGTY_zsmalloc =3D 0xf6, PGTY_unaccepted =3D 0xf7, PGTY_large_kmalloc =3D 0xf8, + PGTY_netpp =3D 0xf9, =20 PGTY_mapcount_underflow =3D 0xff }; @@ -1101,6 +1102,11 @@ PAGE_TYPE_OPS(Zsmalloc, zsmalloc, zsmalloc) PAGE_TYPE_OPS(Unaccepted, unaccepted, unaccepted) FOLIO_TYPE_OPS(large_kmalloc, large_kmalloc) =20 +/* + * Marks page_pool allocated pages. + */ +PAGE_TYPE_OPS(Netpp, netpp, netpp) + /** * PageHuge - Determine if the page belongs to hugetlbfs * @page: The page to test. diff --git a/include/net/netmem.h b/include/net/netmem.h index f7dacc9e75fd..3667334e16e7 100644 --- a/include/net/netmem.h +++ b/include/net/netmem.h @@ -298,7 +298,7 @@ static inline struct net_iov *__netmem_clear_lsb(netmem= _ref netmem) */ #define pp_page_to_nmdesc(p) \ ({ \ - DEBUG_NET_WARN_ON_ONCE(!page_pool_page_is_pp(p)); \ + DEBUG_NET_WARN_ON_ONCE(!PageNetpp(p)); \ __pp_page_to_nmdesc(p); \ }) =20 diff --git a/mm/page_alloc.c b/mm/page_alloc.c index 2ef3c07266b3..71c7666e48a9 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -898,7 +898,7 @@ static inline bool page_expected_state(struct page *pag= e, #ifdef CONFIG_MEMCG page->memcg_data | #endif - page_pool_page_is_pp(page) | + PageNetpp(page) | (page->flags & check_flags))) return false; =20 @@ -925,7 +925,7 @@ static const char *page_bad_reason(struct page *page, u= nsigned long flags) if (unlikely(page->memcg_data)) bad_reason =3D "page still charged to cgroup"; #endif - if (unlikely(page_pool_page_is_pp(page))) + if (unlikely(PageNetpp(page))) bad_reason =3D "page_pool leak"; return bad_reason; } diff --git a/net/core/netmem_priv.h b/net/core/netmem_priv.h index cd95394399b4..39a97703d9ed 100644 --- a/net/core/netmem_priv.h +++ b/net/core/netmem_priv.h @@ -8,21 +8,11 @@ static inline unsigned long netmem_get_pp_magic(netmem_re= f netmem) return __netmem_clear_lsb(netmem)->pp_magic & ~PP_DMA_INDEX_MASK; } =20 -static inline void netmem_or_pp_magic(netmem_ref netmem, unsigned long pp_= magic) -{ - __netmem_clear_lsb(netmem)->pp_magic |=3D pp_magic; -} - -static inline void netmem_clear_pp_magic(netmem_ref netmem) -{ - WARN_ON_ONCE(__netmem_clear_lsb(netmem)->pp_magic & PP_DMA_INDEX_MASK); - - __netmem_clear_lsb(netmem)->pp_magic =3D 0; -} - static inline bool netmem_is_pp(netmem_ref netmem) { - return (netmem_get_pp_magic(netmem) & PP_MAGIC_MASK) =3D=3D PP_SIGNATURE; + if (netmem_is_net_iov(netmem)) + return true; + return PageNetpp(__netmem_to_page(netmem)); } =20 static inline void netmem_set_pp(netmem_ref netmem, struct page_pool *pool) diff --git a/net/core/page_pool.c b/net/core/page_pool.c index 05e2e22a8f7c..0a10f3026faa 100644 --- a/net/core/page_pool.c +++ b/net/core/page_pool.c @@ -654,7 +654,6 @@ s32 page_pool_inflight(const struct page_pool *pool, bo= ol 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); =20 /* Ensuring all pages have been split into one fragment initially: * page_pool_set_pp_info() is only called once for every page when it @@ -665,12 +664,19 @@ void page_pool_set_pp_info(struct page_pool *pool, ne= tmem_ref netmem) page_pool_fragment_netmem(netmem, 1); if (pool->has_init_callback) pool->slow.init_callback(netmem, pool->slow.init_arg); + + if (netmem_is_net_iov(netmem)) + return; + __SetPageNetpp(__netmem_to_page(netmem)); } =20 void page_pool_clear_pp_info(netmem_ref netmem) { - netmem_clear_pp_magic(netmem); netmem_set_pp(netmem, NULL); + + if (netmem_is_net_iov(netmem)) + return; + __ClearPageNetpp(__netmem_to_page(netmem)); } =20 static __always_inline void __page_pool_release_netmem_dma(struct page_poo= l *pool, --=20 2.17.1