net/core/page_pool.c

   1 /* SPDX-License-Identifier: GPL-2.0
   2  *
   3  * page_pool.c
   4  *      Author: Jesper Dangaard Brouer <netoptimizer@brouer.com>
   5  *      Copyright (C) 2016 Red Hat, Inc.
   6  */
   7
   8 #include <linux/types.h>
   9 #include <linux/kernel.h>
  10 #include <linux/slab.h>
  11 #include <linux/device.h>
  12
  13 #include <net/page_pool.h>
  14 #include <net/xdp.h>
  15
  16 #include <linux/dma-direction.h>
  17 #include <linux/dma-mapping.h>
  18 #include <linux/page-flags.h>
  19 #include <linux/mm.h> /* for __put_page() */
  20 #include <linux/poison.h>
  21
  22 #include <trace/events/page_pool.h>
  23
  24 #define DEFER_TIME (msecs_to_jiffies(1000))
  25 #define DEFER_WARN_INTERVAL (60 * HZ)
  26
  27 #define BIAS_MAX        LONG_MAX
  28
  29 #ifdef CONFIG_PAGE_POOL_STATS
  30 /* alloc_stat_inc is intended to be used in softirq context */
  31 #define alloc_stat_inc(pool, __stat)    (pool->alloc_stats.__stat++)
  32 /* recycle_stat_inc is safe to use when preemption is possible. */
  33 #define recycle_stat_inc(pool, __stat)                                                  \
  34         do {                                                                            \
  35                 struct page_pool_recycle_stats __percpu *s = pool->recycle_stats;       \
  36                 this_cpu_inc(s->__stat);                                                \
  37         } while (0)
  38
  39 bool page_pool_get_stats(struct page_pool *pool,
  40                          struct page_pool_stats *stats)
  41 {
  42         int cpu = 0;
  43
  44         if (!stats)
  45                 return false;
  46
  47         memcpy(&stats->alloc_stats, &pool->alloc_stats, sizeof(pool->alloc_stats));
  48
  49         for_each_possible_cpu(cpu) {
  50                 const struct page_pool_recycle_stats *pcpu =
  51                         per_cpu_ptr(pool->recycle_stats, cpu);
  52
  53                 stats->recycle_stats.cached += pcpu->cached;
  54                 stats->recycle_stats.cache_full += pcpu->cache_full;
  55                 stats->recycle_stats.ring += pcpu->ring;
  56                 stats->recycle_stats.ring_full += pcpu->ring_full;
  57                 stats->recycle_stats.released_refcnt += pcpu->released_refcnt;
  58         }
  59
  60         return true;
  61 }
  62 EXPORT_SYMBOL(page_pool_get_stats);
  63 #else
  64 #define alloc_stat_inc(pool, __stat)
  65 #define recycle_stat_inc(pool, __stat)
  66 #endif
  67
  68 static int page_pool_init(struct page_pool *pool,
  69                           const struct page_pool_params *params)
  70 {
  71         unsigned int ring_qsize = 1024; /* Default */
  72
  73         memcpy(&pool->p, params, sizeof(pool->p));
  74
  75         /* Validate only known flags were used */
  76         if (pool->p.flags & ~(PP_FLAG_ALL))
  77                 return -EINVAL;
  78
  79         if (pool->p.pool_size)
  80                 ring_qsize = pool->p.pool_size;
  81
  82         /* Sanity limit mem that can be pinned down */
  83         if (ring_qsize > 32768)
  84                 return -E2BIG;
  85
  86         /* DMA direction is either DMA_FROM_DEVICE or DMA_BIDIRECTIONAL.
  87          * DMA_BIDIRECTIONAL is for allowing page used for DMA sending,
  88          * which is the XDP_TX use-case.
  89          */
  90         if (pool->p.flags & PP_FLAG_DMA_MAP) {
  91                 if ((pool->p.dma_dir != DMA_FROM_DEVICE) &&
  92                     (pool->p.dma_dir != DMA_BIDIRECTIONAL))
  93                         return -EINVAL;
  94         }
  95
  96         if (pool->p.flags & PP_FLAG_DMA_SYNC_DEV) {
  97                 /* In order to request DMA-sync-for-device the page
  98                  * needs to be mapped
  99                  */
 100                 if (!(pool->p.flags & PP_FLAG_DMA_MAP))
 101                         return -EINVAL;
 102
 103                 if (!pool->p.max_len)
 104                         return -EINVAL;
 105
 106                 /* pool->p.offset has to be set according to the address
 107                  * offset used by the DMA engine to start copying rx data
 108                  */
 109         }
 110
 111         if (PAGE_POOL_DMA_USE_PP_FRAG_COUNT &&
 112             pool->p.flags & PP_FLAG_PAGE_FRAG)
 113                 return -EINVAL;
 114
 115 #ifdef CONFIG_PAGE_POOL_STATS
 116         pool->recycle_stats = alloc_percpu(struct page_pool_recycle_stats);
 117         if (!pool->recycle_stats)
 118                 return -ENOMEM;
 119 #endif
 120
 121         if (ptr_ring_init(&pool->ring, ring_qsize, GFP_KERNEL) < 0)
 122                 return -ENOMEM;
 123
 124         atomic_set(&pool->pages_state_release_cnt, 0);
 125
 126         /* Driver calling page_pool_create() also call page_pool_destroy() */
 127         refcount_set(&pool->user_cnt, 1);
 128
 129         if (pool->p.flags & PP_FLAG_DMA_MAP)
 130                 get_device(pool->p.dev);
 131
 132         return 0;
 133 }
 134
 135 struct page_pool *page_pool_create(const struct page_pool_params *params)
 136 {
 137         struct page_pool *pool;
 138         int err;
 139
 140         pool = kzalloc_node(sizeof(*pool), GFP_KERNEL, params->nid);
 141         if (!pool)
 142                 return ERR_PTR(-ENOMEM);
 143
 144         err = page_pool_init(pool, params);
 145         if (err < 0) {
 146                 pr_warn("%s() gave up with errno %d\n", __func__, err);
 147                 kfree(pool);
 148                 return ERR_PTR(err);
 149         }
 150
 151         return pool;
 152 }
 153 EXPORT_SYMBOL(page_pool_create);
 154
 155 static void page_pool_return_page(struct page_pool *pool, struct page *page);
 156
 157 noinline
 158 static struct page *page_pool_refill_alloc_cache(struct page_pool *pool)
 159 {
 160         struct ptr_ring *r = &pool->ring;
 161         struct page *page;
 162         int pref_nid; /* preferred NUMA node */
 163
 164         /* Quicker fallback, avoid locks when ring is empty */
 165         if (__ptr_ring_empty(r)) {
 166                 alloc_stat_inc(pool, empty);
 167                 return NULL;
 168         }
 169
 170         /* Softirq guarantee CPU and thus NUMA node is stable. This,
 171          * assumes CPU refilling driver RX-ring will also run RX-NAPI.
 172          */
 173 #ifdef CONFIG_NUMA
 174         pref_nid = (pool->p.nid == NUMA_NO_NODE) ? numa_mem_id() : pool->p.nid;
 175 #else
 176         /* Ignore pool->p.nid setting if !CONFIG_NUMA, helps compiler */
 177         pref_nid = numa_mem_id(); /* will be zero like page_to_nid() */
 178 #endif
 179
 180         /* Refill alloc array, but only if NUMA match */
 181         do {
 182                 page = __ptr_ring_consume(r);
 183                 if (unlikely(!page))
 184                         break;
 185
 186                 if (likely(page_to_nid(page) == pref_nid)) {
 187                         pool->alloc.cache[pool->alloc.count++] = page;
 188                 } else {
 189                         /* NUMA mismatch;
 190                          * (1) release 1 page to page-allocator and
 191                          * (2) break out to fallthrough to alloc_pages_node.
 192                          * This limit stress on page buddy alloactor.
 193                          */
 194                         page_pool_return_page(pool, page);
 195                         alloc_stat_inc(pool, waive);
 196                         page = NULL;
 197                         break;
 198                 }
 199         } while (pool->alloc.count < PP_ALLOC_CACHE_REFILL);
 200
 201         /* Return last page */
 202         if (likely(pool->alloc.count > 0)) {
 203                 page = pool->alloc.cache[--pool->alloc.count];
 204                 alloc_stat_inc(pool, refill);
 205         }
 206
 207         return page;
 208 }
 209
 210 /* fast path */
 211 static struct page *__page_pool_get_cached(struct page_pool *pool)
 212 {
 213         struct page *page;
 214
 215         /* Caller MUST guarantee safe non-concurrent access, e.g. softirq */
 216         if (likely(pool->alloc.count)) {
 217                 /* Fast-path */
 218                 page = pool->alloc.cache[--pool->alloc.count];
 219                 alloc_stat_inc(pool, fast);
 220         } else {
 221                 page = page_pool_refill_alloc_cache(pool);
 222         }
 223
 224         return page;
 225 }
 226
 227 static void page_pool_dma_sync_for_device(struct page_pool *pool,
 228                                           struct page *page,
 229                                           unsigned int dma_sync_size)
 230 {
 231         dma_addr_t dma_addr = page_pool_get_dma_addr(page);
 232
 233         dma_sync_size = min(dma_sync_size, pool->p.max_len);
 234         dma_sync_single_range_for_device(pool->p.dev, dma_addr,
 235                                          pool->p.offset, dma_sync_size,
 236                                          pool->p.dma_dir);
 237 }
 238
 239 static bool page_pool_dma_map(struct page_pool *pool, struct page *page)
 240 {
 241         dma_addr_t dma;
 242
 243         /* Setup DMA mapping: use 'struct page' area for storing DMA-addr
 244          * since dma_addr_t can be either 32 or 64 bits and does not always fit
 245          * into page private data (i.e 32bit cpu with 64bit DMA caps)
 246          * This mapping is kept for lifetime of page, until leaving pool.
 247          */
 248         dma = dma_map_page_attrs(pool->p.dev, page, 0,
 249                                  (PAGE_SIZE << pool->p.order),
 250                                  pool->p.dma_dir, DMA_ATTR_SKIP_CPU_SYNC);
 251         if (dma_mapping_error(pool->p.dev, dma))
 252                 return false;
 253
 254         page_pool_set_dma_addr(page, dma);
 255
 256         if (pool->p.flags & PP_FLAG_DMA_SYNC_DEV)
 257                 page_pool_dma_sync_for_device(pool, page, pool->p.max_len);
 258
 259         return true;
 260 }
 261
 262 static void page_pool_set_pp_info(struct page_pool *pool,
 263                                   struct page *page)
 264 {
 265         page->pp = pool;
 266         page->pp_magic |= PP_SIGNATURE;
 267         if (pool->p.init_callback)
 268                 pool->p.init_callback(page, pool->p.init_arg);
 269 }
 270
 271 static void page_pool_clear_pp_info(struct page *page)
 272 {
 273         page->pp_magic = 0;
 274         page->pp = NULL;
 275 }
 276
 277 static struct page *__page_pool_alloc_page_order(struct page_pool *pool,
 278                                                  gfp_t gfp)
 279 {
 280         struct page *page;
 281
 282         gfp |= __GFP_COMP;
 283         page = alloc_pages_node(pool->p.nid, gfp, pool->p.order);
 284         if (unlikely(!page))
 285                 return NULL;
 286
 287         if ((pool->p.flags & PP_FLAG_DMA_MAP) &&
 288             unlikely(!page_pool_dma_map(pool, page))) {
 289                 put_page(page);
 290                 return NULL;
 291         }
 292
 293         alloc_stat_inc(pool, slow_high_order);
 294         page_pool_set_pp_info(pool, page);
 295
 296         /* Track how many pages are held 'in-flight' */
 297         pool->pages_state_hold_cnt++;
 298         trace_page_pool_state_hold(pool, page, pool->pages_state_hold_cnt);
 299         return page;
 300 }
 301
 302 /* slow path */
 303 noinline
 304 static struct page *__page_pool_alloc_pages_slow(struct page_pool *pool,
 305                                                  gfp_t gfp)
 306 {
 307         const int bulk = PP_ALLOC_CACHE_REFILL;
 308         unsigned int pp_flags = pool->p.flags;
 309         unsigned int pp_order = pool->p.order;
 310         struct page *page;
 311         int i, nr_pages;
 312
 313         /* Don't support bulk alloc for high-order pages */
 314         if (unlikely(pp_order))
 315                 return __page_pool_alloc_page_order(pool, gfp);
 316
 317         /* Unnecessary as alloc cache is empty, but guarantees zero count */
 318         if (unlikely(pool->alloc.count > 0))
 319                 return pool->alloc.cache[--pool->alloc.count];
 320
 321         /* Mark empty alloc.cache slots "empty" for alloc_pages_bulk_array */
 322         memset(&pool->alloc.cache, 0, sizeof(void *) * bulk);
 323
 324         nr_pages = alloc_pages_bulk_array(gfp, bulk, pool->alloc.cache);
 325         if (unlikely(!nr_pages))
 326                 return NULL;
 327
 328         /* Pages have been filled into alloc.cache array, but count is zero and
 329          * page element have not been (possibly) DMA mapped.
 330          */
 331         for (i = 0; i < nr_pages; i++) {
 332                 page = pool->alloc.cache[i];
 333                 if ((pp_flags & PP_FLAG_DMA_MAP) &&
 334                     unlikely(!page_pool_dma_map(pool, page))) {
 335                         put_page(page);
 336                         continue;
 337                 }
 338
 339                 page_pool_set_pp_info(pool, page);
 340                 pool->alloc.cache[pool->alloc.count++] = page;
 341                 /* Track how many pages are held 'in-flight' */
 342                 pool->pages_state_hold_cnt++;
 343                 trace_page_pool_state_hold(pool, page,
 344                                            pool->pages_state_hold_cnt);
 345         }
 346
 347         /* Return last page */
 348         if (likely(pool->alloc.count > 0)) {
 349                 page = pool->alloc.cache[--pool->alloc.count];
 350                 alloc_stat_inc(pool, slow);
 351         } else {
 352                 page = NULL;
 353         }
 354
 355         /* When page just alloc'ed is should/must have refcnt 1. */
 356         return page;
 357 }
 358
 359 /* For using page_pool replace: alloc_pages() API calls, but provide
 360  * synchronization guarantee for allocation side.
 361  */
 362 struct page *page_pool_alloc_pages(struct page_pool *pool, gfp_t gfp)
 363 {
 364         struct page *page;
 365
 366         /* Fast-path: Get a page from cache */
 367         page = __page_pool_get_cached(pool);
 368         if (page)
 369                 return page;
 370
 371         /* Slow-path: cache empty, do real allocation */
 372         page = __page_pool_alloc_pages_slow(pool, gfp);
 373         return page;
 374 }
 375 EXPORT_SYMBOL(page_pool_alloc_pages);
 376
 377 /* Calculate distance between two u32 values, valid if distance is below 2^(31)
 378  *  https://en.wikipedia.org/wiki/Serial_number_arithmetic#General_Solution
 379  */
 380 #define _distance(a, b) (s32)((a) - (b))
 381
 382 static s32 page_pool_inflight(struct page_pool *pool)
 383 {
 384         u32 release_cnt = atomic_read(&pool->pages_state_release_cnt);
 385         u32 hold_cnt = READ_ONCE(pool->pages_state_hold_cnt);
 386         s32 inflight;
 387
 388         inflight = _distance(hold_cnt, release_cnt);
 389
 390         trace_page_pool_release(pool, inflight, hold_cnt, release_cnt);
 391         WARN(inflight < 0, "Negative(%d) inflight packet-pages", inflight);
 392
 393         return inflight;
 394 }
 395
 396 /* Disconnects a page (from a page_pool).  API users can have a need
 397  * to disconnect a page (from a page_pool), to allow it to be used as
 398  * a regular page (that will eventually be returned to the normal
 399  * page-allocator via put_page).
 400  */
 401 void page_pool_release_page(struct page_pool *pool, struct page *page)
 402 {
 403         dma_addr_t dma;
 404         int count;
 405
 406         if (!(pool->p.flags & PP_FLAG_DMA_MAP))
 407                 /* Always account for inflight pages, even if we didn't
 408                  * map them
 409                  */
 410                 goto skip_dma_unmap;
 411
 412         dma = page_pool_get_dma_addr(page);
 413
 414         /* When page is unmapped, it cannot be returned to our pool */
 415         dma_unmap_page_attrs(pool->p.dev, dma,
 416                              PAGE_SIZE << pool->p.order, pool->p.dma_dir,
 417                              DMA_ATTR_SKIP_CPU_SYNC);
 418         page_pool_set_dma_addr(page, 0);
 419 skip_dma_unmap:
 420         page_pool_clear_pp_info(page);
 421
 422         /* This may be the last page returned, releasing the pool, so
 423          * it is not safe to reference pool afterwards.
 424          */
 425         count = atomic_inc_return_relaxed(&pool->pages_state_release_cnt);
 426         trace_page_pool_state_release(pool, page, count);
 427 }
 428 EXPORT_SYMBOL(page_pool_release_page);
 429
 430 /* Return a page to the page allocator, cleaning up our state */
 431 static void page_pool_return_page(struct page_pool *pool, struct page *page)
 432 {
 433         page_pool_release_page(pool, page);
 434
 435         put_page(page);
 436         /* An optimization would be to call __free_pages(page, pool->p.order)
 437          * knowing page is not part of page-cache (thus avoiding a
 438          * __page_cache_release() call).
 439          */
 440 }
 441
 442 static bool page_pool_recycle_in_ring(struct page_pool *pool, struct page *page)
 443 {
 444         int ret;
 445         /* BH protection not needed if current is serving softirq */
 446         if (in_serving_softirq())
 447                 ret = ptr_ring_produce(&pool->ring, page);
 448         else
 449                 ret = ptr_ring_produce_bh(&pool->ring, page);
 450
 451         if (!ret) {
 452                 recycle_stat_inc(pool, ring);
 453                 return true;
 454         }
 455
 456         return false;
 457 }
 458
 459 /* Only allow direct recycling in special circumstances, into the
 460  * alloc side cache.  E.g. during RX-NAPI processing for XDP_DROP use-case.
 461  *
 462  * Caller must provide appropriate safe context.
 463  */
 464 static bool page_pool_recycle_in_cache(struct page *page,
 465                                        struct page_pool *pool)
 466 {
 467         if (unlikely(pool->alloc.count == PP_ALLOC_CACHE_SIZE)) {
 468                 recycle_stat_inc(pool, cache_full);
 469                 return false;
 470         }
 471
 472         /* Caller MUST have verified/know (page_ref_count(page) == 1) */
 473         pool->alloc.cache[pool->alloc.count++] = page;
 474         recycle_stat_inc(pool, cached);
 475         return true;
 476 }
 477
 478 /* If the page refcnt == 1, this will try to recycle the page.
 479  * if PP_FLAG_DMA_SYNC_DEV is set, we'll try to sync the DMA area for
 480  * the configured size min(dma_sync_size, pool->max_len).
 481  * If the page refcnt != 1, then the page will be returned to memory
 482  * subsystem.
 483  */
 484 static __always_inline struct page *
 485 __page_pool_put_page(struct page_pool *pool, struct page *page,
 486                      unsigned int dma_sync_size, bool allow_direct)
 487 {
 488         /* This allocator is optimized for the XDP mode that uses
 489          * one-frame-per-page, but have fallbacks that act like the
 490          * regular page allocator APIs.
 491          *
 492          * refcnt == 1 means page_pool owns page, and can recycle it.
 493          *
 494          * page is NOT reusable when allocated when system is under
 495          * some pressure. (page_is_pfmemalloc)
 496          */
 497         if (likely(page_ref_count(page) == 1 && !page_is_pfmemalloc(page))) {
 498                 /* Read barrier done in page_ref_count / READ_ONCE */
 499
 500                 if (pool->p.flags & PP_FLAG_DMA_SYNC_DEV)
 501                         page_pool_dma_sync_for_device(pool, page,
 502                                                       dma_sync_size);
 503
 504                 if (allow_direct && in_serving_softirq() &&
 505                     page_pool_recycle_in_cache(page, pool))
 506                         return NULL;
 507
 508                 /* Page found as candidate for recycling */
 509                 return page;
 510         }
 511         /* Fallback/non-XDP mode: API user have elevated refcnt.
 512          *
 513          * Many drivers split up the page into fragments, and some
 514          * want to keep doing this to save memory and do refcnt based
 515          * recycling. Support this use case too, to ease drivers
 516          * switching between XDP/non-XDP.
 517          *
 518          * In-case page_pool maintains the DMA mapping, API user must
 519          * call page_pool_put_page once.  In this elevated refcnt
 520          * case, the DMA is unmapped/released, as driver is likely
 521          * doing refcnt based recycle tricks, meaning another process
 522          * will be invoking put_page.
 523          */
 524         recycle_stat_inc(pool, released_refcnt);
 525         /* Do not replace this with page_pool_return_page() */
 526         page_pool_release_page(pool, page);
 527         put_page(page);
 528
 529         return NULL;
 530 }
 531
 532 void page_pool_put_defragged_page(struct page_pool *pool, struct page *page,
 533                                   unsigned int dma_sync_size, bool allow_direct)
 534 {
 535         page = __page_pool_put_page(pool, page, dma_sync_size, allow_direct);
 536         if (page && !page_pool_recycle_in_ring(pool, page)) {
 537                 /* Cache full, fallback to free pages */
 538                 recycle_stat_inc(pool, ring_full);
 539                 page_pool_return_page(pool, page);
 540         }
 541 }
 542 EXPORT_SYMBOL(page_pool_put_defragged_page);
 543
 544 /* Caller must not use data area after call, as this function overwrites it */
 545 void page_pool_put_page_bulk(struct page_pool *pool, void **data,
 546                              int count)
 547 {
 548         int i, bulk_len = 0;
 549
 550         for (i = 0; i < count; i++) {
 551                 struct page *page = virt_to_head_page(data[i]);
 552
 553                 /* It is not the last user for the page frag case */
 554                 if (!page_pool_is_last_frag(pool, page))
 555                         continue;
 556
 557                 page = __page_pool_put_page(pool, page, -1, false);
 558                 /* Approved for bulk recycling in ptr_ring cache */
 559                 if (page)
 560                         data[bulk_len++] = page;
 561         }
 562
 563         if (unlikely(!bulk_len))
 564                 return;
 565
 566         /* Bulk producer into ptr_ring page_pool cache */
 567         page_pool_ring_lock(pool);
 568         for (i = 0; i < bulk_len; i++) {
 569                 if (__ptr_ring_produce(&pool->ring, data[i]))
 570                         break; /* ring full */
 571         }
 572         page_pool_ring_unlock(pool);
 573
 574         /* Hopefully all pages was return into ptr_ring */
 575         if (likely(i == bulk_len))
 576                 return;
 577
 578         /* ptr_ring cache full, free remaining pages outside producer lock
 579          * since put_page() with refcnt == 1 can be an expensive operation
 580          */
 581         for (; i < bulk_len; i++)
 582                 page_pool_return_page(pool, data[i]);
 583 }
 584 EXPORT_SYMBOL(page_pool_put_page_bulk);
 585
 586 static struct page *page_pool_drain_frag(struct page_pool *pool,
 587                                          struct page *page)
 588 {
 589         long drain_count = BIAS_MAX - pool->frag_users;
 590
 591         /* Some user is still using the page frag */
 592         if (likely(page_pool_defrag_page(page, drain_count)))
 593                 return NULL;
 594
 595         if (page_ref_count(page) == 1 && !page_is_pfmemalloc(page)) {
 596                 if (pool->p.flags & PP_FLAG_DMA_SYNC_DEV)
 597                         page_pool_dma_sync_for_device(pool, page, -1);
 598
 599                 return page;
 600         }
 601
 602         page_pool_return_page(pool, page);
 603         return NULL;
 604 }
 605
 606 static void page_pool_free_frag(struct page_pool *pool)
 607 {
 608         long drain_count = BIAS_MAX - pool->frag_users;
 609         struct page *page = pool->frag_page;
 610
 611         pool->frag_page = NULL;
 612
 613         if (!page || page_pool_defrag_page(page, drain_count))
 614                 return;
 615
 616         page_pool_return_page(pool, page);
 617 }
 618
 619 struct page *page_pool_alloc_frag(struct page_pool *pool,
 620                                   unsigned int *offset,
 621                                   unsigned int size, gfp_t gfp)
 622 {
 623         unsigned int max_size = PAGE_SIZE << pool->p.order;
 624         struct page *page = pool->frag_page;
 625
 626         if (WARN_ON(!(pool->p.flags & PP_FLAG_PAGE_FRAG) ||
 627                     size > max_size))
 628                 return NULL;
 629
 630         size = ALIGN(size, dma_get_cache_alignment());
 631         *offset = pool->frag_offset;
 632
 633         if (page && *offset + size > max_size) {
 634                 page = page_pool_drain_frag(pool, page);
 635                 if (page)
 636                         goto frag_reset;
 637         }
 638
 639         if (!page) {
 640                 page = page_pool_alloc_pages(pool, gfp);
 641                 if (unlikely(!page)) {
 642                         pool->frag_page = NULL;
 643                         return NULL;
 644                 }
 645
 646                 pool->frag_page = page;
 647
 648 frag_reset:
 649                 pool->frag_users = 1;
 650                 *offset = 0;
 651                 pool->frag_offset = size;
 652                 page_pool_fragment_page(page, BIAS_MAX);
 653                 return page;
 654         }
 655
 656         pool->frag_users++;
 657         pool->frag_offset = *offset + size;
 658         return page;
 659 }
 660 EXPORT_SYMBOL(page_pool_alloc_frag);
 661
 662 static void page_pool_empty_ring(struct page_pool *pool)
 663 {
 664         struct page *page;
 665
 666         /* Empty recycle ring */
 667         while ((page = ptr_ring_consume_bh(&pool->ring))) {
 668                 /* Verify the refcnt invariant of cached pages */
 669                 if (!(page_ref_count(page) == 1))
 670                         pr_crit("%s() page_pool refcnt %d violation\n",
 671                                 __func__, page_ref_count(page));
 672
 673                 page_pool_return_page(pool, page);
 674         }
 675 }
 676
 677 static void page_pool_free(struct page_pool *pool)
 678 {
 679         if (pool->disconnect)
 680                 pool->disconnect(pool);
 681
 682         ptr_ring_cleanup(&pool->ring, NULL);
 683
 684         if (pool->p.flags & PP_FLAG_DMA_MAP)
 685                 put_device(pool->p.dev);
 686
 687 #ifdef CONFIG_PAGE_POOL_STATS
 688         free_percpu(pool->recycle_stats);
 689 #endif
 690         kfree(pool);
 691 }
 692
 693 static void page_pool_empty_alloc_cache_once(struct page_pool *pool)
 694 {
 695         struct page *page;
 696
 697         if (pool->destroy_cnt)
 698                 return;
 699
 700         /* Empty alloc cache, assume caller made sure this is
 701          * no-longer in use, and page_pool_alloc_pages() cannot be
 702          * call concurrently.
 703          */
 704         while (pool->alloc.count) {
 705                 page = pool->alloc.cache[--pool->alloc.count];
 706                 page_pool_return_page(pool, page);
 707         }
 708 }
 709
 710 static void page_pool_scrub(struct page_pool *pool)
 711 {
 712         page_pool_empty_alloc_cache_once(pool);
 713         pool->destroy_cnt++;
 714
 715         /* No more consumers should exist, but producers could still
 716          * be in-flight.
 717          */
 718         page_pool_empty_ring(pool);
 719 }
 720
 721 static int page_pool_release(struct page_pool *pool)
 722 {
 723         int inflight;
 724
 725         page_pool_scrub(pool);
 726         inflight = page_pool_inflight(pool);
 727         if (!inflight)
 728                 page_pool_free(pool);
 729
 730         return inflight;
 731 }
 732
 733 static void page_pool_release_retry(struct work_struct *wq)
 734 {
 735         struct delayed_work *dwq = to_delayed_work(wq);
 736         struct page_pool *pool = container_of(dwq, typeof(*pool), release_dw);
 737         int inflight;
 738
 739         inflight = page_pool_release(pool);
 740         if (!inflight)
 741                 return;
 742
 743         /* Periodic warning */
 744         if (time_after_eq(jiffies, pool->defer_warn)) {
 745                 int sec = (s32)((u32)jiffies - (u32)pool->defer_start) / HZ;
 746
 747                 pr_warn("%s() stalled pool shutdown %d inflight %d sec\n",
 748                         __func__, inflight, sec);
 749                 pool->defer_warn = jiffies + DEFER_WARN_INTERVAL;
 750         }
 751
 752         /* Still not ready to be disconnected, retry later */
 753         schedule_delayed_work(&pool->release_dw, DEFER_TIME);
 754 }
 755
 756 void page_pool_use_xdp_mem(struct page_pool *pool, void (*disconnect)(void *),
 757                            struct xdp_mem_info *mem)
 758 {
 759         refcount_inc(&pool->user_cnt);
 760         pool->disconnect = disconnect;
 761         pool->xdp_mem_id = mem->id;
 762 }
 763
 764 void page_pool_destroy(struct page_pool *pool)
 765 {
 766         if (!pool)
 767                 return;
 768
 769         if (!page_pool_put(pool))
 770                 return;
 771
 772         page_pool_free_frag(pool);
 773
 774         if (!page_pool_release(pool))
 775                 return;
 776
 777         pool->defer_start = jiffies;
 778         pool->defer_warn  = jiffies + DEFER_WARN_INTERVAL;
 779
 780         INIT_DELAYED_WORK(&pool->release_dw, page_pool_release_retry);
 781         schedule_delayed_work(&pool->release_dw, DEFER_TIME);
 782 }
 783 EXPORT_SYMBOL(page_pool_destroy);
 784
 785 /* Caller must provide appropriate safe context, e.g. NAPI. */
 786 void page_pool_update_nid(struct page_pool *pool, int new_nid)
 787 {
 788         struct page *page;
 789
 790         trace_page_pool_update_nid(pool, new_nid);
 791         pool->p.nid = new_nid;
 792
 793         /* Flush pool alloc cache, as refill will check NUMA node */
 794         while (pool->alloc.count) {
 795                 page = pool->alloc.cache[--pool->alloc.count];
 796                 page_pool_return_page(pool, page);
 797         }
 798 }
 799 EXPORT_SYMBOL(page_pool_update_nid);
 800
 801 bool page_pool_return_skb_page(struct page *page)
 802 {
 803         struct page_pool *pp;
 804
 805         page = compound_head(page);
 806
 807         /* page->pp_magic is OR'ed with PP_SIGNATURE after the allocation
 808          * in order to preserve any existing bits, such as bit 0 for the
 809          * head page of compound page and bit 1 for pfmemalloc page, so
 810          * mask those bits for freeing side when doing below checking,
 811          * and page_is_pfmemalloc() is checked in __page_pool_put_page()
 812          * to avoid recycling the pfmemalloc page.
 813          */
 814         if (unlikely((page->pp_magic & ~0x3UL) != PP_SIGNATURE))
 815                 return false;
 816
 817         pp = page->pp;
 818
 819         /* Driver set this to memory recycling info. Reset it on recycle.
 820          * This will *not* work for NIC using a split-page memory model.
 821          * The page will be returned to the pool here regardless of the
 822          * 'flipped' fragment being in use or not.
 823          */
 824         page_pool_put_full_page(pp, page, false);
 825
 826         return true;
 827 }
 828 EXPORT_SYMBOL(page_pool_return_skb_page);