Re: [PATCH linux-next v3] mm, page_pool: introduce a new page type for page pool in page type
From: Jakub Kicinski <kuba@kernel.org>
Date: 2025-08-01 23:08:08
Also in:
bpf, linux-mm, linux-rdma, lkml
On Tue, 29 Jul 2025 20:02:10 +0900 Byungchul Park wrote:
[PATCH linux-next v3] mm, page_pool: introduce a new page type for page pool in page type
linux-next does not accept patches. This has to go either via networking or MM.
- if (unlikely(page_has_type(page)))
+ if (unlikely(page_has_type(page))) {Maybe add : /* networking expects to clear its page type before releasing */
+ WARN_ON_ONCE(PageNetpp(page)); /* Reset the page_type (which overlays _mapcount) */ page->page_type = UINT_MAX; + }
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, Please try to use precise language, this code is confusing as is. net_iov may _belong_ to a page pool. * which requires that non-pp net_iov should have ->pp NULL'd. I don't think this adds any information.
+ */ + if (netmem_is_net_iov(netmem)) + return !!__netmem_clear_lsb(netmem)->pp; + + /* For system memory, page type bit in struct page can be used
"page type bit" -> "page type", it's not a bit.
+ * to identify if it's pp.
... to identify pages which belong to a page pool.
quoted hunk ↗ jump to hunk
+ */ + 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 */
Please don't add obvious comments.
+ if (!netmem_is_net_iov(netmem)) + __SetPageNetpp(__netmem_to_page(netmem));