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Miller" , Jakub Kicinski , Jesper Dangaard Brouer , Saeed Mahameed , Leon Romanovsky , Tariq Toukan , Andrew Lunn , Eric Dumazet , Paolo Abeni , Ilias Apalodimas , Simon Horman , Andrew Morton , Mina Almasry , Yonglong Liu , Yunsheng Lin , Pavel Begunkov , Matthew Wilcox Cc: netdev@vger.kernel.org, bpf@vger.kernel.org, linux-rdma@vger.kernel.org, linux-mm@kvack.org Subject: Re: [PATCH net-next v7 1/2] page_pool: Move pp_magic check into helper functions In-Reply-To: References: <20250404-page-pool-track-dma-v7-0-ad34f069bc18@redhat.com> <20250404-page-pool-track-dma-v7-1-ad34f069bc18@redhat.com> X-Clacks-Overhead: GNU Terry Pratchett Date: Mon, 07 Apr 2025 10:53:55 +0200 Message-ID: <87cydoxsgs.fsf@toke.dk> Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable "Zi Yan" writes: > On Fri Apr 4, 2025 at 6:18 AM EDT, Toke H=C3=B8iland-J=C3=B8rgensen wrote: >> Since we are about to stash some more information into the pp_magic >> field, let's move the magic signature checks into a pair of helper >> functions so it can be changed in one place. >> >> Reviewed-by: Mina Almasry >> Tested-by: Yonglong Liu >> Acked-by: Jesper Dangaard Brouer >> Reviewed-by: Ilias Apalodimas >> Signed-off-by: Toke H=C3=B8iland-J=C3=B8rgensen >> --- >> drivers/net/ethernet/mellanox/mlx5/core/en/xdp.c | 4 ++-- >> include/net/page_pool/types.h | 18 ++++++++++++++++++ >> mm/page_alloc.c | 9 +++------ >> net/core/netmem_priv.h | 5 +++++ >> net/core/skbuff.c | 16 ++-------------- >> net/core/xdp.c | 4 ++-- >> 6 files changed, 32 insertions(+), 24 deletions(-) >> > > > >> diff --git a/include/net/page_pool/types.h b/include/net/page_pool/types= .h >> index 36eb57d73abc6cfc601e700ca08be20fb8281055..df0d3c1608929605224feb26= 173135ff37951ef8 100644 >> --- a/include/net/page_pool/types.h >> +++ b/include/net/page_pool/types.h >> @@ -54,6 +54,14 @@ struct pp_alloc_cache { >> netmem_ref cache[PP_ALLOC_CACHE_SIZE]; >> }; >>=20=20 >> +/* Mask used for checking in page_pool_page_is_pp() below. page->pp_mag= ic is >> + * OR'ed with PP_SIGNATURE after the allocation in order to preserve bi= t 0 for >> + * the head page of compound page and bit 1 for pfmemalloc page. >> + * page_is_pfmemalloc() is checked in __page_pool_put_page() to avoid r= ecycling >> + * the pfmemalloc page. >> + */ >> +#define PP_MAGIC_MASK ~0x3UL >> + >> /** >> * struct page_pool_params - page pool parameters >> * @fast: params accessed frequently on hotpath >> @@ -264,6 +272,11 @@ void page_pool_destroy(struct page_pool *pool); >> void page_pool_use_xdp_mem(struct page_pool *pool, void (*disconnect)(v= oid *), >> const struct xdp_mem_info *mem); >> void page_pool_put_netmem_bulk(netmem_ref *data, u32 count); >> + >> +static inline bool page_pool_page_is_pp(struct page *page) >> +{ >> + return (page->pp_magic & PP_MAGIC_MASK) =3D=3D PP_SIGNATURE; >> +} >> #else >> static inline void page_pool_destroy(struct page_pool *pool) >> { >> @@ -278,6 +291,11 @@ static inline void page_pool_use_xdp_mem(struct pag= e_pool *pool, >> static inline void page_pool_put_netmem_bulk(netmem_ref *data, u32 coun= t) >> { >> } >> + >> +static inline bool page_pool_page_is_pp(struct page *page) >> +{ >> + return false; >> +} >> #endif >>=20=20 >> void page_pool_put_unrefed_netmem(struct page_pool *pool, netmem_ref ne= tmem, >> diff --git a/mm/page_alloc.c b/mm/page_alloc.c >> index f51aa6051a99867d2d7d8c70aa7c30e523629951..347a3cc2c188f4a9ced85e0d= 198947be7c503526 100644 >> --- a/mm/page_alloc.c >> +++ b/mm/page_alloc.c >> @@ -55,6 +55,7 @@ >> #include >> #include >> #include >> +#include >> #include >> #include "internal.h" >> #include "shuffle.h" >> @@ -897,9 +898,7 @@ static inline bool page_expected_state(struct page *= page, >> #ifdef CONFIG_MEMCG >> page->memcg_data | >> #endif >> -#ifdef CONFIG_PAGE_POOL >> - ((page->pp_magic & ~0x3UL) =3D=3D PP_SIGNATURE) | >> -#endif >> + page_pool_page_is_pp(page) | >> (page->flags & check_flags))) >> return false; >>=20=20 >> @@ -926,10 +925,8 @@ static const char *page_bad_reason(struct page *pag= e, unsigned long flags) >> if (unlikely(page->memcg_data)) >> bad_reason =3D "page still charged to cgroup"; >> #endif >> -#ifdef CONFIG_PAGE_POOL >> - if (unlikely((page->pp_magic & ~0x3UL) =3D=3D PP_SIGNATURE)) >> + if (unlikely(page_pool_page_is_pp(page))) >> bad_reason =3D "page_pool leak"; >> -#endif >> return bad_reason; >> } >>=20=20 > > I wonder if it is OK to make page allocation depend on page_pool from > net/page_pool. Why? It's not really a dependency, just a header include with a static inline function... > Would linux/mm.h be a better place for page_pool_page_is_pp()? That would require moving all the definitions introduced in patch 2, which I don't think is appropriate. -Toke