| Message ID | 20240305020153.2787423-9-almasrymina@google.com (mailing list archive) |
|---|---|
| State | RFC |
| Delegated to: | Netdev Maintainers |
| Headers | show |
| Series | Device Memory TCP | expand |
On Mon, Mar 4, 2024 at 6:02 PM Mina Almasry <almasrymina@google.com> wrote: > > Convert netmem to be a union of struct page and struct netmem. Overload > the LSB of struct netmem* to indicate that it's a net_iov, otherwise > it's a page. > > Currently these entries in struct page are rented by the page_pool and > used exclusively by the net stack: > > struct { > unsigned long pp_magic; > struct page_pool *pp; > unsigned long _pp_mapping_pad; > unsigned long dma_addr; > atomic_long_t pp_ref_count; > }; > > Mirror these (and only these) entries into struct net_iov and implement > netmem helpers that can access these common fields regardless of > whether the underlying type is page or net_iov. > > Implement checks for net_iov in netmem helpers which delegate to mm > APIs, to ensure net_iov are never passed to the mm stack. > > Signed-off-by: Mina Almasry <almasrymina@google.com> > Per David Howell's request, I'm forwarding these 2 patches from the series to linux-mm & Mathew Wilcox. https://lore.kernel.org/netdev/950858.1709622997@warthog.procyon.org.uk/ +linux-mm +Mathew Wilcox +David Howells Some background on how we arrived at the current design may be useful. This was largely discussed across 2 (long) email threads, largely with Jason Gunthorpe and Christian Konig: https://lore.kernel.org/lkml/CAHS8izPm6XRS54LdCDZVd0C75tA1zHSu6jLVO8nzTLXCc=H7Nw@mail.gmail.com/ https://lore.kernel.org/bpf/CAHS8izMdKYyjE9bdcFDWWPWECwVZL7XQjtjOFoTq5_bEEJvN6w@mail.gmail.com/ The approach is based on supporting dma-buf scatterlist entries in the networking stack, to support receiving data directly into GPU memory typically represented by dmabuf. I added the abstract netmem_ref type in a recent series that can multiplex between struct pages and non-struct pages (called net_iovs in this series): https://lore.kernel.org/netdev/20240214223405.1972973-1-almasrymina@google.com/ > --- > > v6: > - Rebased on top of the merged netmem_ref type. > - Rebased on top of the merged skb_pp_frag_ref() changes. > > v5: > - Use netmem instead of page* with LSB set. > - Use pp_ref_count for refcounting net_iov. > - Removed many of the custom checks for netmem. > > v1: > - Disable fragmentation support for iov properly. > - fix napi_pp_put_page() path (Yunsheng). > - Use pp_frag_count for devmem refcounting. > > --- > include/net/netmem.h | 142 ++++++++++++++++++++++++++++++-- > include/net/page_pool/helpers.h | 25 +++--- > include/net/page_pool/types.h | 1 + > net/core/page_pool.c | 26 +++--- > net/core/skbuff.c | 23 +++--- > 5 files changed, 171 insertions(+), 46 deletions(-) > > diff --git a/include/net/netmem.h b/include/net/netmem.h > index 21f53b29e5fe..8699788d587d 100644 > --- a/include/net/netmem.h > +++ b/include/net/netmem.h > @@ -9,14 +9,51 @@ > #define _NET_NETMEM_H > > #include <net/devmem.h> > +#include <net/net_debug.h> > > /* net_iov */ > > +DECLARE_STATIC_KEY_FALSE(page_pool_mem_providers); > + > +/* We overload the LSB of the struct page pointer to indicate whether it's > + * a page or net_iov. > + */ > +#define NET_IOV 0x01UL > + > struct net_iov { > + unsigned long __unused_padding; > + unsigned long pp_magic; > + struct page_pool *pp; > struct dmabuf_genpool_chunk_owner *owner; > unsigned long dma_addr; > + atomic_long_t pp_ref_count; > }; > > +/* These fields in struct page are used by the page_pool and net stack: > + * > + * struct { > + * unsigned long pp_magic; > + * struct page_pool *pp; > + * unsigned long _pp_mapping_pad; > + * unsigned long dma_addr; > + * atomic_long_t pp_ref_count; > + * }; > + * > + * We mirror the page_pool fields here so the page_pool can access these fields > + * without worrying whether the underlying fields belong to a page or net_iov. > + * > + * The non-net stack fields of struct page are private to the mm stack and must > + * never be mirrored to net_iov. > + */ > +#define NET_IOV_ASSERT_OFFSET(pg, iov) \ > + static_assert(offsetof(struct page, pg) == \ > + offsetof(struct net_iov, iov)) > +NET_IOV_ASSERT_OFFSET(pp_magic, pp_magic); > +NET_IOV_ASSERT_OFFSET(pp, pp); > +NET_IOV_ASSERT_OFFSET(dma_addr, dma_addr); > +NET_IOV_ASSERT_OFFSET(pp_ref_count, pp_ref_count); > +#undef NET_IOV_ASSERT_OFFSET > + > static inline struct dmabuf_genpool_chunk_owner * > net_iov_owner(const struct net_iov *niov) > { > @@ -69,20 +106,27 @@ net_iov_binding(const struct net_iov *niov) > */ > typedef unsigned long __bitwise netmem_ref; > > +static inline bool netmem_is_net_iov(const netmem_ref netmem) > +{ > +#ifdef CONFIG_PAGE_POOL > + return static_branch_unlikely(&page_pool_mem_providers) && > + (__force unsigned long)netmem & NET_IOV; > +#else > + return false; > +#endif > +} > + > /* This conversion fails (returns NULL) if the netmem_ref is not struct page > * backed. > - * > - * Currently struct page is the only possible netmem, and this helper never > - * fails. > */ > static inline struct page *netmem_to_page(netmem_ref netmem) > { > + if (WARN_ON_ONCE(netmem_is_net_iov(netmem))) > + return NULL; > + > return (__force struct page *)netmem; > } > > -/* Converting from page to netmem is always safe, because a page can always be > - * a netmem. > - */ > static inline netmem_ref page_to_netmem(struct page *page) > { > return (__force netmem_ref)page; > @@ -90,17 +134,103 @@ static inline netmem_ref page_to_netmem(struct page *page) > > static inline int netmem_ref_count(netmem_ref netmem) > { > + /* The non-pp refcount of net_iov is always 1. On net_iov, we only > + * support pp refcounting which uses the pp_ref_count field. > + */ > + if (netmem_is_net_iov(netmem)) > + return 1; > + > return page_ref_count(netmem_to_page(netmem)); > } > > static inline unsigned long netmem_to_pfn(netmem_ref netmem) > { > + if (netmem_is_net_iov(netmem)) > + return 0; > + > return page_to_pfn(netmem_to_page(netmem)); > } > > +static inline struct net_iov *__netmem_clear_lsb(netmem_ref netmem) > +{ > + return (struct net_iov *)((__force unsigned long)netmem & ~NET_IOV); > +} > + > +static inline unsigned long netmem_get_pp_magic(netmem_ref netmem) > +{ > + return __netmem_clear_lsb(netmem)->pp_magic; > +} > + > +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) > +{ > + __netmem_clear_lsb(netmem)->pp_magic = 0; > +} > + > +static inline struct page_pool *netmem_get_pp(netmem_ref netmem) > +{ > + return __netmem_clear_lsb(netmem)->pp; > +} > + > +static inline void netmem_set_pp(netmem_ref netmem, struct page_pool *pool) > +{ > + __netmem_clear_lsb(netmem)->pp = pool; > +} > + > +static inline unsigned long netmem_get_dma_addr(netmem_ref netmem) > +{ > + return __netmem_clear_lsb(netmem)->dma_addr; > +} > + > +static inline void netmem_set_dma_addr(netmem_ref netmem, > + unsigned long dma_addr) > +{ > + __netmem_clear_lsb(netmem)->dma_addr = dma_addr; > +} > + > +static inline atomic_long_t *netmem_get_pp_ref_count_ref(netmem_ref netmem) > +{ > + return &__netmem_clear_lsb(netmem)->pp_ref_count; > +} > + > +static inline bool netmem_is_pref_nid(netmem_ref netmem, int pref_nid) > +{ > + /* Assume net_iov are on the preferred node without actually > + * checking... > + * > + * This check is only used to check for recycling memory in the page > + * pool's fast paths. Currently the only implementation of net_iov > + * is dmabuf device memory. It's a deliberate decision by the user to > + * bind a certain dmabuf to a certain netdev, and the netdev rx queue > + * would not be able to reallocate memory from another dmabuf that > + * exists on the preferred node, so, this check doesn't make much sense > + * in this case. Assume all net_iovs can be recycled for now. > + */ > + if (netmem_is_net_iov(netmem)) > + return true; > + > + return page_to_nid(netmem_to_page(netmem)) == pref_nid; > +} > + > static inline netmem_ref netmem_compound_head(netmem_ref netmem) > { > + /* niov are never compounded */ > + if (netmem_is_net_iov(netmem)) > + return netmem; > + > return page_to_netmem(compound_head(netmem_to_page(netmem))); > } > > +static inline void *netmem_address(netmem_ref netmem) > +{ > + if (netmem_is_net_iov(netmem)) > + return NULL; > + > + return page_address(netmem_to_page(netmem)); > +} > + > #endif /* _NET_NETMEM_H */ > diff --git a/include/net/page_pool/helpers.h b/include/net/page_pool/helpers.h > index 61814f91a458..c6a55eddefae 100644 > --- a/include/net/page_pool/helpers.h > +++ b/include/net/page_pool/helpers.h > @@ -215,7 +215,7 @@ inline enum dma_data_direction page_pool_get_dma_dir(struct page_pool *pool) > > static inline void page_pool_fragment_netmem(netmem_ref netmem, long nr) > { > - atomic_long_set(&netmem_to_page(netmem)->pp_ref_count, nr); > + atomic_long_set(netmem_get_pp_ref_count_ref(netmem), nr); > } > > /** > @@ -243,7 +243,7 @@ static inline void page_pool_fragment_page(struct page *page, long nr) > > static inline long page_pool_unref_netmem(netmem_ref netmem, long nr) > { > - struct page *page = netmem_to_page(netmem); > + atomic_long_t *pp_ref_count = netmem_get_pp_ref_count_ref(netmem); > long ret; > > /* If nr == pp_ref_count then we have cleared all remaining > @@ -260,19 +260,19 @@ static inline long page_pool_unref_netmem(netmem_ref netmem, long nr) > * initially, and only overwrite it when the page is partitioned into > * more than one piece. > */ > - if (atomic_long_read(&page->pp_ref_count) == nr) { > + if (atomic_long_read(pp_ref_count) == nr) { > /* As we have ensured nr is always one for constant case using > * the BUILD_BUG_ON(), only need to handle the non-constant case > * here for pp_ref_count draining, which is a rare case. > */ > BUILD_BUG_ON(__builtin_constant_p(nr) && nr != 1); > if (!__builtin_constant_p(nr)) > - atomic_long_set(&page->pp_ref_count, 1); > + atomic_long_set(pp_ref_count, 1); > > return 0; > } > > - ret = atomic_long_sub_return(nr, &page->pp_ref_count); > + ret = atomic_long_sub_return(nr, pp_ref_count); > WARN_ON(ret < 0); > > /* We are the last user here too, reset pp_ref_count back to 1 to > @@ -281,7 +281,7 @@ static inline long page_pool_unref_netmem(netmem_ref netmem, long nr) > * page_pool_unref_page() currently. > */ > if (unlikely(!ret)) > - atomic_long_set(&page->pp_ref_count, 1); > + atomic_long_set(pp_ref_count, 1); > > return ret; > } > @@ -400,9 +400,7 @@ static inline void page_pool_free_va(struct page_pool *pool, void *va, > > static inline dma_addr_t page_pool_get_dma_addr_netmem(netmem_ref netmem) > { > - struct page *page = netmem_to_page(netmem); > - > - dma_addr_t ret = page->dma_addr; > + dma_addr_t ret = netmem_get_dma_addr(netmem); > > if (PAGE_POOL_32BIT_ARCH_WITH_64BIT_DMA) > ret <<= PAGE_SHIFT; > @@ -425,18 +423,17 @@ static inline dma_addr_t page_pool_get_dma_addr(struct page *page) > static inline bool page_pool_set_dma_addr_netmem(netmem_ref netmem, > dma_addr_t addr) > { > - struct page *page = netmem_to_page(netmem); > - > if (PAGE_POOL_32BIT_ARCH_WITH_64BIT_DMA) { > - page->dma_addr = addr >> PAGE_SHIFT; > + netmem_set_dma_addr(netmem, addr >> PAGE_SHIFT); > > /* We assume page alignment to shave off bottom bits, > * if this "compression" doesn't work we need to drop. > */ > - return addr != (dma_addr_t)page->dma_addr << PAGE_SHIFT; > + return addr != (dma_addr_t)netmem_get_dma_addr(netmem) > + << PAGE_SHIFT; > } > > - page->dma_addr = addr; > + netmem_set_dma_addr(netmem, addr); > return false; > } > > diff --git a/include/net/page_pool/types.h b/include/net/page_pool/types.h > index 68a24c5ae827..e29e77f7934e 100644 > --- a/include/net/page_pool/types.h > +++ b/include/net/page_pool/types.h > @@ -6,6 +6,7 @@ > #include <linux/dma-direction.h> > #include <linux/ptr_ring.h> > #include <linux/types.h> > +#include <net/netmem.h> > > #define PP_FLAG_DMA_MAP BIT(0) /* Should page_pool do the DMA > * map/unmap > diff --git a/net/core/page_pool.c b/net/core/page_pool.c > index 24d5236b2efc..22e3d439da18 100644 > --- a/net/core/page_pool.c > +++ b/net/core/page_pool.c > @@ -25,7 +25,7 @@ > > #include "page_pool_priv.h" > > -static DEFINE_STATIC_KEY_FALSE(page_pool_mem_providers); > +DEFINE_STATIC_KEY_FALSE(page_pool_mem_providers); > > #define DEFER_TIME (msecs_to_jiffies(1000)) > #define DEFER_WARN_INTERVAL (60 * HZ) > @@ -359,7 +359,7 @@ static noinline netmem_ref page_pool_refill_alloc_cache(struct page_pool *pool) > if (unlikely(!netmem)) > break; > > - if (likely(page_to_nid(netmem_to_page(netmem)) == pref_nid)) { > + if (likely(netmem_is_pref_nid(netmem, pref_nid))) { > pool->alloc.cache[pool->alloc.count++] = netmem; > } else { > /* NUMA mismatch; > @@ -446,10 +446,8 @@ static bool page_pool_dma_map(struct page_pool *pool, netmem_ref netmem) > > static void page_pool_set_pp_info(struct page_pool *pool, netmem_ref netmem) > { > - struct page *page = netmem_to_page(netmem); > - > - page->pp = pool; > - page->pp_magic |= PP_SIGNATURE; > + 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 > @@ -464,10 +462,8 @@ static void page_pool_set_pp_info(struct page_pool *pool, netmem_ref netmem) > > static void page_pool_clear_pp_info(netmem_ref netmem) > { > - struct page *page = netmem_to_page(netmem); > - > - page->pp_magic = 0; > - page->pp = NULL; > + netmem_clear_pp_magic(netmem); > + netmem_set_pp(netmem, NULL); > } > > static struct page *__page_pool_alloc_page_order(struct page_pool *pool, > @@ -695,8 +691,9 @@ static bool page_pool_recycle_in_cache(netmem_ref netmem, > > static bool __page_pool_page_can_be_recycled(netmem_ref netmem) > { > - return page_ref_count(netmem_to_page(netmem)) == 1 && > - !page_is_pfmemalloc(netmem_to_page(netmem)); > + return netmem_is_net_iov(netmem) || > + (page_ref_count(netmem_to_page(netmem)) == 1 && > + !page_is_pfmemalloc(netmem_to_page(netmem))); > } > > /* If the page refcnt == 1, this will try to recycle the page. > @@ -718,7 +715,7 @@ __page_pool_put_page(struct page_pool *pool, netmem_ref netmem, > * refcnt == 1 means page_pool owns page, and can recycle it. > * > * page is NOT reusable when allocated when system is under > - * some pressure. (page_is_pfmemalloc) > + * some pressure. (page_pool_page_is_pfmemalloc) > */ > if (likely(__page_pool_page_can_be_recycled(netmem))) { > /* Read barrier done in page_ref_count / READ_ONCE */ > @@ -734,6 +731,7 @@ __page_pool_put_page(struct page_pool *pool, netmem_ref netmem, > /* Page found as candidate for recycling */ > return netmem; > } > + > /* Fallback/non-XDP mode: API user have elevated refcnt. > * > * Many drivers split up the page into fragments, and some > @@ -928,7 +926,7 @@ static void page_pool_empty_ring(struct page_pool *pool) > /* Empty recycle ring */ > while ((netmem = (__force netmem_ref)ptr_ring_consume_bh(&pool->ring))) { > /* Verify the refcnt invariant of cached pages */ > - if (!(page_ref_count(netmem_to_page(netmem)) == 1)) > + if (!(netmem_ref_count(netmem) == 1)) > pr_crit("%s() page_pool refcnt %d violation\n", > __func__, netmem_ref_count(netmem)); > > diff --git a/net/core/skbuff.c b/net/core/skbuff.c > index e1118b637085..cf23392e97f5 100644 > --- a/net/core/skbuff.c > +++ b/net/core/skbuff.c > @@ -908,9 +908,9 @@ static void skb_clone_fraglist(struct sk_buff *skb) > skb_get(list); > } > > -static bool is_pp_page(struct page *page) > +static bool is_pp_netmem(netmem_ref netmem) > { > - return (page->pp_magic & ~0x3UL) == PP_SIGNATURE; > + return (netmem_get_pp_magic(netmem) & ~0x3UL) == PP_SIGNATURE; > } > > int skb_pp_cow_data(struct page_pool *pool, struct sk_buff **pskb, > @@ -1008,11 +1008,10 @@ EXPORT_SYMBOL(skb_cow_data_for_xdp); > #if IS_ENABLED(CONFIG_PAGE_POOL) > bool napi_pp_put_page(netmem_ref netmem, bool napi_safe) > { > - struct page *page = netmem_to_page(netmem); > bool allow_direct = false; > struct page_pool *pp; > > - page = compound_head(page); > + netmem = netmem_compound_head(netmem); > > /* page->pp_magic is OR'ed with PP_SIGNATURE after the allocation > * in order to preserve any existing bits, such as bit 0 for the > @@ -1021,10 +1020,10 @@ bool napi_pp_put_page(netmem_ref netmem, bool napi_safe) > * and page_is_pfmemalloc() is checked in __page_pool_put_page() > * to avoid recycling the pfmemalloc page. > */ > - if (unlikely(!is_pp_page(page))) > + if (unlikely(!is_pp_netmem(netmem))) > return false; > > - pp = page->pp; > + pp = netmem_get_pp(netmem); > > /* Allow direct recycle if we have reasons to believe that we are > * in the same context as the consumer would run, so there's > @@ -1045,7 +1044,7 @@ bool napi_pp_put_page(netmem_ref netmem, bool napi_safe) > * The page will be returned to the pool here regardless of the > * 'flipped' fragment being in use or not. > */ > - page_pool_put_full_netmem(pp, page_to_netmem(page), allow_direct); > + page_pool_put_full_netmem(pp, netmem, allow_direct); > > return true; > } > @@ -1072,7 +1071,7 @@ static bool skb_pp_recycle(struct sk_buff *skb, void *data, bool napi_safe) > static int skb_pp_frag_ref(struct sk_buff *skb) > { > struct skb_shared_info *shinfo; > - struct page *head_page; > + netmem_ref head_netmem; > int i; > > if (!skb->pp_recycle) > @@ -1081,11 +1080,11 @@ static int skb_pp_frag_ref(struct sk_buff *skb) > shinfo = skb_shinfo(skb); > > for (i = 0; i < shinfo->nr_frags; i++) { > - head_page = compound_head(skb_frag_page(&shinfo->frags[i])); > - if (likely(is_pp_page(head_page))) > - page_pool_ref_page(head_page); > + head_netmem = netmem_compound_head(shinfo->frags[i].netmem); > + if (likely(is_pp_netmem(head_netmem))) > + page_pool_ref_netmem(head_netmem); > else > - page_ref_inc(head_page); > + page_ref_inc(netmem_to_page(head_netmem)); > } > return 0; > } > -- > 2.44.0.rc1.240.g4c46232300-goog >
diff --git a/include/net/netmem.h b/include/net/netmem.h index 21f53b29e5fe..8699788d587d 100644 --- a/include/net/netmem.h +++ b/include/net/netmem.h @@ -9,14 +9,51 @@ #define _NET_NETMEM_H #include <net/devmem.h> +#include <net/net_debug.h> /* net_iov */ +DECLARE_STATIC_KEY_FALSE(page_pool_mem_providers); + +/* We overload the LSB of the struct page pointer to indicate whether it's + * a page or net_iov. + */ +#define NET_IOV 0x01UL + struct net_iov { + unsigned long __unused_padding; + unsigned long pp_magic; + struct page_pool *pp; struct dmabuf_genpool_chunk_owner *owner; unsigned long dma_addr; + atomic_long_t pp_ref_count; }; +/* These fields in struct page are used by the page_pool and net stack: + * + * struct { + * unsigned long pp_magic; + * struct page_pool *pp; + * unsigned long _pp_mapping_pad; + * unsigned long dma_addr; + * atomic_long_t pp_ref_count; + * }; + * + * We mirror the page_pool fields here so the page_pool can access these fields + * without worrying whether the underlying fields belong to a page or net_iov. + * + * The non-net stack fields of struct page are private to the mm stack and must + * never be mirrored to net_iov. + */ +#define NET_IOV_ASSERT_OFFSET(pg, iov) \ + static_assert(offsetof(struct page, pg) == \ + offsetof(struct net_iov, iov)) +NET_IOV_ASSERT_OFFSET(pp_magic, pp_magic); +NET_IOV_ASSERT_OFFSET(pp, pp); +NET_IOV_ASSERT_OFFSET(dma_addr, dma_addr); +NET_IOV_ASSERT_OFFSET(pp_ref_count, pp_ref_count); +#undef NET_IOV_ASSERT_OFFSET + static inline struct dmabuf_genpool_chunk_owner * net_iov_owner(const struct net_iov *niov) { @@ -69,20 +106,27 @@ net_iov_binding(const struct net_iov *niov) */ typedef unsigned long __bitwise netmem_ref; +static inline bool netmem_is_net_iov(const netmem_ref netmem) +{ +#ifdef CONFIG_PAGE_POOL + return static_branch_unlikely(&page_pool_mem_providers) && + (__force unsigned long)netmem & NET_IOV; +#else + return false; +#endif +} + /* This conversion fails (returns NULL) if the netmem_ref is not struct page * backed. - * - * Currently struct page is the only possible netmem, and this helper never - * fails. */ static inline struct page *netmem_to_page(netmem_ref netmem) { + if (WARN_ON_ONCE(netmem_is_net_iov(netmem))) + return NULL; + return (__force struct page *)netmem; } -/* Converting from page to netmem is always safe, because a page can always be - * a netmem. - */ static inline netmem_ref page_to_netmem(struct page *page) { return (__force netmem_ref)page; @@ -90,17 +134,103 @@ static inline netmem_ref page_to_netmem(struct page *page) static inline int netmem_ref_count(netmem_ref netmem) { + /* The non-pp refcount of net_iov is always 1. On net_iov, we only + * support pp refcounting which uses the pp_ref_count field. + */ + if (netmem_is_net_iov(netmem)) + return 1; + return page_ref_count(netmem_to_page(netmem)); } static inline unsigned long netmem_to_pfn(netmem_ref netmem) { + if (netmem_is_net_iov(netmem)) + return 0; + return page_to_pfn(netmem_to_page(netmem)); } +static inline struct net_iov *__netmem_clear_lsb(netmem_ref netmem) +{ + return (struct net_iov *)((__force unsigned long)netmem & ~NET_IOV); +} + +static inline unsigned long netmem_get_pp_magic(netmem_ref netmem) +{ + return __netmem_clear_lsb(netmem)->pp_magic; +} + +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) +{ + __netmem_clear_lsb(netmem)->pp_magic = 0; +} + +static inline struct page_pool *netmem_get_pp(netmem_ref netmem) +{ + return __netmem_clear_lsb(netmem)->pp; +} + +static inline void netmem_set_pp(netmem_ref netmem, struct page_pool *pool) +{ + __netmem_clear_lsb(netmem)->pp = pool; +} + +static inline unsigned long netmem_get_dma_addr(netmem_ref netmem) +{ + return __netmem_clear_lsb(netmem)->dma_addr; +} + +static inline void netmem_set_dma_addr(netmem_ref netmem, + unsigned long dma_addr) +{ + __netmem_clear_lsb(netmem)->dma_addr = dma_addr; +} + +static inline atomic_long_t *netmem_get_pp_ref_count_ref(netmem_ref netmem) +{ + return &__netmem_clear_lsb(netmem)->pp_ref_count; +} + +static inline bool netmem_is_pref_nid(netmem_ref netmem, int pref_nid) +{ + /* Assume net_iov are on the preferred node without actually + * checking... + * + * This check is only used to check for recycling memory in the page + * pool's fast paths. Currently the only implementation of net_iov + * is dmabuf device memory. It's a deliberate decision by the user to + * bind a certain dmabuf to a certain netdev, and the netdev rx queue + * would not be able to reallocate memory from another dmabuf that + * exists on the preferred node, so, this check doesn't make much sense + * in this case. Assume all net_iovs can be recycled for now. + */ + if (netmem_is_net_iov(netmem)) + return true; + + return page_to_nid(netmem_to_page(netmem)) == pref_nid; +} + static inline netmem_ref netmem_compound_head(netmem_ref netmem) { + /* niov are never compounded */ + if (netmem_is_net_iov(netmem)) + return netmem; + return page_to_netmem(compound_head(netmem_to_page(netmem))); } +static inline void *netmem_address(netmem_ref netmem) +{ + if (netmem_is_net_iov(netmem)) + return NULL; + + return page_address(netmem_to_page(netmem)); +} + #endif /* _NET_NETMEM_H */ diff --git a/include/net/page_pool/helpers.h b/include/net/page_pool/helpers.h index 61814f91a458..c6a55eddefae 100644 --- a/include/net/page_pool/helpers.h +++ b/include/net/page_pool/helpers.h @@ -215,7 +215,7 @@ inline enum dma_data_direction page_pool_get_dma_dir(struct page_pool *pool) static inline void page_pool_fragment_netmem(netmem_ref netmem, long nr) { - atomic_long_set(&netmem_to_page(netmem)->pp_ref_count, nr); + atomic_long_set(netmem_get_pp_ref_count_ref(netmem), nr); } /** @@ -243,7 +243,7 @@ static inline void page_pool_fragment_page(struct page *page, long nr) static inline long page_pool_unref_netmem(netmem_ref netmem, long nr) { - struct page *page = netmem_to_page(netmem); + atomic_long_t *pp_ref_count = netmem_get_pp_ref_count_ref(netmem); long ret; /* If nr == pp_ref_count then we have cleared all remaining @@ -260,19 +260,19 @@ static inline long page_pool_unref_netmem(netmem_ref netmem, long nr) * initially, and only overwrite it when the page is partitioned into * more than one piece. */ - if (atomic_long_read(&page->pp_ref_count) == nr) { + if (atomic_long_read(pp_ref_count) == nr) { /* As we have ensured nr is always one for constant case using * the BUILD_BUG_ON(), only need to handle the non-constant case * here for pp_ref_count draining, which is a rare case. */ BUILD_BUG_ON(__builtin_constant_p(nr) && nr != 1); if (!__builtin_constant_p(nr)) - atomic_long_set(&page->pp_ref_count, 1); + atomic_long_set(pp_ref_count, 1); return 0; } - ret = atomic_long_sub_return(nr, &page->pp_ref_count); + ret = atomic_long_sub_return(nr, pp_ref_count); WARN_ON(ret < 0); /* We are the last user here too, reset pp_ref_count back to 1 to @@ -281,7 +281,7 @@ static inline long page_pool_unref_netmem(netmem_ref netmem, long nr) * page_pool_unref_page() currently. */ if (unlikely(!ret)) - atomic_long_set(&page->pp_ref_count, 1); + atomic_long_set(pp_ref_count, 1); return ret; } @@ -400,9 +400,7 @@ static inline void page_pool_free_va(struct page_pool *pool, void *va, static inline dma_addr_t page_pool_get_dma_addr_netmem(netmem_ref netmem) { - struct page *page = netmem_to_page(netmem); - - dma_addr_t ret = page->dma_addr; + dma_addr_t ret = netmem_get_dma_addr(netmem); if (PAGE_POOL_32BIT_ARCH_WITH_64BIT_DMA) ret <<= PAGE_SHIFT; @@ -425,18 +423,17 @@ static inline dma_addr_t page_pool_get_dma_addr(struct page *page) static inline bool page_pool_set_dma_addr_netmem(netmem_ref netmem, dma_addr_t addr) { - struct page *page = netmem_to_page(netmem); - if (PAGE_POOL_32BIT_ARCH_WITH_64BIT_DMA) { - page->dma_addr = addr >> PAGE_SHIFT; + netmem_set_dma_addr(netmem, addr >> PAGE_SHIFT); /* We assume page alignment to shave off bottom bits, * if this "compression" doesn't work we need to drop. */ - return addr != (dma_addr_t)page->dma_addr << PAGE_SHIFT; + return addr != (dma_addr_t)netmem_get_dma_addr(netmem) + << PAGE_SHIFT; } - page->dma_addr = addr; + netmem_set_dma_addr(netmem, addr); return false; } diff --git a/include/net/page_pool/types.h b/include/net/page_pool/types.h index 68a24c5ae827..e29e77f7934e 100644 --- a/include/net/page_pool/types.h +++ b/include/net/page_pool/types.h @@ -6,6 +6,7 @@ #include <linux/dma-direction.h> #include <linux/ptr_ring.h> #include <linux/types.h> +#include <net/netmem.h> #define PP_FLAG_DMA_MAP BIT(0) /* Should page_pool do the DMA * map/unmap diff --git a/net/core/page_pool.c b/net/core/page_pool.c index 24d5236b2efc..22e3d439da18 100644 --- a/net/core/page_pool.c +++ b/net/core/page_pool.c @@ -25,7 +25,7 @@ #include "page_pool_priv.h" -static DEFINE_STATIC_KEY_FALSE(page_pool_mem_providers); +DEFINE_STATIC_KEY_FALSE(page_pool_mem_providers); #define DEFER_TIME (msecs_to_jiffies(1000)) #define DEFER_WARN_INTERVAL (60 * HZ) @@ -359,7 +359,7 @@ static noinline netmem_ref page_pool_refill_alloc_cache(struct page_pool *pool) if (unlikely(!netmem)) break; - if (likely(page_to_nid(netmem_to_page(netmem)) == pref_nid)) { + if (likely(netmem_is_pref_nid(netmem, pref_nid))) { pool->alloc.cache[pool->alloc.count++] = netmem; } else { /* NUMA mismatch; @@ -446,10 +446,8 @@ static bool page_pool_dma_map(struct page_pool *pool, netmem_ref netmem) static void page_pool_set_pp_info(struct page_pool *pool, netmem_ref netmem) { - struct page *page = netmem_to_page(netmem); - - page->pp = pool; - page->pp_magic |= PP_SIGNATURE; + 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 @@ -464,10 +462,8 @@ static void page_pool_set_pp_info(struct page_pool *pool, netmem_ref netmem) static void page_pool_clear_pp_info(netmem_ref netmem) { - struct page *page = netmem_to_page(netmem); - - page->pp_magic = 0; - page->pp = NULL; + netmem_clear_pp_magic(netmem); + netmem_set_pp(netmem, NULL); } static struct page *__page_pool_alloc_page_order(struct page_pool *pool, @@ -695,8 +691,9 @@ static bool page_pool_recycle_in_cache(netmem_ref netmem, static bool __page_pool_page_can_be_recycled(netmem_ref netmem) { - return page_ref_count(netmem_to_page(netmem)) == 1 && - !page_is_pfmemalloc(netmem_to_page(netmem)); + return netmem_is_net_iov(netmem) || + (page_ref_count(netmem_to_page(netmem)) == 1 && + !page_is_pfmemalloc(netmem_to_page(netmem))); } /* If the page refcnt == 1, this will try to recycle the page. @@ -718,7 +715,7 @@ __page_pool_put_page(struct page_pool *pool, netmem_ref netmem, * refcnt == 1 means page_pool owns page, and can recycle it. * * page is NOT reusable when allocated when system is under - * some pressure. (page_is_pfmemalloc) + * some pressure. (page_pool_page_is_pfmemalloc) */ if (likely(__page_pool_page_can_be_recycled(netmem))) { /* Read barrier done in page_ref_count / READ_ONCE */ @@ -734,6 +731,7 @@ __page_pool_put_page(struct page_pool *pool, netmem_ref netmem, /* Page found as candidate for recycling */ return netmem; } + /* Fallback/non-XDP mode: API user have elevated refcnt. * * Many drivers split up the page into fragments, and some @@ -928,7 +926,7 @@ static void page_pool_empty_ring(struct page_pool *pool) /* Empty recycle ring */ while ((netmem = (__force netmem_ref)ptr_ring_consume_bh(&pool->ring))) { /* Verify the refcnt invariant of cached pages */ - if (!(page_ref_count(netmem_to_page(netmem)) == 1)) + if (!(netmem_ref_count(netmem) == 1)) pr_crit("%s() page_pool refcnt %d violation\n", __func__, netmem_ref_count(netmem)); diff --git a/net/core/skbuff.c b/net/core/skbuff.c index e1118b637085..cf23392e97f5 100644 --- a/net/core/skbuff.c +++ b/net/core/skbuff.c @@ -908,9 +908,9 @@ static void skb_clone_fraglist(struct sk_buff *skb) skb_get(list); } -static bool is_pp_page(struct page *page) +static bool is_pp_netmem(netmem_ref netmem) { - return (page->pp_magic & ~0x3UL) == PP_SIGNATURE; + return (netmem_get_pp_magic(netmem) & ~0x3UL) == PP_SIGNATURE; } int skb_pp_cow_data(struct page_pool *pool, struct sk_buff **pskb, @@ -1008,11 +1008,10 @@ EXPORT_SYMBOL(skb_cow_data_for_xdp); #if IS_ENABLED(CONFIG_PAGE_POOL) bool napi_pp_put_page(netmem_ref netmem, bool napi_safe) { - struct page *page = netmem_to_page(netmem); bool allow_direct = false; struct page_pool *pp; - page = compound_head(page); + netmem = netmem_compound_head(netmem); /* page->pp_magic is OR'ed with PP_SIGNATURE after the allocation * in order to preserve any existing bits, such as bit 0 for the @@ -1021,10 +1020,10 @@ bool napi_pp_put_page(netmem_ref netmem, bool napi_safe) * and page_is_pfmemalloc() is checked in __page_pool_put_page() * to avoid recycling the pfmemalloc page. */ - if (unlikely(!is_pp_page(page))) + if (unlikely(!is_pp_netmem(netmem))) return false; - pp = page->pp; + pp = netmem_get_pp(netmem); /* Allow direct recycle if we have reasons to believe that we are * in the same context as the consumer would run, so there's @@ -1045,7 +1044,7 @@ bool napi_pp_put_page(netmem_ref netmem, bool napi_safe) * The page will be returned to the pool here regardless of the * 'flipped' fragment being in use or not. */ - page_pool_put_full_netmem(pp, page_to_netmem(page), allow_direct); + page_pool_put_full_netmem(pp, netmem, allow_direct); return true; } @@ -1072,7 +1071,7 @@ static bool skb_pp_recycle(struct sk_buff *skb, void *data, bool napi_safe) static int skb_pp_frag_ref(struct sk_buff *skb) { struct skb_shared_info *shinfo; - struct page *head_page; + netmem_ref head_netmem; int i; if (!skb->pp_recycle) @@ -1081,11 +1080,11 @@ static int skb_pp_frag_ref(struct sk_buff *skb) shinfo = skb_shinfo(skb); for (i = 0; i < shinfo->nr_frags; i++) { - head_page = compound_head(skb_frag_page(&shinfo->frags[i])); - if (likely(is_pp_page(head_page))) - page_pool_ref_page(head_page); + head_netmem = netmem_compound_head(shinfo->frags[i].netmem); + if (likely(is_pp_netmem(head_netmem))) + page_pool_ref_netmem(head_netmem); else - page_ref_inc(head_page); + page_ref_inc(netmem_to_page(head_netmem)); } return 0; }
Convert netmem to be a union of struct page and struct netmem. Overload the LSB of struct netmem* to indicate that it's a net_iov, otherwise it's a page. Currently these entries in struct page are rented by the page_pool and used exclusively by the net stack: struct { unsigned long pp_magic; struct page_pool *pp; unsigned long _pp_mapping_pad; unsigned long dma_addr; atomic_long_t pp_ref_count; }; Mirror these (and only these) entries into struct net_iov and implement netmem helpers that can access these common fields regardless of whether the underlying type is page or net_iov. Implement checks for net_iov in netmem helpers which delegate to mm APIs, to ensure net_iov are never passed to the mm stack. Signed-off-by: Mina Almasry <almasrymina@google.com> --- v6: - Rebased on top of the merged netmem_ref type. - Rebased on top of the merged skb_pp_frag_ref() changes. v5: - Use netmem instead of page* with LSB set. - Use pp_ref_count for refcounting net_iov. - Removed many of the custom checks for netmem. v1: - Disable fragmentation support for iov properly. - fix napi_pp_put_page() path (Yunsheng). - Use pp_frag_count for devmem refcounting. --- include/net/netmem.h | 142 ++++++++++++++++++++++++++++++-- include/net/page_pool/helpers.h | 25 +++--- include/net/page_pool/types.h | 1 + net/core/page_pool.c | 26 +++--- net/core/skbuff.c | 23 +++--- 5 files changed, 171 insertions(+), 46 deletions(-)