page_pool: refill page when alloc.count of pool is zero (304db6cb) · Commits · 戴 / test

"do {} while" in page_pool_refill_alloc_cache will always refill page once whether refill is true or false, and whether alloc.count of pool is less than PP_ALLOC_CACHE_REFILL or not this is wrong, and will cause overflow of pool->alloc.cache the caller of __page_pool_get_cached should provide guarantee that pool->alloc.cache is safe to access, so in_serving_softirq should be removed as suggested by Jesper Dangaard Brouer in https://patchwork.ozlabs.org/patch/1233713/ so fix this issue by calling page_pool_refill_alloc_cache() only when pool->alloc.count is zero Fixes: ("page_pool: handle page recycle for NUMA_NO_NODE condition") Signed-off-by:

Li RongQing <lirongqing@baidu.com> Suggested-by:

Jesper Dangaard Brouer <brouer@redhat.com> Acked-by:

Ilias Apalodimas <ilias.apalodimas@linaro.org> Signed-off-by:

David S. Miller <davem@davemloft.net>

net/core/page_pool.c

+8 −14

Original line number	Diff line number	Diff line
		@@ -99,8 +99,7 @@ EXPORT_SYMBOL(page_pool_create);
		static void __page_pool_return_page(struct page_pool pool, struct page page);

		noinline
		static struct page page_pool_refill_alloc_cache(struct page_pool pool,
		bool refill)
		static struct page page_pool_refill_alloc_cache(struct page_pool pool)
		{
		struct ptr_ring *r = &pool->ring;
		struct page *page;
		@@ -141,8 +140,7 @@ static struct page page_pool_refill_alloc_cache(struct page_pool pool,
		page = NULL;
		break;
		}
		} while (pool->alloc.count < PP_ALLOC_CACHE_REFILL &&
		refill);
		} while (pool->alloc.count < PP_ALLOC_CACHE_REFILL);

		/* Return last page */
		if (likely(pool->alloc.count > 0))
		@@ -155,20 +153,16 @@ static struct page page_pool_refill_alloc_cache(struct page_pool pool,
		/* fast path */
		static struct page __page_pool_get_cached(struct page_pool pool)
		{
		bool refill = false;
		struct page *page;

		/* Test for safe-context, caller should provide this guarantee */
		if (likely(in_serving_softirq())) {
		/* Caller MUST guarantee safe non-concurrent access, e.g. softirq */
		if (likely(pool->alloc.count)) {
		/* Fast-path */
		page = pool->alloc.cache[--pool->alloc.count];
		return page;
		}
		refill = true;
		} else {
		page = page_pool_refill_alloc_cache(pool);
		}

		page = page_pool_refill_alloc_cache(pool, refill);
		return page;
		}

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