Rebasing on the latest linux-next/master is required. Otherwise, a build fail is observed. Sorry about the noise. Changes from v1: 1. Rebase on linux-next. 2. Initialize net_iov->pp = NULL when allocating net_iov in net_devmem_bind_dmabuf() and io_zcrx_create_area(). 3. Use ->pp for net_iov to identify if it's pp rather than always consider net_iov as pp. 4. Add Suggested-by: David Hildenbrand . ---8<--- From 26c9a731f388b788d6ea972c313bc8da8831412b Mon Sep 17 00:00:00 2001 From: Byungchul Park Date: Mon, 28 Jul 2025 17:09:20 +0900 Subject: [PATCH v2 rebase as of Jul 28] 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, ->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(). For net_iov, use ->pp to identify if it's pp, with making sure that ->pp is NULL for non-pp net_iov. 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 Signed-off-by: Byungchul Park --- .../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 +- io_uring/zcrx.c | 1 + mm/page_alloc.c | 7 +++-- net/core/devmem.c | 1 + net/core/netmem_priv.h | 23 +++++++--------- net/core/page_pool.c | 10 +++++-- 9 files changed, 34 insertions(+), 45 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 *sq, xdpi = mlx5e_xdpi_fifo_pop(xdpi_fifo); page = xdpi.page.page; - /* 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 0d4ee569aa6b..d01b296e7184 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -4171,10 +4171,9 @@ 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 able 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 cannot + * 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. * @@ -4205,26 +4204,6 @@ 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) -/* 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 as 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) == 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 8d3fa3a91ce4..84247e39e9e7 100644 --- a/include/linux/page-flags.h +++ b/include/linux/page-flags.h @@ -933,6 +933,7 @@ enum pagetype { PGTY_zsmalloc = 0xf6, PGTY_unaccepted = 0xf7, PGTY_large_kmalloc = 0xf8, + PGTY_netpp = 0xf9, PGTY_mapcount_underflow = 0xff }; @@ -1077,6 +1078,11 @@ PAGE_TYPE_OPS(Zsmalloc, zsmalloc, zsmalloc) PAGE_TYPE_OPS(Unaccepted, unaccepted, unaccepted) FOLIO_TYPE_OPS(large_kmalloc, large_kmalloc) +/* + * 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); \ }) diff --git a/io_uring/zcrx.c b/io_uring/zcrx.c index e5ff49f3425e..4cceb97ca26a 100644 --- a/io_uring/zcrx.c +++ b/io_uring/zcrx.c @@ -444,6 +444,7 @@ static int io_zcrx_create_area(struct io_zcrx_ifq *ifq, area->freelist[i] = i; atomic_set(&area->user_refs[i], 0); niov->type = NET_IOV_IOURING; + niov->pp = NULL; } area->free_count = nr_iovs; diff --git a/mm/page_alloc.c b/mm/page_alloc.c index d1d037f97c5f..2f6a55fab942 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -1042,7 +1042,6 @@ static inline bool page_expected_state(struct page *page, #ifdef CONFIG_MEMCG page->memcg_data | #endif - page_pool_page_is_pp(page) | (page->flags & check_flags))) return false; @@ -1069,8 +1068,6 @@ static const char *page_bad_reason(struct page *page, unsigned long flags) if (unlikely(page->memcg_data)) bad_reason = "page still charged to cgroup"; #endif - if (unlikely(page_pool_page_is_pp(page))) - bad_reason = "page_pool leak"; return bad_reason; } @@ -1379,9 +1376,11 @@ __always_inline bool free_pages_prepare(struct page *page, mod_mthp_stat(order, MTHP_STAT_NR_ANON, -1); folio->mapping = NULL; } - if (unlikely(page_has_type(page))) + if (unlikely(page_has_type(page))) { + WARN_ON_ONCE(PageNetpp(page)); /* Reset the page_type (which overlays _mapcount) */ page->page_type = UINT_MAX; + } if (is_check_pages_enabled()) { if (free_page_is_bad(page)) diff --git a/net/core/devmem.c b/net/core/devmem.c index b3a62ca0df65..40e7a4ec9009 100644 --- a/net/core/devmem.c +++ b/net/core/devmem.c @@ -285,6 +285,7 @@ net_devmem_bind_dmabuf(struct net_device *dev, niov = &owner->area.niovs[i]; niov->type = NET_IOV_DMABUF; niov->owner = &owner->area; + niov->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 cd95394399b4..4b90332d6c64 100644 --- a/net/core/netmem_priv.h +++ b/net/core/netmem_priv.h @@ -8,21 +8,18 @@ static inline unsigned long netmem_get_pp_magic(netmem_ref netmem) return __netmem_clear_lsb(netmem)->pp_magic & ~PP_DMA_INDEX_MASK; } -static inline void netmem_or_pp_magic(netmem_ref netmem, unsigned long pp_magic) -{ - __netmem_clear_lsb(netmem)->pp_magic |= 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 = 0; -} - static inline bool netmem_is_pp(netmem_ref netmem) { - return (netmem_get_pp_magic(netmem) & PP_MAGIC_MASK) == PP_SIGNATURE; + /* Use ->pp for net_iov to identify if it's pp, which requires + * that non-pp net_iov should have ->pp NULL'd. + */ + if (netmem_is_net_iov(netmem)) + return !!__netmem_clear_lsb(netmem)->pp; + + /* For system memory, page type bit in struct page can be used + * to identify if it's pp. + */ + return PageNetpp(__netmem_to_page(netmem)); } 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, 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); /* 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, netmem_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)); } 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)); } static __always_inline void __page_pool_release_netmem_dma(struct page_pool *pool, base-commit: 0b90c3b6d76ea512dc3dac8fb30215e175b0019a -- 2.17.1