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 775BD22D781; Mon, 21 Jul 2025 08:19:17 +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=1753085968; cv=none; b=mzhohovBqsmaheCbLFnjMPZMUw11iul1pA+hGwgH0aZEtsAMwT+E0+MOAwcqd2t+baNw0ENnkNrEjx17peG9k0eV+FIrPxpHijWqEMKI4jfYgVSWSOJ94zwSVs5wIoTKBuzm8n4IlzfXfJLSmX1XX7+smiD5Pg5zmLNhs+o8cE4= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1753085968; c=relaxed/simple; bh=3qogy6Eu124weeVZ0Zp2cNlMb4SiB0GBWDEiO6+5yyc=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=F2neEhN74Hkj23wc5MnM7fxhiEfgvuv/6uFwykQDSW4UqjaK0gczCFEC0wVlusePNSuD3O06BfW1l97491yOg50EowAWxX6g3dHQFtfNG2o29Tvr0WG0eUMd/ff63wyvI4kpXh+XX2ZgLZjjDFnmZSdcphg2elGqaX81IDFRIAw= 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-681ff7000002311f-91-687df80446e0 Date: Mon, 21 Jul 2025 17:19:10 +0900 From: Byungchul Park To: David Hildenbrand Cc: linux-mm@kvack.org, netdev@vger.kernel.org, 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, 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: Re: [PATCH] mm, page_pool: introduce a new page type for page pool in page type Message-ID: <20250721081910.GA21207@system.software.com> References: <20250721054903.39833-1-byungchul@sk.com> Precedence: bulk X-Mailing-List: bpf@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: User-Agent: Mutt/1.9.4 (2018-02-28) X-Brightmail-Tracker: H4sIAAAAAAAAA02Sf0zMcRjHfb6f732/327Ovs7hI3+w83O3Ob+yPQzT/OHjD783mx+TU1/d TZ3bpXSmOQpJHaPbdC4iP1JNXOkuU7jSDzZS005SVJhRqKSTxV0Y/732PM/79Tx/PAJWumWh gsG4RzIbdTFqTs7Ku0ZenMUOJOnnpH+eDs6iQg4KBhLh6iuPDJz5pQj6/C94+FlejaC3qoaD D5U9CHIv9GNwPklh4WvRdwxvqtt5KHCtgrYrb1m4c9SNof1ELQcZKYMYyv3dPBzy5DHgLLby UF9qk0Hm98sY3NZXPDTednLQWvhTBm+9GSzUOa6x8NlehaHNtgyqc8ZB/6OPCKqK3Az0p2dz 8CzrNgOnG3I46EhpQ9BQ2c6C/UcqB2cP2hAMDgRs3Sf7ZHD2QSu/TEMrP37CtOTac4b6Kh4y tMzxkqc5rnhanKehab4GTF35xzjq6jnF05amOxytPTPI0rLXC2mZp5ehGcndHP3yppmlnyqe cWvHbJYvjpJiDAmSefbS7XJ9XXYGNuWGJyb7e3kr+qZNQyECEcPI9XdD/F/uKqllgsyK04g9 6wkKMifOID6fHwdZJc4kriM3AiwXsOjkSYMtezg8RtxM6q3lw2GFCORMctpwQCkaiP30b5FC HE3qsjrZIGNRQ3xD7wPzQoAnkqtDQrAcIi4ll5psw5qx4hRyr7SGCe4iYotAOppv/jl0Armf 52NPItHxn9bxn9bxT5uDcD5SGowJsTpDTJhWbzEaErWRu2NdKPBOV5J+bPGgnvoNXiQKSD1S YWKT9EqZLiHOEutFRMBqlYLW7NMrFVE6yz7JvDvCHB8jxXnRRIFVj1fM698bpRSjdXukXZJk ksx/u4wQEmpFa1u3teU+tqw8tzp1vvv4iLQbByftUIV/9SRv3JuSvq7k/IUlHVst97WtLYYK 7YKoUWuKCxZVT9d2xkfLmn34aU2oSaUKj9AoPyxvaYw0Nhd22e5mPh3nP27aNPkAN7U99fn6 zMbSzseHo+1JW96rbkmj9+sjb15cUemNjSh7uWHn9j41G6fXzdVgc5zuFxYBtBZKAwAA X-Brightmail-Tracker: H4sIAAAAAAAAA02Sa0hTYRjHec97ds5xtDgtq1NK0SIqI7Po8pRdKeilKMIgQ4o85Kkt3ZSt RANhqd0s13WUa4a1vEvGvE1xUmrq6kM1L6yrZllkaqVmXqLajKhvP57///f/9HBYmSGbwWl0 RyS9ToxRMXJaviM0ZRE9nKQOcZbIwVpcxEDhcALkdjhkYC0oRzA48oKFX84GBAP1jQx8qutH YLs5hMH6OJWGb8WjGLoaOlkotG+H9pz3NFSfqsDQeb6JgfTUMQzOkT4Wkh15FFhLjCzUZbpk 8KTcJIMro9kYKowdLDRXWRl4XfRLBu9r02lwWfJp+GKux9Bu2gANWVNh6FEPgvriCgqGzmUy 0JpRRcFldxYDb1PbEbjrOmkw/zjNwPXjJgRjw961vguDMrj+4DW7YSGp6/mMSWn+M4p4ah5S pNLyiiVZ9qOkJC+IpHncmNgLzjDE3n+JJS/bqhnSdG2MJpVvVpFKxwBF0lP6GPK16zlNPte0 Mjv9I+RroqQYTbykX7wuUq52ZabjONvGhJSRAdaIvgenIT9O4JcJvaVNlI9pfq5gzniMfMzw 8wSPZwT72J+fL9hP3vWynMO8lRXcpkzWF0zmI4QnRue4rOBBuJaSNi4oeY1gvvxnSMFPElwZ 72gfYz5I8Pz86O1zXg4Qcn9yvrMfv0643WYan5nCzxHulTdSF5DC8p9t+c+2/LOzEC5A/hpd vFbUxCwPNkSrE3WahOADsVo78j5MTtKPiw402LylFvEcUk1QxNFJaqVMjDckamuRwGGVv4I0 HlMrFVFi4jFJH7tffzRGMtSiAI5WTVNsDZcilfwh8YgULUlxkv5vSnF+M4woMrAs0Nay9ur9 544Vro6nZw9GO6Xcw3sCWw5GrC7b1HKjOnS3raOgBk33Cw3JKzFv7+pa2Z08MeTjiakvV53b uytsVHc2eJI6oHx9s/zQ930LxJNNS79VvvswrE12o1kV1Y8+hIVjbUNbbz/S980u7p3j6t5s mXvrzsxtPVsviknZNhVtUItLgrDeIP4GDJeV7SwDAAA= X-CFilter-Loop: Reflected On Mon, Jul 21, 2025 at 10:05:25AM +0200, David Hildenbrand wrote: > On 21.07.25 07:49, Byungchul Park wrote: > > 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 > > > > ---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/ > > I'm, sure you saw my comment (including my earlier suggestion for using > a page type), in particular around ... Honestly, I was too confused to understand exactly what you meant. Maybe my bad but I was and I'm still so. Lemme add a question below. > > --- > > .../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 *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 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 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. > > * > > @@ -4168,25 +4167,4 @@ 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 > > - > > #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 = 0xf6, > > PGTY_unaccepted = 0xf7, > > PGTY_large_kmalloc = 0xf8, > > + PGTY_netpp = 0xf9, > > > > PGTY_mapcount_underflow = 0xff > > }; > > @@ -1101,6 +1102,11 @@ 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/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 *page, > > #ifdef CONFIG_MEMCG > > page->memcg_data | > > #endif > > - page_pool_page_is_pp(page) | > > + PageNetpp(page) | > > (page->flags & check_flags))) > > return false; > > > > @@ -925,7 +925,7 @@ 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))) > > + if (unlikely(PageNetpp(page))) > > bad_reason = "page_pool leak"; > > return bad_reason; > > } > > ^ this > > This will not work they way you want it once you rebase on top of > linux-next, where we have (from mm/mm-stable) > > commit 2dfcd1608f3a96364f10de7fcfe28727c0292e5d I just checked this. So is it sufficient that I rebase on mm/mm-stable? Or should I wait for something else? Or should I achieve this in other ways? Byungchul > Author: David Hildenbrand > Date: Fri Jul 4 12:24:58 2025 +0200 > > mm/page_alloc: let page freeing clear any set page type > > > I commented what to do already. > > -- > Cheers, > > David / dhildenb