From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-9.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 373FCC352A4 for ; Tue, 11 Feb 2020 02:14:46 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 17A132072C for ; Tue, 11 Feb 2020 02:14:46 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727797AbgBKCN7 (ORCPT ); Mon, 10 Feb 2020 21:13:59 -0500 Received: from mx133-tc.baidu.com ([61.135.168.133]:20578 "EHLO tc-sys-mailedm03.tc.baidu.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1727612AbgBKCN7 (ORCPT ); Mon, 10 Feb 2020 21:13:59 -0500 Received: from localhost (cp01-cos-dev01.cp01.baidu.com [10.92.119.46]) by tc-sys-mailedm03.tc.baidu.com (Postfix) with ESMTP id 334394500032; Tue, 11 Feb 2020 10:13:44 +0800 (CST) From: Li RongQing To: netdev@vger.kernel.org, brouer@redhat.com Subject: [PATCH][v2] page_pool: refill page when alloc.count of pool is zero Date: Tue, 11 Feb 2020 10:13:44 +0800 Message-Id: <1581387224-20719-1-git-send-email-lirongqing@baidu.com> X-Mailer: git-send-email 1.7.1 Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org "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: 44768decb7c0 ("page_pool: handle page recycle for NUMA_NO_NODE condition") Signed-off-by: Li RongQing Suggested: Jesper Dangaard Brouer --- v1-->v2: remove the in_serving_softirq test net/core/page_pool.c | 22 ++++++++-------------- 1 file changed, 8 insertions(+), 14 deletions(-) diff --git a/net/core/page_pool.c b/net/core/page_pool.c index 9b7cbe35df37..10d2b255df5e 100644 --- a/net/core/page_pool.c +++ b/net/core/page_pool.c @@ -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())) { - if (likely(pool->alloc.count)) { - /* Fast-path */ - page = pool->alloc.cache[--pool->alloc.count]; - return page; - } - refill = true; + /* Caller MUST guarantee safe non-concurrent access, e.g. softirq */ + if (likely(pool->alloc.count)) { + /* Fast-path */ + page = pool->alloc.cache[--pool->alloc.count]; + } else { + page = page_pool_refill_alloc_cache(pool); } - page = page_pool_refill_alloc_cache(pool, refill); return page; } -- 2.16.2