From nobody Mon Feb 9 05:59:44 2026 Received: from invmail4.hynix.com (exvmail4.hynix.com [166.125.252.92]) by smtp.subspace.kernel.org (Postfix) with ESMTP id 1AED624634F; Thu, 23 Oct 2025 07:44:57 +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=1761205501; cv=none; b=NnEDbsIaAHtc8F4Fo38MC/z4X95Mb5aUEHb5NHlWpzYPOhmjjcXYcOVdeVQw1ZqL/XmpTUyF1uRL51z1rxE5aaAAuo6D1fTjFIcPM47GH0tsXkoQpRQUM1wisUcHS+6LmAM/U2Jj1/SG6ct8IMHJ4qvoyTGVQcQlM3E2EYtQ6xQ= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1761205501; c=relaxed/simple; bh=bcO0IIMDLYsyIp56WuxfH+4Zuw9yuTNlc7vmAUjDf2s=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References; b=OXw+BrRO9jA0BLn10RlZy55Grs10CXg910BJatAHU0d6ccygVxEtFNAIl9Hr9cpukh4mZB0DoVsQRVZt53lNQMDustDRgibGgipgIMepfZb6A4SohzDNJbn91Z0/AqjsUxgL1fd+nBY74Qdf+JwNSsXyz5Adyx+r6g8hcBTXOsQ= 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-c2dff70000001609-d6-68f9dcf85542 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, sfr@canb.auug.org.au, dw@davidwei.uk, ap420073@gmail.com, dtatulea@nvidia.com Subject: [RFC mm v4 2/2] mm: introduce a new page type for page pool in page type Date: Thu, 23 Oct 2025 16:44:10 +0900 Message-Id: <20251023074410.78650-3-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> X-Brightmail-Tracker: H4sIAAAAAAAAAzWSa0hTcRjG+59zds5xuDitzNMNZZaBkV2Y8VoREgXHoJtBURE52sGNdMZm S4NIa1GZmlqG2YSJNE0Nc1q7oGLzXlFzXZiUrmYZaVl4GW5Wtil9+/E8z/v79NK4OEewnFaq Mni1SpYqIYWE8EdoxXrfB59i45VcAejr60ionc6Eqo8WAfjqvmKgr3mCYNL3noLZli4EEx3d JIy2jyOorPDioH+lI2Cq3o+D1fYVwUjpQxK+dHkoqDXtBbdxmIDmq2YcPDd7SMjXzeDQ4huj 4JKlOiBuzKbA8aRAALf993EwZ3+k4LVNT8Jg3awAhu35BPSWPSDgV0kHDu6CBOgyLAXv8+8I OurNGHjzykl4e9eGweOWtxTcchpIGNK5ETjbPQSU/L5Gwr2cAgQz0wHlWOGkAO51DlIJsVyO y0Vy7d9/4lzTg36Me1daRHCu1mcYZy0boDiD6SzXWB3D5bqcOGequU5ypvFiivvwrpnkekpn CM76KZ6zWiYwLv/yGHkg7Jhwu5xPVWp59YYdyUJFyVPpmTuJma0vGrBs5NiWi0JolpGyb5rc glxEz/Hfz4eDMcmsZV0uHx7kJcxGtrpkMsBCGmdu0Oz71oa5YjFzkO3vzsOCtwSzhv38JywY i5g4Nsc5gs/rI9jaR21zHMJsYXv/dlJBFgc2jiI/Nb/poFlzT9I8L2OfVruIQiQyoAU1SKxU adNkylRprCJLpcyMPZWeZkKBxzBe+H3cgsYdh+yIoZEkVJTQPa0QC2RaTVaaHbE0Llki0h4N RCK5LOs8r04/qT6bymvsaAVNSMJFm73n5GImRZbBn+b5M7z6f4vRIcuzUZIxnPokpyy98pSU vq74RNlpfPbUosQBaflUpDHakzFUWecdLN/3Mm2nXxkxujU6ovCVTb6waV3R4+uh3pHJsF1R 305s9tsaQjoPr99vqDrfE6FS67pL+72rI/OGe/HkRUlRawxtY1O7VxaXsca46dC+basoh1Xy 4shFMb2njZAQGoVsUwyu1sj+AaCCXvwUAwAA X-Brightmail-Tracker: H4sIAAAAAAAAAzWRf0yMcRzHfZ/nued5Oo5np/LIjN0Ya+uHTfaxrDW/etgYs7EYOjx1R7/c qXVouspwlMJZ0k2Y3HWRLv1ULd1VkpJrtWv9VAlJUWldpVxt/nvt/eufN42L+wk3Wh5+gVeE S0MlpJAQ7vdN8JjssMu8X15fBxm5OSQYJ2PgeU+xAOw5XzHIyC5EMG5vp2CuvAbBmKWWhB/m UQRPH0/gkPExkYA/uVM4lJR+RTCY9oKELzW9FBhN+6A7a4CAsmtFOPTefkdCUuI0DuX2YQri i/WO4fw4Csy6OgE0FSYL4N7UMxyK4nooaC7NIKErZ04AA1VJBNSlGwj4pbXg0J3sDzWZrjBR P4TAkluEwcQtHQktD0oxKChvoeCuNZOEvsRuBFZzLwHameskPFQnI5iedEwOp4wL4GF1F+Xv xaltNpIzD43g3GtDG8a1pqUSnK3iPcaVpHdSXKYpisvXu3MamxXnTNk3SM40eofiOlrLSO5d 2jTBlXzeypUUj2FcUsIwecD1qHDbGT5UHs0rvPyChDLt282R9/fEVHzIw+JQk68G0TTLbGZn +w9rkBNNMhtYm82Oz7Mz483qteMOFtI4c5Nm2yvyFozlzEG2rfYWNt8lmPVs/1+XeVnE+LBq 6+BChGXWsMZXlQvsxGxh62arqXkWOzJNqVNUChJmokXZyFkeHh0mlYf6eCrPyVTh8hjP0xFh JuT4Pit2JrUYjTcHVCGGRpIlIv/aSZlYII1WqsKqEEvjEmdRdKBDEp2Rqi7yioiTiqhQXlmF VtGEZIVo7xE+SMyESC/w53g+klf8dzHayS0ONQj9zttUszoPTdm6gN2Ww6fEjW25G080XAnu WBbYaF15VX9sR7z657clhp0uvtO7rN/fL2a0eW98nDWV62++PHTZYoidre/sVe0JFvQJDzbv f6PrHth+98naNsG+CLEuZIU5a+mj0d8XF41s7PDoUT/yT398tsAY+On4l4aUUuOxS6slhFIm 3eSOK5TSfxAth6D3AgAA 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" ->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.i. PGTY_netpp can be used for that purpose. Introduce and 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(). This work was inspired by the following link: [1] https://lore.kernel.org/all/582f41c0-2742-4400-9c81-0d46bf4e8314@gmail.= com/ While at it, move the sanity check for page pool to on free. Suggested-by: David Hildenbrand Co-developed-by: Pavel Begunkov Signed-off-by: Pavel Begunkov Signed-off-by: Byungchul Park Acked-by: David Hildenbrand Acked-by: Zi Yan Acked-by: Mina Almasry --- Hi Mina, I dropped your Reviewed-by tag since there are updates on some comments in network part. Can I still keep your Reviewed-by? Byungchul --- .../net/ethernet/mellanox/mlx5/core/en/xdp.c | 2 +- include/linux/mm.h | 27 +++---------------- include/linux/page-flags.h | 6 +++++ include/net/netmem.h | 2 +- mm/page_alloc.c | 8 +++--- net/core/netmem_priv.h | 17 +++--------- net/core/page_pool.c | 14 +++++----- 7 files changed, 25 insertions(+), 51 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 b6fdf3557807..f5155f1c75f5 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -4361,10 +4361,9 @@ 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. * @@ -4399,26 +4398,6 @@ int arch_lock_shadow_stack_status(struct task_struct= *t, unsigned long status); #define PP_DMA_INDEX_MASK GENMASK(PP_DMA_INDEX_BITS + PP_DMA_INDEX_SHIFT -= 1, \ PP_DMA_INDEX_SHIFT) =20 -/* 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 - #define PAGE_SNAPSHOT_FAITHFUL (1 << 0) #define PAGE_SNAPSHOT_PG_BUDDY (1 << 1) #define PAGE_SNAPSHOT_PG_IDLE (1 << 2) diff --git a/include/linux/page-flags.h b/include/linux/page-flags.h index 0091ad1986bf..edf5418c91dd 100644 --- a/include/linux/page-flags.h +++ b/include/linux/page-flags.h @@ -934,6 +934,7 @@ 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 }; @@ -1078,6 +1079,11 @@ 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 651e2c62d1dd..0ec4c7561081 100644 --- a/include/net/netmem.h +++ b/include/net/netmem.h @@ -260,7 +260,7 @@ static inline unsigned long netmem_pfn_trace(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 fb91c566327c..c69ed3741bbc 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -1042,7 +1042,6 @@ static inline bool page_expected_state(struct page *p= age, #ifdef CONFIG_MEMCG page->memcg_data | #endif - page_pool_page_is_pp(page) | (page->flags.f & check_flags))) return false; =20 @@ -1069,8 +1068,6 @@ static const char *page_bad_reason(struct page *page,= unsigned long flags) if (unlikely(page->memcg_data)) bad_reason =3D "page still charged to cgroup"; #endif - if (unlikely(page_pool_page_is_pp(page))) - bad_reason =3D "page_pool leak"; return bad_reason; } =20 @@ -1379,9 +1376,12 @@ __always_inline bool free_pages_prepare(struct page = *page, mod_mthp_stat(order, MTHP_STAT_NR_ANON, -1); folio->mapping =3D NULL; } - if (unlikely(page_has_type(page))) + if (unlikely(page_has_type(page))) { + /* networking expects to clear its page type before releasing */ + WARN_ON_ONCE(PageNetpp(page)); /* Reset the page_type (which overlays _mapcount) */ page->page_type =3D UINT_MAX; + } =20 if (is_check_pages_enabled()) { if (free_page_is_bad(page)) diff --git a/net/core/netmem_priv.h b/net/core/netmem_priv.h index 5561fd556bc5..664a9fe87c66 100644 --- a/net/core/netmem_priv.h +++ b/net/core/netmem_priv.h @@ -8,18 +8,6 @@ static inline unsigned long netmem_get_pp_magic(netmem_ref= netmem) return netmem_to_nmdesc(netmem)->pp_magic & ~PP_DMA_INDEX_MASK; } =20 -static inline void netmem_or_pp_magic(netmem_ref netmem, unsigned long pp_= magic) -{ - netmem_to_nmdesc(netmem)->pp_magic |=3D pp_magic; -} - -static inline void netmem_clear_pp_magic(netmem_ref netmem) -{ - WARN_ON_ONCE(netmem_to_nmdesc(netmem)->pp_magic & PP_DMA_INDEX_MASK); - - netmem_to_nmdesc(netmem)->pp_magic =3D 0; -} - static inline bool netmem_is_pp(netmem_ref netmem) { /* net_iov may be part of a page pool. For net_iov, ->pp in @@ -30,7 +18,10 @@ static inline bool netmem_is_pp(netmem_ref netmem) if (netmem_is_net_iov(netmem)) return !!netmem_to_nmdesc(netmem)->pp; =20 - return (netmem_get_pp_magic(netmem) & PP_MAGIC_MASK) =3D=3D PP_SIGNATURE; + /* For system memory, page type in struct page can be used to + * determine if the pages belong to a page pool. + */ + 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 2756b78754b0..c43a0f4479d4 100644 --- a/net/core/page_pool.c +++ b/net/core/page_pool.c @@ -700,12 +700,11 @@ void page_pool_set_pp_info(struct page_pool *pool, ne= tmem_ref netmem) { netmem_set_pp(netmem, pool); =20 - /* 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. + /* For system memory, page type in struct page is used to + * determine if the pages belong to a page pool. */ if (!netmem_is_net_iov(netmem)) - netmem_or_pp_magic(netmem, PP_SIGNATURE); + __SetPageNetpp(__netmem_to_page(netmem)); =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 @@ -720,12 +719,11 @@ void page_pool_set_pp_info(struct page_pool *pool, ne= tmem_ref netmem) =20 void page_pool_clear_pp_info(netmem_ref 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. + /* For system memory, page type in struct page is used to + * determine if the pages belong to a page pool. */ if (!netmem_is_net_iov(netmem)) - netmem_clear_pp_magic(netmem); + __ClearPageNetpp(__netmem_to_page(netmem)); =20 netmem_set_pp(netmem, NULL); } --=20 2.17.1