From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from invmail4.hynix.com (exvmail4.skhynix.com [166.125.252.92]) by smtp.subspace.kernel.org (Postfix) with ESMTP id 79A522BF3C5; Wed, 13 Aug 2025 06:09:08 +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=1755065357; cv=none; b=kb/7JQcPFLmeU6/odzUqL2pac9gItdMOK+MIztQP6aC4nsoeuTmBWhieFtrHTP8BNce/wnP2KFnfBz5YzX/QRJ5WZu6I9/AYi6GK8RhnIR14sCtaGQnxVi6UXsdXzaiwAtRvEsFzFgOj0D3a7SETfLju02hDIrC9oiAO3REB7zk= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1755065357; c=relaxed/simple; bh=jAYCNPl3IH1M0tMX6iXobNNOeuD4g0C7OQB6gQ32e0Q=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=Pc0S2N9Zci+O6kFwowbez/WREOmkZBXooXEGXwLICcERMj2nReRSMfLQ74KuhXz9QEamdGi1CQYaeK00xoQVkikcfInb/dOxVq1TWcrOWxiWWaobUTgy8wHdrSXiUeTqsSnQyOtYf05bnA2gNvTsZMyL2P5TSuQLujQkb++eOLs= 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-c45ff70000001609-ca-689c2c035287 Date: Wed, 13 Aug 2025 15:09:01 +0900 From: Byungchul Park To: akpm@linux-foundation.org, kuba@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, 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, linux-mm@kvack.org, netdev@vger.kernel.org Subject: Re: [PATCH linux-next v3] mm, page_pool: introduce a new page type for page pool in page type Message-ID: <20250813060901.GA9086@system.software.com> References: <20250729110210.48313-1-byungchul@sk.com> Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20250729110210.48313-1-byungchul@sk.com> User-Agent: Mutt/1.9.4 (2018-02-28) X-Brightmail-Tracker: H4sIAAAAAAAAA02Sa0hTYRjHec85O+e4Wr0tq7ciyHURrNa9Hu1idIFDEhRBH5KylYc21Flb mUaXmUK18tLFyDltUpkuwZip0zLymhWUGcaxm7lSkGyVlnnD2jEiv/34P//nx/Ph4Wm1WzGN NxgPiSajLlrDKhnll7G5C+j5dv2il8MBYC8qZOF2Xzzc+uBWgN1ZiuBH/xsOflfWI+ipfcTC 55puBNdze2mwP09m4GfRAA3t9R4Obru2QGteBwP3T5fR4ElrYCEleZCGyn4vB6fc+RTYiy0c NJamKuDywE0ayiwfOHhZYWfhfeFvBXRUpzDw2FbAwLeMWhpaU9dBvWMy9D7tQlBbVEZB7/ls FpozKygoqWzm4FKTg4WPya0Immo8DGQMnWEhKzEVwWCfT+lN/6GArLr33Lp5QqIksUJN11da uFvQQgnSgyeUUG57xwkO12GhOD9IsEpNtOBynmUFV/dFTnj76j4rNFwdZITytmCh3N1DCSlJ Xlb43v6a2eq/U7k6Uow2xImmhWv3KPU38u6gA5m7452FwRZ0L8yK/HiClxFnXhFrRfwIX0uf LccMnkOe1X5nZGZxIJGkflpmf6wlXWlJI0zjAo4Mt42ReSLWk+Kcj5SsUeGV5GfJVDlW4+XE mfKJlVmFJ5DHmZ+Yv6tBRBruHKnTeDq5NczLsR9eQeoaqpDMk/As8rD0ka+i9B32lif1jhb0 9+KppCpfYtIRto3S2kZpbf+1DkQ7kdpgjIvRGaKXafUJRkO8dl9sjAv5/inv+FC4G3U3bq9G mEeasarGkCy9WqGLMyfEVCPC0xp/VfYuX6SK1CUcFU2xEabD0aK5Gk3nGc0U1ZLeI5FqvF93 SIwSxQOi6d+U4v2mWdCOyeGFgTkn17Tf00ScK/Zejor9Wrc30eD2tF7Ebelzs4w9Ueu95gvN 2s6kUE3VScWmxdaBYzkT9mpndJSZM5MWOENeXbmwtipm84ldOKSk03Aku+fZhiirZWlubNyi iPHUvI1cxbYMP9O5MCnHs8oprZkZWte5+uo4VcCv7Q9ePDmoYcx63eIg2mTW/QGB7RhvSwMA AA== X-Brightmail-Tracker: H4sIAAAAAAAAA02Sf0yMcRzHfZ/vc8/zdNz2SHho2E4WqbCJT2WVtfHIMn8xjLrpmbvVVbuj FWNRI81VfoSuS5mkrqhdqrsU6q6rMFKLkx/9UG1oqS5NP1a6zPTfa+/P+/X+68NgZ61oJaOI PimoomVRUkpMivf5J3lhT518c1mvGHSlJRQU/46HB11GEej0lQhGxz/SMFNrRWC3NFLwwzyC 4N7dMQy6N8kk/CqdwNBn7aGh2BAKnQX9JNRcqsLQk95EgSZ5EkPt+CANF4yFBOjKE2kw5zSL oKUyTQQ3Ju5jqErsoqGtWkfBl5IZEfTXa0ho1haRMJRpwdCZFgTWvGUw9nIAgaW0ioCxKzkU tGdVE1BR207D9dY8Cr4mdyJoNfeQkDmVQkH2+TQEk79nJwczRkWQ3fCFDvLkz9tsFG8e+In5 x0UfCN729AXBm7SfaT7PcIovL/TgU22tmDfoL1O8YeQazX96V0PxTbcnSd7U7cubjHaC1yQN UvxwXwe5f+lh8Y4IIUoRJ6g2BYSL5fkFZSg261i8vsQ3ET3Zm4oYhmO3crkZbqnIiSHZddxr yzDpYIp152y2cexgF9abG0hPmmPMFtHcdPdCBy9h5Vz5na+EY0bCbud+VaxwxM6sD6fX9FIO lrCLueasXvKv6sHZpr/N1THryj2YZhyxE7uNa2iqQw5eyq7lnlc2EhlIop1na+fZ2v92HsJ6 5KKIjlPKFFE+3upIeUK0It77eIzSgGY/puDs1FUjGm3bXY9YBkkXSVr8suXOIlmcOkFZjzgG S10kOUdnI0mELOG0oIoJU52KEtT1yJUhpcslIQeFcGf2hOykECkIsYLq35VgnFYmohulC+Rt O5UDp63B/sv88PdMp6FHu/aQ+dMG0iIbD6SsAR1hocPPQozgd98tP9B+80hfb92J92VVIXbG FHRuvc/CwIf+I1qRuvlQ/JlgblWwvSZLu7qtw8vSsjHmlnIiMmhNGcPeOmN29zHX5fq91aSZ Xl3s31D9fs+BMEiRb5KSarlsiwdWqWV/AEGc1q0tAwAA X-CFilter-Loop: Reflected On Tue, Jul 29, 2025 at 08:02:10PM +0900, Byungchul Park wrote: > Changes from v2: > 1. Rebase on linux-next as of Jul 29. > 2. Skip 'niov->pp = NULL' when it's allocated using __GFP_ZERO. > 3. Change trivial coding style. (feedbacked by Mina) > 4. Add Co-developed-by, Acked-by, and Reviewed-by properly. > Thanks to all. > > 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 88bcb9907a0cef65a9c0adf35e144f9eb67e0542 Mon Sep 17 00:00:00 2001 > From: Byungchul Park > Date: Tue, 29 Jul 2025 19:49:44 +0900 > Subject: [PATCH linux-next v3] 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. Hi, Andrew and Jakub I will spin the next one with some modified, once the following patch, [1], gets merged. [1] https://lore.kernel.org/all/a8643abedd208138d3d550db71631d5a2e4168d1.1754929026.git.asml.silence@gmail.com/ This is about both mm and network. I have no idea which tree should I aim at between mm tree and network tree? I prefer the network tree tho. However, it's totally fine regardless of what it would be. Suggestion? Byungchul > Suggested-by: David Hildenbrand > Co-developed-by: Pavel Begunkov > Signed-off-by: Pavel Begunkov > Signed-off-by: Byungchul Park > Acked-by: David Hildenbrand > Reviewed-by: Mina Almasry > --- > .../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 | 4 +++ > 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, 37 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..f771bb3e756d 100644 > --- a/io_uring/zcrx.c > +++ b/io_uring/zcrx.c > @@ -444,6 +444,10 @@ 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 is already initialized to NULL by > + * kvmalloc_array(__GFP_ZERO). > + */ > } > > 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..37eeab76c41c 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 it's page-backed */ > + if (!netmem_is_net_iov(netmem)) > + __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 it's page-backed */ > + if (!netmem_is_net_iov(netmem)) > + __ClearPageNetpp(__netmem_to_page(netmem)); > } > > static __always_inline void __page_pool_release_netmem_dma(struct page_pool *pool, > > base-commit: 54efec8782214652b331c50646013f8526570e8d > -- > 2.17.1