linux/net/core/page_pool.c

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page_pool: refurbish version of page_pool code Need a fast page recycle mechanism for ndo_xdp_xmit API for returning pages on DMA-TX completion time, which have good cross CPU performance, given DMA-TX completion time can happen on a remote CPU. Refurbish my page_pool code, that was presented[1] at MM-summit 2016. Adapted page_pool code to not depend the page allocator and integration into struct page. The DMA mapping feature is kept, even-though it will not be activated/used in this patchset. [1] http://people.netfilter.org/hawk/presentations/MM-summit2016/generic_page_pool_mm_summit2016.pdf V2: Adjustments requested by Tariq - Changed page_pool_create return codes, don't return NULL, only ERR_PTR, as this simplifies err handling in drivers. V4: many small improvements and cleanups - Add DOC comment section, that can be used by kernel-doc - Improve fallback mode, to work better with refcnt based recycling e.g. remove a WARN as pointed out by Tariq e.g. quicker fallback if ptr_ring is empty. V5: Fixed SPDX license as pointed out by Alexei V6: Adjustments requested by Eric Dumazet - Adjust ____cacheline_aligned_in_smp usage/placement - Move rcu_head in struct page_pool - Free pages quicker on destroy, minimize resources delayed an RCU period - Remove code for forward/backward compat ABI interface V8: Issues found by kbuild test robot - Address sparse should be static warnings - Only compile+link when a driver use/select page_pool, mlx5 selects CONFIG_PAGE_POOL, although its first used in two patches Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2018-04-17 14:46:17 +00:00
/* SPDX-License-Identifier: GPL-2.0
*
* page_pool.c
* Author: Jesper Dangaard Brouer <netoptimizer@brouer.com>
* Copyright (C) 2016 Red Hat, Inc.
*/
#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/slab.h>
#include <net/page_pool.h>
#include <linux/dma-direction.h>
#include <linux/dma-mapping.h>
#include <linux/page-flags.h>
#include <linux/mm.h> /* for __put_page() */
static int page_pool_init(struct page_pool *pool,
const struct page_pool_params *params)
{
unsigned int ring_qsize = 1024; /* Default */
memcpy(&pool->p, params, sizeof(pool->p));
/* Validate only known flags were used */
if (pool->p.flags & ~(PP_FLAG_ALL))
return -EINVAL;
if (pool->p.pool_size)
ring_qsize = pool->p.pool_size;
/* Sanity limit mem that can be pinned down */
if (ring_qsize > 32768)
return -E2BIG;
/* DMA direction is either DMA_FROM_DEVICE or DMA_BIDIRECTIONAL.
* DMA_BIDIRECTIONAL is for allowing page used for DMA sending,
* which is the XDP_TX use-case.
*/
if ((pool->p.dma_dir != DMA_FROM_DEVICE) &&
(pool->p.dma_dir != DMA_BIDIRECTIONAL))
return -EINVAL;
if (ptr_ring_init(&pool->ring, ring_qsize, GFP_KERNEL) < 0)
return -ENOMEM;
return 0;
}
struct page_pool *page_pool_create(const struct page_pool_params *params)
{
struct page_pool *pool;
int err = 0;
pool = kzalloc_node(sizeof(*pool), GFP_KERNEL, params->nid);
if (!pool)
return ERR_PTR(-ENOMEM);
err = page_pool_init(pool, params);
if (err < 0) {
pr_warn("%s() gave up with errno %d\n", __func__, err);
kfree(pool);
return ERR_PTR(err);
}
return pool;
}
EXPORT_SYMBOL(page_pool_create);
/* fast path */
static struct page *__page_pool_get_cached(struct page_pool *pool)
{
struct ptr_ring *r = &pool->ring;
struct page *page;
/* Quicker fallback, avoid locks when ring is empty */
if (__ptr_ring_empty(r))
return NULL;
/* Test for safe-context, caller should provide this guarantee */
if (likely(in_serving_softirq())) {
if (likely(pool->alloc.count)) {
/* Fast-path */
page = pool->alloc.cache[--pool->alloc.count];
return page;
}
/* Slower-path: Alloc array empty, time to refill
*
* Open-coded bulk ptr_ring consumer.
*
* Discussion: the ring consumer lock is not really
* needed due to the softirq/NAPI protection, but
* later need the ability to reclaim pages on the
* ring. Thus, keeping the locks.
*/
spin_lock(&r->consumer_lock);
while ((page = __ptr_ring_consume(r))) {
if (pool->alloc.count == PP_ALLOC_CACHE_REFILL)
break;
pool->alloc.cache[pool->alloc.count++] = page;
}
spin_unlock(&r->consumer_lock);
return page;
}
/* Slow-path: Get page from locked ring queue */
page = ptr_ring_consume(&pool->ring);
return page;
}
/* slow path */
noinline
static struct page *__page_pool_alloc_pages_slow(struct page_pool *pool,
gfp_t _gfp)
{
struct page *page;
gfp_t gfp = _gfp;
dma_addr_t dma;
/* We could always set __GFP_COMP, and avoid this branch, as
* prep_new_page() can handle order-0 with __GFP_COMP.
*/
if (pool->p.order)
gfp |= __GFP_COMP;
/* FUTURE development:
*
* Current slow-path essentially falls back to single page
* allocations, which doesn't improve performance. This code
* need bulk allocation support from the page allocator code.
*/
/* Cache was empty, do real allocation */
page = alloc_pages_node(pool->p.nid, gfp, pool->p.order);
if (!page)
return NULL;
if (!(pool->p.flags & PP_FLAG_DMA_MAP))
goto skip_dma_map;
/* Setup DMA mapping: use page->private for DMA-addr
* This mapping is kept for lifetime of page, until leaving pool.
*/
dma = dma_map_page(pool->p.dev, page, 0,
(PAGE_SIZE << pool->p.order),
pool->p.dma_dir);
if (dma_mapping_error(pool->p.dev, dma)) {
put_page(page);
return NULL;
}
set_page_private(page, dma); /* page->private = dma; */
skip_dma_map:
/* When page just alloc'ed is should/must have refcnt 1. */
return page;
}
/* For using page_pool replace: alloc_pages() API calls, but provide
* synchronization guarantee for allocation side.
*/
struct page *page_pool_alloc_pages(struct page_pool *pool, gfp_t gfp)
{
struct page *page;
/* Fast-path: Get a page from cache */
page = __page_pool_get_cached(pool);
if (page)
return page;
/* Slow-path: cache empty, do real allocation */
page = __page_pool_alloc_pages_slow(pool, gfp);
return page;
}
EXPORT_SYMBOL(page_pool_alloc_pages);
/* Cleanup page_pool state from page */
static void __page_pool_clean_page(struct page_pool *pool,
struct page *page)
{
if (!(pool->p.flags & PP_FLAG_DMA_MAP))
return;
/* DMA unmap */
dma_unmap_page(pool->p.dev, page_private(page),
PAGE_SIZE << pool->p.order, pool->p.dma_dir);
set_page_private(page, 0);
}
/* Return a page to the page allocator, cleaning up our state */
static void __page_pool_return_page(struct page_pool *pool, struct page *page)
{
__page_pool_clean_page(pool, page);
put_page(page);
/* An optimization would be to call __free_pages(page, pool->p.order)
* knowing page is not part of page-cache (thus avoiding a
* __page_cache_release() call).
*/
}
static bool __page_pool_recycle_into_ring(struct page_pool *pool,
struct page *page)
{
int ret;
/* BH protection not needed if current is serving softirq */
if (in_serving_softirq())
ret = ptr_ring_produce(&pool->ring, page);
else
ret = ptr_ring_produce_bh(&pool->ring, page);
return (ret == 0) ? true : false;
}
/* Only allow direct recycling in special circumstances, into the
* alloc side cache. E.g. during RX-NAPI processing for XDP_DROP use-case.
*
* Caller must provide appropriate safe context.
*/
static bool __page_pool_recycle_direct(struct page *page,
struct page_pool *pool)
{
if (unlikely(pool->alloc.count == PP_ALLOC_CACHE_SIZE))
return false;
/* Caller MUST have verified/know (page_ref_count(page) == 1) */
pool->alloc.cache[pool->alloc.count++] = page;
return true;
}
void __page_pool_put_page(struct page_pool *pool,
struct page *page, bool allow_direct)
{
/* This allocator is optimized for the XDP mode that uses
* one-frame-per-page, but have fallbacks that act like the
* regular page allocator APIs.
*
* refcnt == 1 means page_pool owns page, and can recycle it.
*/
if (likely(page_ref_count(page) == 1)) {
/* Read barrier done in page_ref_count / READ_ONCE */
if (allow_direct && in_serving_softirq())
if (__page_pool_recycle_direct(page, pool))
return;
if (!__page_pool_recycle_into_ring(pool, page)) {
/* Cache full, fallback to free pages */
__page_pool_return_page(pool, page);
}
return;
}
/* Fallback/non-XDP mode: API user have elevated refcnt.
*
* Many drivers split up the page into fragments, and some
* want to keep doing this to save memory and do refcnt based
* recycling. Support this use case too, to ease drivers
* switching between XDP/non-XDP.
*
* In-case page_pool maintains the DMA mapping, API user must
* call page_pool_put_page once. In this elevated refcnt
* case, the DMA is unmapped/released, as driver is likely
* doing refcnt based recycle tricks, meaning another process
* will be invoking put_page.
*/
__page_pool_clean_page(pool, page);
put_page(page);
}
EXPORT_SYMBOL(__page_pool_put_page);
static void __page_pool_empty_ring(struct page_pool *pool)
{
struct page *page;
/* Empty recycle ring */
net/page_pool: Fix inconsistent lock state warning Fix the warning below by calling the ptr_ring_consume_bh, which uses spin_[un]lock_bh. [ 179.064300] ================================ [ 179.069073] WARNING: inconsistent lock state [ 179.073846] 4.18.0-rc2+ #18 Not tainted [ 179.078133] -------------------------------- [ 179.082907] inconsistent {SOFTIRQ-ON-W} -> {IN-SOFTIRQ-W} usage. [ 179.089637] swapper/21/0 [HC0[0]:SC1[1]:HE1:SE0] takes: [ 179.095478] 00000000963d1995 (&(&r->consumer_lock)->rlock){+.?.}, at: __page_pool_empty_ring+0x61/0x100 [ 179.105988] {SOFTIRQ-ON-W} state was registered at: [ 179.111443] _raw_spin_lock+0x35/0x50 [ 179.115634] __page_pool_empty_ring+0x61/0x100 [ 179.120699] page_pool_destroy+0x32/0x50 [ 179.125204] mlx5e_free_rq+0x38/0xc0 [mlx5_core] [ 179.130471] mlx5e_close_channel+0x20/0x120 [mlx5_core] [ 179.136418] mlx5e_close_channels+0x26/0x40 [mlx5_core] [ 179.142364] mlx5e_close_locked+0x44/0x50 [mlx5_core] [ 179.148509] mlx5e_close+0x42/0x60 [mlx5_core] [ 179.153936] __dev_close_many+0xb1/0x120 [ 179.158749] dev_close_many+0xa2/0x170 [ 179.163364] rollback_registered_many+0x148/0x460 [ 179.169047] rollback_registered+0x56/0x90 [ 179.174043] unregister_netdevice_queue+0x7e/0x100 [ 179.179816] unregister_netdev+0x18/0x20 [ 179.184623] mlx5e_remove+0x2a/0x50 [mlx5_core] [ 179.190107] mlx5_remove_device+0xe5/0x110 [mlx5_core] [ 179.196274] mlx5_unregister_interface+0x39/0x90 [mlx5_core] [ 179.203028] cleanup+0x5/0xbfc [mlx5_core] [ 179.208031] __x64_sys_delete_module+0x16b/0x240 [ 179.213640] do_syscall_64+0x5a/0x210 [ 179.218151] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 179.224218] irq event stamp: 334398 [ 179.228438] hardirqs last enabled at (334398): [<ffffffffa511d8b7>] rcu_process_callbacks+0x1c7/0x790 [ 179.239178] hardirqs last disabled at (334397): [<ffffffffa511d872>] rcu_process_callbacks+0x182/0x790 [ 179.249931] softirqs last enabled at (334386): [<ffffffffa509732e>] irq_enter+0x5e/0x70 [ 179.259306] softirqs last disabled at (334387): [<ffffffffa509741c>] irq_exit+0xdc/0xf0 [ 179.268584] [ 179.268584] other info that might help us debug this: [ 179.276572] Possible unsafe locking scenario: [ 179.276572] [ 179.283877] CPU0 [ 179.286954] ---- [ 179.290033] lock(&(&r->consumer_lock)->rlock); [ 179.295546] <Interrupt> [ 179.298830] lock(&(&r->consumer_lock)->rlock); [ 179.304550] [ 179.304550] *** DEADLOCK *** Fixes: ff7d6b27f894 ("page_pool: refurbish version of page_pool code") Signed-off-by: Tariq Toukan <tariqt@mellanox.com> Cc: Jesper Dangaard Brouer <brouer@redhat.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2018-07-17 15:10:37 +00:00
while ((page = ptr_ring_consume_bh(&pool->ring))) {
page_pool: refurbish version of page_pool code Need a fast page recycle mechanism for ndo_xdp_xmit API for returning pages on DMA-TX completion time, which have good cross CPU performance, given DMA-TX completion time can happen on a remote CPU. Refurbish my page_pool code, that was presented[1] at MM-summit 2016. Adapted page_pool code to not depend the page allocator and integration into struct page. The DMA mapping feature is kept, even-though it will not be activated/used in this patchset. [1] http://people.netfilter.org/hawk/presentations/MM-summit2016/generic_page_pool_mm_summit2016.pdf V2: Adjustments requested by Tariq - Changed page_pool_create return codes, don't return NULL, only ERR_PTR, as this simplifies err handling in drivers. V4: many small improvements and cleanups - Add DOC comment section, that can be used by kernel-doc - Improve fallback mode, to work better with refcnt based recycling e.g. remove a WARN as pointed out by Tariq e.g. quicker fallback if ptr_ring is empty. V5: Fixed SPDX license as pointed out by Alexei V6: Adjustments requested by Eric Dumazet - Adjust ____cacheline_aligned_in_smp usage/placement - Move rcu_head in struct page_pool - Free pages quicker on destroy, minimize resources delayed an RCU period - Remove code for forward/backward compat ABI interface V8: Issues found by kbuild test robot - Address sparse should be static warnings - Only compile+link when a driver use/select page_pool, mlx5 selects CONFIG_PAGE_POOL, although its first used in two patches Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2018-04-17 14:46:17 +00:00
/* 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_destroy_rcu(struct rcu_head *rcu)
{
struct page_pool *pool;
pool = container_of(rcu, struct page_pool, rcu);
WARN(pool->alloc.count, "API usage violation");
__page_pool_empty_ring(pool);
ptr_ring_cleanup(&pool->ring, NULL);
kfree(pool);
}
/* Cleanup and release resources */
void page_pool_destroy(struct page_pool *pool)
{
struct page *page;
/* 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);
}
/* No more consumers should exist, but producers could still
* be in-flight.
*/
__page_pool_empty_ring(pool);
/* An xdp_mem_allocator can still ref page_pool pointer */
call_rcu(&pool->rcu, __page_pool_destroy_rcu);
}
EXPORT_SYMBOL(page_pool_destroy);