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![Yunsheng Lin](/assets/img/avatar_default.png)
There is no need to synchronize the account updating, so use the relaxed atomic to avoid some memory barrier in the data path. Acked-by: Jesper Dangaard Brouer <brouer@redhat.com> Signed-off-by: Yunsheng Lin <linyunsheng@huawei.com> Acked-by: Ilias Apalodimas <ilias.apalodimas@linaro.org> Signed-off-by: David S. Miller <davem@davemloft.net>
764 lines
20 KiB
C
764 lines
20 KiB
C
/* SPDX-License-Identifier: GPL-2.0
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*
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* page_pool.c
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* Author: Jesper Dangaard Brouer <netoptimizer@brouer.com>
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* Copyright (C) 2016 Red Hat, Inc.
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*/
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#include <linux/types.h>
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#include <linux/kernel.h>
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#include <linux/slab.h>
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#include <linux/device.h>
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#include <net/page_pool.h>
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#include <net/xdp.h>
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#include <linux/dma-direction.h>
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#include <linux/dma-mapping.h>
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#include <linux/page-flags.h>
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#include <linux/mm.h> /* for __put_page() */
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#include <linux/poison.h>
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#include <trace/events/page_pool.h>
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#define DEFER_TIME (msecs_to_jiffies(1000))
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#define DEFER_WARN_INTERVAL (60 * HZ)
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#define BIAS_MAX LONG_MAX
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static int page_pool_init(struct page_pool *pool,
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const struct page_pool_params *params)
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{
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unsigned int ring_qsize = 1024; /* Default */
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memcpy(&pool->p, params, sizeof(pool->p));
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/* Validate only known flags were used */
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if (pool->p.flags & ~(PP_FLAG_ALL))
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return -EINVAL;
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if (pool->p.pool_size)
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ring_qsize = pool->p.pool_size;
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/* Sanity limit mem that can be pinned down */
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if (ring_qsize > 32768)
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return -E2BIG;
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/* DMA direction is either DMA_FROM_DEVICE or DMA_BIDIRECTIONAL.
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* DMA_BIDIRECTIONAL is for allowing page used for DMA sending,
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* which is the XDP_TX use-case.
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*/
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if (pool->p.flags & PP_FLAG_DMA_MAP) {
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if ((pool->p.dma_dir != DMA_FROM_DEVICE) &&
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(pool->p.dma_dir != DMA_BIDIRECTIONAL))
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return -EINVAL;
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}
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if (pool->p.flags & PP_FLAG_DMA_SYNC_DEV) {
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/* In order to request DMA-sync-for-device the page
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* needs to be mapped
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*/
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if (!(pool->p.flags & PP_FLAG_DMA_MAP))
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return -EINVAL;
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if (!pool->p.max_len)
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return -EINVAL;
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/* pool->p.offset has to be set according to the address
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* offset used by the DMA engine to start copying rx data
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*/
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}
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if (PAGE_POOL_DMA_USE_PP_FRAG_COUNT &&
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pool->p.flags & PP_FLAG_PAGE_FRAG)
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return -EINVAL;
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if (ptr_ring_init(&pool->ring, ring_qsize, GFP_KERNEL) < 0)
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return -ENOMEM;
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atomic_set(&pool->pages_state_release_cnt, 0);
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/* Driver calling page_pool_create() also call page_pool_destroy() */
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refcount_set(&pool->user_cnt, 1);
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if (pool->p.flags & PP_FLAG_DMA_MAP)
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get_device(pool->p.dev);
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return 0;
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}
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struct page_pool *page_pool_create(const struct page_pool_params *params)
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{
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struct page_pool *pool;
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int err;
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pool = kzalloc_node(sizeof(*pool), GFP_KERNEL, params->nid);
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if (!pool)
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return ERR_PTR(-ENOMEM);
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err = page_pool_init(pool, params);
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if (err < 0) {
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pr_warn("%s() gave up with errno %d\n", __func__, err);
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kfree(pool);
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return ERR_PTR(err);
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}
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return pool;
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}
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EXPORT_SYMBOL(page_pool_create);
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static void page_pool_return_page(struct page_pool *pool, struct page *page);
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noinline
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static struct page *page_pool_refill_alloc_cache(struct page_pool *pool)
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{
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struct ptr_ring *r = &pool->ring;
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struct page *page;
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int pref_nid; /* preferred NUMA node */
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/* Quicker fallback, avoid locks when ring is empty */
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if (__ptr_ring_empty(r))
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return NULL;
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/* Softirq guarantee CPU and thus NUMA node is stable. This,
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* assumes CPU refilling driver RX-ring will also run RX-NAPI.
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*/
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#ifdef CONFIG_NUMA
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pref_nid = (pool->p.nid == NUMA_NO_NODE) ? numa_mem_id() : pool->p.nid;
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#else
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/* Ignore pool->p.nid setting if !CONFIG_NUMA, helps compiler */
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pref_nid = numa_mem_id(); /* will be zero like page_to_nid() */
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#endif
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/* Slower-path: Get pages from locked ring queue */
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spin_lock(&r->consumer_lock);
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/* Refill alloc array, but only if NUMA match */
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do {
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page = __ptr_ring_consume(r);
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if (unlikely(!page))
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break;
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if (likely(page_to_nid(page) == pref_nid)) {
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pool->alloc.cache[pool->alloc.count++] = page;
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} else {
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/* NUMA mismatch;
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* (1) release 1 page to page-allocator and
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* (2) break out to fallthrough to alloc_pages_node.
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* This limit stress on page buddy alloactor.
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*/
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page_pool_return_page(pool, page);
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page = NULL;
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break;
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}
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} while (pool->alloc.count < PP_ALLOC_CACHE_REFILL);
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/* Return last page */
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if (likely(pool->alloc.count > 0))
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page = pool->alloc.cache[--pool->alloc.count];
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spin_unlock(&r->consumer_lock);
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return page;
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}
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/* fast path */
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static struct page *__page_pool_get_cached(struct page_pool *pool)
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{
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struct page *page;
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/* Caller MUST guarantee safe non-concurrent access, e.g. softirq */
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if (likely(pool->alloc.count)) {
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/* Fast-path */
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page = pool->alloc.cache[--pool->alloc.count];
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} else {
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page = page_pool_refill_alloc_cache(pool);
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}
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return page;
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}
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static void page_pool_dma_sync_for_device(struct page_pool *pool,
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struct page *page,
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unsigned int dma_sync_size)
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{
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dma_addr_t dma_addr = page_pool_get_dma_addr(page);
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dma_sync_size = min(dma_sync_size, pool->p.max_len);
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dma_sync_single_range_for_device(pool->p.dev, dma_addr,
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pool->p.offset, dma_sync_size,
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pool->p.dma_dir);
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}
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static bool page_pool_dma_map(struct page_pool *pool, struct page *page)
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{
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dma_addr_t dma;
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/* Setup DMA mapping: use 'struct page' area for storing DMA-addr
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* since dma_addr_t can be either 32 or 64 bits and does not always fit
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* into page private data (i.e 32bit cpu with 64bit DMA caps)
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* This mapping is kept for lifetime of page, until leaving pool.
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*/
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dma = dma_map_page_attrs(pool->p.dev, page, 0,
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(PAGE_SIZE << pool->p.order),
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pool->p.dma_dir, DMA_ATTR_SKIP_CPU_SYNC);
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if (dma_mapping_error(pool->p.dev, dma))
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return false;
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page_pool_set_dma_addr(page, dma);
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if (pool->p.flags & PP_FLAG_DMA_SYNC_DEV)
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page_pool_dma_sync_for_device(pool, page, pool->p.max_len);
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return true;
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}
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static void page_pool_set_pp_info(struct page_pool *pool,
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struct page *page)
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{
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page->pp = pool;
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page->pp_magic |= PP_SIGNATURE;
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}
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static void page_pool_clear_pp_info(struct page *page)
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{
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page->pp_magic = 0;
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page->pp = NULL;
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}
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static struct page *__page_pool_alloc_page_order(struct page_pool *pool,
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gfp_t gfp)
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{
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struct page *page;
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gfp |= __GFP_COMP;
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page = alloc_pages_node(pool->p.nid, gfp, pool->p.order);
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if (unlikely(!page))
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return NULL;
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if ((pool->p.flags & PP_FLAG_DMA_MAP) &&
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unlikely(!page_pool_dma_map(pool, page))) {
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put_page(page);
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return NULL;
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}
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page_pool_set_pp_info(pool, page);
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/* Track how many pages are held 'in-flight' */
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pool->pages_state_hold_cnt++;
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trace_page_pool_state_hold(pool, page, pool->pages_state_hold_cnt);
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return page;
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}
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/* slow path */
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noinline
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static struct page *__page_pool_alloc_pages_slow(struct page_pool *pool,
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gfp_t gfp)
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{
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const int bulk = PP_ALLOC_CACHE_REFILL;
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unsigned int pp_flags = pool->p.flags;
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unsigned int pp_order = pool->p.order;
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struct page *page;
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int i, nr_pages;
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/* Don't support bulk alloc for high-order pages */
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if (unlikely(pp_order))
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return __page_pool_alloc_page_order(pool, gfp);
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/* Unnecessary as alloc cache is empty, but guarantees zero count */
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if (unlikely(pool->alloc.count > 0))
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return pool->alloc.cache[--pool->alloc.count];
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/* Mark empty alloc.cache slots "empty" for alloc_pages_bulk_array */
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memset(&pool->alloc.cache, 0, sizeof(void *) * bulk);
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nr_pages = alloc_pages_bulk_array(gfp, bulk, pool->alloc.cache);
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if (unlikely(!nr_pages))
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return NULL;
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/* Pages have been filled into alloc.cache array, but count is zero and
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* page element have not been (possibly) DMA mapped.
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*/
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for (i = 0; i < nr_pages; i++) {
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page = pool->alloc.cache[i];
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if ((pp_flags & PP_FLAG_DMA_MAP) &&
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unlikely(!page_pool_dma_map(pool, page))) {
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put_page(page);
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continue;
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}
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page_pool_set_pp_info(pool, page);
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pool->alloc.cache[pool->alloc.count++] = page;
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/* Track how many pages are held 'in-flight' */
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pool->pages_state_hold_cnt++;
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trace_page_pool_state_hold(pool, page,
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pool->pages_state_hold_cnt);
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}
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/* Return last page */
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if (likely(pool->alloc.count > 0))
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page = pool->alloc.cache[--pool->alloc.count];
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else
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page = NULL;
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/* When page just alloc'ed is should/must have refcnt 1. */
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return page;
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}
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/* For using page_pool replace: alloc_pages() API calls, but provide
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* synchronization guarantee for allocation side.
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*/
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struct page *page_pool_alloc_pages(struct page_pool *pool, gfp_t gfp)
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{
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struct page *page;
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/* Fast-path: Get a page from cache */
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page = __page_pool_get_cached(pool);
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if (page)
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return page;
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/* Slow-path: cache empty, do real allocation */
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page = __page_pool_alloc_pages_slow(pool, gfp);
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return page;
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}
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EXPORT_SYMBOL(page_pool_alloc_pages);
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/* Calculate distance between two u32 values, valid if distance is below 2^(31)
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* https://en.wikipedia.org/wiki/Serial_number_arithmetic#General_Solution
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*/
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#define _distance(a, b) (s32)((a) - (b))
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static s32 page_pool_inflight(struct page_pool *pool)
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{
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u32 release_cnt = atomic_read(&pool->pages_state_release_cnt);
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u32 hold_cnt = READ_ONCE(pool->pages_state_hold_cnt);
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s32 inflight;
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inflight = _distance(hold_cnt, release_cnt);
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trace_page_pool_release(pool, inflight, hold_cnt, release_cnt);
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WARN(inflight < 0, "Negative(%d) inflight packet-pages", inflight);
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return inflight;
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}
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/* Disconnects a page (from a page_pool). API users can have a need
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* to disconnect a page (from a page_pool), to allow it to be used as
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* a regular page (that will eventually be returned to the normal
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* page-allocator via put_page).
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*/
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void page_pool_release_page(struct page_pool *pool, struct page *page)
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{
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dma_addr_t dma;
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int count;
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if (!(pool->p.flags & PP_FLAG_DMA_MAP))
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/* Always account for inflight pages, even if we didn't
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* map them
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*/
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goto skip_dma_unmap;
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dma = page_pool_get_dma_addr(page);
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/* When page is unmapped, it cannot be returned to our pool */
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dma_unmap_page_attrs(pool->p.dev, dma,
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PAGE_SIZE << pool->p.order, pool->p.dma_dir,
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DMA_ATTR_SKIP_CPU_SYNC);
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page_pool_set_dma_addr(page, 0);
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skip_dma_unmap:
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page_pool_clear_pp_info(page);
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/* This may be the last page returned, releasing the pool, so
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* it is not safe to reference pool afterwards.
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*/
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count = atomic_inc_return_relaxed(&pool->pages_state_release_cnt);
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trace_page_pool_state_release(pool, page, count);
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}
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EXPORT_SYMBOL(page_pool_release_page);
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/* Return a page to the page allocator, cleaning up our state */
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static void page_pool_return_page(struct page_pool *pool, struct page *page)
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{
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page_pool_release_page(pool, page);
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put_page(page);
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/* An optimization would be to call __free_pages(page, pool->p.order)
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* knowing page is not part of page-cache (thus avoiding a
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* __page_cache_release() call).
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*/
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}
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static bool page_pool_recycle_in_ring(struct page_pool *pool, struct page *page)
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{
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int ret;
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/* BH protection not needed if current is serving softirq */
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if (in_serving_softirq())
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ret = ptr_ring_produce(&pool->ring, page);
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else
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ret = ptr_ring_produce_bh(&pool->ring, page);
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return (ret == 0) ? true : false;
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}
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/* Only allow direct recycling in special circumstances, into the
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* alloc side cache. E.g. during RX-NAPI processing for XDP_DROP use-case.
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*
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* Caller must provide appropriate safe context.
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*/
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static bool page_pool_recycle_in_cache(struct page *page,
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struct page_pool *pool)
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{
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if (unlikely(pool->alloc.count == PP_ALLOC_CACHE_SIZE))
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return false;
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/* Caller MUST have verified/know (page_ref_count(page) == 1) */
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pool->alloc.cache[pool->alloc.count++] = page;
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return true;
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}
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/* If the page refcnt == 1, this will try to recycle the page.
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* if PP_FLAG_DMA_SYNC_DEV is set, we'll try to sync the DMA area for
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* the configured size min(dma_sync_size, pool->max_len).
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* If the page refcnt != 1, then the page will be returned to memory
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* subsystem.
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*/
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static __always_inline struct page *
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__page_pool_put_page(struct page_pool *pool, struct page *page,
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unsigned int dma_sync_size, bool allow_direct)
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{
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/* It is not the last user for the page frag case */
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if (pool->p.flags & PP_FLAG_PAGE_FRAG &&
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page_pool_atomic_sub_frag_count_return(page, 1))
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return NULL;
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/* This allocator is optimized for the XDP mode that uses
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* one-frame-per-page, but have fallbacks that act like the
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* regular page allocator APIs.
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*
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* refcnt == 1 means page_pool owns page, and can recycle it.
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*
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* page is NOT reusable when allocated when system is under
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* some pressure. (page_is_pfmemalloc)
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*/
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if (likely(page_ref_count(page) == 1 && !page_is_pfmemalloc(page))) {
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/* Read barrier done in page_ref_count / READ_ONCE */
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if (pool->p.flags & PP_FLAG_DMA_SYNC_DEV)
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page_pool_dma_sync_for_device(pool, page,
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dma_sync_size);
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if (allow_direct && in_serving_softirq() &&
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page_pool_recycle_in_cache(page, pool))
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return NULL;
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/* Page found as candidate for recycling */
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return page;
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}
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/* Fallback/non-XDP mode: API user have elevated refcnt.
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*
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* Many drivers split up the page into fragments, and some
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* want to keep doing this to save memory and do refcnt based
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* recycling. Support this use case too, to ease drivers
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* switching between XDP/non-XDP.
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*
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* In-case page_pool maintains the DMA mapping, API user must
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* call page_pool_put_page once. In this elevated refcnt
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* case, the DMA is unmapped/released, as driver is likely
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* doing refcnt based recycle tricks, meaning another process
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* will be invoking put_page.
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*/
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/* Do not replace this with page_pool_return_page() */
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page_pool_release_page(pool, page);
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put_page(page);
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return NULL;
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}
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void page_pool_put_page(struct page_pool *pool, struct page *page,
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unsigned int dma_sync_size, bool allow_direct)
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{
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page = __page_pool_put_page(pool, page, dma_sync_size, allow_direct);
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if (page && !page_pool_recycle_in_ring(pool, page)) {
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/* Cache full, fallback to free pages */
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page_pool_return_page(pool, page);
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}
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}
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EXPORT_SYMBOL(page_pool_put_page);
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/* Caller must not use data area after call, as this function overwrites it */
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void page_pool_put_page_bulk(struct page_pool *pool, void **data,
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int count)
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{
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int i, bulk_len = 0;
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|
|
for (i = 0; i < count; i++) {
|
|
struct page *page = virt_to_head_page(data[i]);
|
|
|
|
page = __page_pool_put_page(pool, page, -1, false);
|
|
/* Approved for bulk recycling in ptr_ring cache */
|
|
if (page)
|
|
data[bulk_len++] = page;
|
|
}
|
|
|
|
if (unlikely(!bulk_len))
|
|
return;
|
|
|
|
/* Bulk producer into ptr_ring page_pool cache */
|
|
page_pool_ring_lock(pool);
|
|
for (i = 0; i < bulk_len; i++) {
|
|
if (__ptr_ring_produce(&pool->ring, data[i]))
|
|
break; /* ring full */
|
|
}
|
|
page_pool_ring_unlock(pool);
|
|
|
|
/* Hopefully all pages was return into ptr_ring */
|
|
if (likely(i == bulk_len))
|
|
return;
|
|
|
|
/* ptr_ring cache full, free remaining pages outside producer lock
|
|
* since put_page() with refcnt == 1 can be an expensive operation
|
|
*/
|
|
for (; i < bulk_len; i++)
|
|
page_pool_return_page(pool, data[i]);
|
|
}
|
|
EXPORT_SYMBOL(page_pool_put_page_bulk);
|
|
|
|
static struct page *page_pool_drain_frag(struct page_pool *pool,
|
|
struct page *page)
|
|
{
|
|
long drain_count = BIAS_MAX - pool->frag_users;
|
|
|
|
/* Some user is still using the page frag */
|
|
if (likely(page_pool_atomic_sub_frag_count_return(page,
|
|
drain_count)))
|
|
return NULL;
|
|
|
|
if (page_ref_count(page) == 1 && !page_is_pfmemalloc(page)) {
|
|
if (pool->p.flags & PP_FLAG_DMA_SYNC_DEV)
|
|
page_pool_dma_sync_for_device(pool, page, -1);
|
|
|
|
return page;
|
|
}
|
|
|
|
page_pool_return_page(pool, page);
|
|
return NULL;
|
|
}
|
|
|
|
static void page_pool_free_frag(struct page_pool *pool)
|
|
{
|
|
long drain_count = BIAS_MAX - pool->frag_users;
|
|
struct page *page = pool->frag_page;
|
|
|
|
pool->frag_page = NULL;
|
|
|
|
if (!page ||
|
|
page_pool_atomic_sub_frag_count_return(page, drain_count))
|
|
return;
|
|
|
|
page_pool_return_page(pool, page);
|
|
}
|
|
|
|
struct page *page_pool_alloc_frag(struct page_pool *pool,
|
|
unsigned int *offset,
|
|
unsigned int size, gfp_t gfp)
|
|
{
|
|
unsigned int max_size = PAGE_SIZE << pool->p.order;
|
|
struct page *page = pool->frag_page;
|
|
|
|
if (WARN_ON(!(pool->p.flags & PP_FLAG_PAGE_FRAG) ||
|
|
size > max_size))
|
|
return NULL;
|
|
|
|
size = ALIGN(size, dma_get_cache_alignment());
|
|
*offset = pool->frag_offset;
|
|
|
|
if (page && *offset + size > max_size) {
|
|
page = page_pool_drain_frag(pool, page);
|
|
if (page)
|
|
goto frag_reset;
|
|
}
|
|
|
|
if (!page) {
|
|
page = page_pool_alloc_pages(pool, gfp);
|
|
if (unlikely(!page)) {
|
|
pool->frag_page = NULL;
|
|
return NULL;
|
|
}
|
|
|
|
pool->frag_page = page;
|
|
|
|
frag_reset:
|
|
pool->frag_users = 1;
|
|
*offset = 0;
|
|
pool->frag_offset = size;
|
|
page_pool_set_frag_count(page, BIAS_MAX);
|
|
return page;
|
|
}
|
|
|
|
pool->frag_users++;
|
|
pool->frag_offset = *offset + size;
|
|
return page;
|
|
}
|
|
EXPORT_SYMBOL(page_pool_alloc_frag);
|
|
|
|
static void page_pool_empty_ring(struct page_pool *pool)
|
|
{
|
|
struct page *page;
|
|
|
|
/* Empty recycle ring */
|
|
while ((page = ptr_ring_consume_bh(&pool->ring))) {
|
|
/* Verify the refcnt invariant of cached pages */
|
|
if (!(page_ref_count(page) == 1))
|
|
pr_crit("%s() page_pool refcnt %d violation\n",
|
|
__func__, page_ref_count(page));
|
|
|
|
page_pool_return_page(pool, page);
|
|
}
|
|
}
|
|
|
|
static void page_pool_free(struct page_pool *pool)
|
|
{
|
|
if (pool->disconnect)
|
|
pool->disconnect(pool);
|
|
|
|
ptr_ring_cleanup(&pool->ring, NULL);
|
|
|
|
if (pool->p.flags & PP_FLAG_DMA_MAP)
|
|
put_device(pool->p.dev);
|
|
|
|
kfree(pool);
|
|
}
|
|
|
|
static void page_pool_empty_alloc_cache_once(struct page_pool *pool)
|
|
{
|
|
struct page *page;
|
|
|
|
if (pool->destroy_cnt)
|
|
return;
|
|
|
|
/* Empty alloc cache, assume caller made sure this is
|
|
* no-longer in use, and page_pool_alloc_pages() cannot be
|
|
* call concurrently.
|
|
*/
|
|
while (pool->alloc.count) {
|
|
page = pool->alloc.cache[--pool->alloc.count];
|
|
page_pool_return_page(pool, page);
|
|
}
|
|
}
|
|
|
|
static void page_pool_scrub(struct page_pool *pool)
|
|
{
|
|
page_pool_empty_alloc_cache_once(pool);
|
|
pool->destroy_cnt++;
|
|
|
|
/* No more consumers should exist, but producers could still
|
|
* be in-flight.
|
|
*/
|
|
page_pool_empty_ring(pool);
|
|
}
|
|
|
|
static int page_pool_release(struct page_pool *pool)
|
|
{
|
|
int inflight;
|
|
|
|
page_pool_scrub(pool);
|
|
inflight = page_pool_inflight(pool);
|
|
if (!inflight)
|
|
page_pool_free(pool);
|
|
|
|
return inflight;
|
|
}
|
|
|
|
static void page_pool_release_retry(struct work_struct *wq)
|
|
{
|
|
struct delayed_work *dwq = to_delayed_work(wq);
|
|
struct page_pool *pool = container_of(dwq, typeof(*pool), release_dw);
|
|
int inflight;
|
|
|
|
inflight = page_pool_release(pool);
|
|
if (!inflight)
|
|
return;
|
|
|
|
/* Periodic warning */
|
|
if (time_after_eq(jiffies, pool->defer_warn)) {
|
|
int sec = (s32)((u32)jiffies - (u32)pool->defer_start) / HZ;
|
|
|
|
pr_warn("%s() stalled pool shutdown %d inflight %d sec\n",
|
|
__func__, inflight, sec);
|
|
pool->defer_warn = jiffies + DEFER_WARN_INTERVAL;
|
|
}
|
|
|
|
/* Still not ready to be disconnected, retry later */
|
|
schedule_delayed_work(&pool->release_dw, DEFER_TIME);
|
|
}
|
|
|
|
void page_pool_use_xdp_mem(struct page_pool *pool, void (*disconnect)(void *))
|
|
{
|
|
refcount_inc(&pool->user_cnt);
|
|
pool->disconnect = disconnect;
|
|
}
|
|
|
|
void page_pool_destroy(struct page_pool *pool)
|
|
{
|
|
if (!pool)
|
|
return;
|
|
|
|
if (!page_pool_put(pool))
|
|
return;
|
|
|
|
page_pool_free_frag(pool);
|
|
|
|
if (!page_pool_release(pool))
|
|
return;
|
|
|
|
pool->defer_start = jiffies;
|
|
pool->defer_warn = jiffies + DEFER_WARN_INTERVAL;
|
|
|
|
INIT_DELAYED_WORK(&pool->release_dw, page_pool_release_retry);
|
|
schedule_delayed_work(&pool->release_dw, DEFER_TIME);
|
|
}
|
|
EXPORT_SYMBOL(page_pool_destroy);
|
|
|
|
/* Caller must provide appropriate safe context, e.g. NAPI. */
|
|
void page_pool_update_nid(struct page_pool *pool, int new_nid)
|
|
{
|
|
struct page *page;
|
|
|
|
trace_page_pool_update_nid(pool, new_nid);
|
|
pool->p.nid = new_nid;
|
|
|
|
/* Flush pool alloc cache, as refill will check NUMA node */
|
|
while (pool->alloc.count) {
|
|
page = pool->alloc.cache[--pool->alloc.count];
|
|
page_pool_return_page(pool, page);
|
|
}
|
|
}
|
|
EXPORT_SYMBOL(page_pool_update_nid);
|
|
|
|
bool page_pool_return_skb_page(struct page *page)
|
|
{
|
|
struct page_pool *pp;
|
|
|
|
page = compound_head(page);
|
|
|
|
/* 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
|
|
* head page of compound page and bit 1 for pfmemalloc page, so
|
|
* mask those bits for freeing side when doing below checking,
|
|
* and page_is_pfmemalloc() is checked in __page_pool_put_page()
|
|
* to avoid recycling the pfmemalloc page.
|
|
*/
|
|
if (unlikely((page->pp_magic & ~0x3UL) != PP_SIGNATURE))
|
|
return false;
|
|
|
|
pp = page->pp;
|
|
|
|
/* Driver set this to memory recycling info. Reset it on recycle.
|
|
* This will *not* work for NIC using a split-page memory model.
|
|
* The page will be returned to the pool here regardless of the
|
|
* 'flipped' fragment being in use or not.
|
|
*/
|
|
page_pool_put_full_page(pp, page, false);
|
|
|
|
return true;
|
|
}
|
|
EXPORT_SYMBOL(page_pool_return_skb_page);
|