From patchwork Fri Nov 24 07:34:37 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Liang Chen X-Patchwork-Id: 13467090 X-Patchwork-Delegate: kuba@kernel.org Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="lDFqTXps" Received: from mail-pl1-x62f.google.com (mail-pl1-x62f.google.com [IPv6:2607:f8b0:4864:20::62f]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id E5827D6E for ; Thu, 23 Nov 2023 23:35:20 -0800 (PST) Received: by mail-pl1-x62f.google.com with SMTP id d9443c01a7336-1cf5901b4c8so13631525ad.1 for ; Thu, 23 Nov 2023 23:35:20 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1700811320; x=1701416120; darn=vger.kernel.org; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:from:to:cc:subject:date :message-id:reply-to; bh=GVyM+zZxeeVgQmF9kYV8H8JgVavZaWVSN/+0EvaihZw=; b=lDFqTXps/9569pEILALOlw9RdiCVtLOOXCuM9l3kMA5Iex2iQoljxIste/YGTJpOZM 11AVVXEK/vfSLCcTlGd5tRrasR/+8X16+0K+lxqPbHhQfsZaseC99HOC6WNOYujsmmaF 2ApB/QOm6VurS77eX3f8/t7tCIbFIepijd0szBlFPN/E/5UQdwLz1hzUMHyK0CqdwmdP MsSrIEYjM9sNyj1IvgLWG71WcsjkEE6YRXT1dypr6+oHvafSSB9bu1fRK9dFMwgwBtDF BWqDGuP1XhCU2BTjAeihR4RMOdSQf1rcozm3eINH/IP8gQTuklPNKPFlxZ0O0wt1/6NP 7mfA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1700811320; x=1701416120; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=GVyM+zZxeeVgQmF9kYV8H8JgVavZaWVSN/+0EvaihZw=; b=kj2EBVGZ/GxExFQbHzQOI05bbqeBHPtA7ndSJqe9jInabVIy5Wo9Mgn/9qwtSaeC3z sOIZQbubZxD9Dp5uJIlKUZwXuonL2Um7Wst8gK8jB86cv6SUhoxLx7kK9gG35wvkBXOp hHjUi1on4iGrtqlJ/Ks/PD8oRp3MFdr/9lUm6l0PI3ee//rxCP4HWrHWjVyepVnb/bOZ TR/AXYBo+oV26FXeApyih4JJJFr7GN9Kdbq7EUt1pjBdpd1veIVFevXAcLho443aqm69 G5qUqQvz6FikUje4yWssxuhZVSVL/+7AdqLDiyDt+1coHvPIKYNCY4nRbEKSa0/lCkdy HPfw== X-Gm-Message-State: AOJu0YyJ4mYaF0SvPavsfN02UVoE6E3poSJa5iiSjMnOkJ9vGguuuyhL +DRDPhysqh3IiZBdNQFywgM= X-Google-Smtp-Source: AGHT+IFW9OW4Chd+eMwjSDquqBSaDDcPEXnyhJCyPdt6UaUVM+1Bexyln3V36mIMM6we2HvXDXpbGQ== X-Received: by 2002:a17:902:f60a:b0:1ce:6669:3260 with SMTP id n10-20020a170902f60a00b001ce66693260mr2718379plg.67.1700811320395; Thu, 23 Nov 2023 23:35:20 -0800 (PST) Received: from localhost.localdomain ([89.187.161.180]) by smtp.gmail.com with ESMTPSA id t15-20020a170902e84f00b001b9d7c8f44dsm2499329plg.182.2023.11.23.23.35.15 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 23 Nov 2023 23:35:19 -0800 (PST) From: Liang Chen To: davem@davemloft.net, edumazet@google.com, kuba@kernel.org, pabeni@redhat.com, hawk@kernel.org, ilias.apalodimas@linaro.org, linyunsheng@huawei.com Cc: netdev@vger.kernel.org, linux-mm@kvack.org, liangchen.linux@gmail.com Subject: [PATCH net-next v3 1/3] page_pool: Rename pp_frag_count to pp_ref_count Date: Fri, 24 Nov 2023 15:34:37 +0800 Message-Id: <20231124073439.52626-2-liangchen.linux@gmail.com> X-Mailer: git-send-email 2.31.1 In-Reply-To: <20231124073439.52626-1-liangchen.linux@gmail.com> References: <20231124073439.52626-1-liangchen.linux@gmail.com> Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Patchwork-Delegate: kuba@kernel.org To support multiple users referencing the same fragment, pp_frag_count is renamed to pp_ref_count to better reflect its actual meaning based on the suggestion from [1]. [1] http://lore.kernel.org/netdev/f71d9448-70c8-8793-dc9a-0eb48a570300@huawei.com Signed-off-by: Liang Chen --- .../net/ethernet/mellanox/mlx5/core/en_rx.c | 4 +- include/linux/mm_types.h | 2 +- include/net/page_pool/helpers.h | 45 ++++++++++--------- include/net/page_pool/types.h | 2 +- net/core/page_pool.c | 12 ++--- 5 files changed, 35 insertions(+), 30 deletions(-) diff --git a/drivers/net/ethernet/mellanox/mlx5/core/en_rx.c b/drivers/net/ethernet/mellanox/mlx5/core/en_rx.c index 8d9743a5e42c..4454c750733e 100644 --- a/drivers/net/ethernet/mellanox/mlx5/core/en_rx.c +++ b/drivers/net/ethernet/mellanox/mlx5/core/en_rx.c @@ -298,8 +298,8 @@ static void mlx5e_page_release_fragmented(struct mlx5e_rq *rq, u16 drain_count = MLX5E_PAGECNT_BIAS_MAX - frag_page->frags; struct page *page = frag_page->page; - if (page_pool_defrag_page(page, drain_count) == 0) - page_pool_put_defragged_page(rq->page_pool, page, -1, true); + if (page_pool_deref_page(page, drain_count) == 0) + page_pool_put_derefed_page(rq->page_pool, page, -1, true); } static inline int mlx5e_get_rx_frag(struct mlx5e_rq *rq, diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h index 957ce38768b2..64e4572ef06d 100644 --- a/include/linux/mm_types.h +++ b/include/linux/mm_types.h @@ -125,7 +125,7 @@ struct page { struct page_pool *pp; unsigned long _pp_mapping_pad; unsigned long dma_addr; - atomic_long_t pp_frag_count; + atomic_long_t pp_ref_count; }; struct { /* Tail pages of compound page */ unsigned long compound_head; /* Bit zero is set */ diff --git a/include/net/page_pool/helpers.h b/include/net/page_pool/helpers.h index 4ebd544ae977..700f435292e7 100644 --- a/include/net/page_pool/helpers.h +++ b/include/net/page_pool/helpers.h @@ -29,7 +29,7 @@ * page allocated from page pool. Page splitting enables memory saving and thus * avoids TLB/cache miss for data access, but there also is some cost to * implement page splitting, mainly some cache line dirtying/bouncing for - * 'struct page' and atomic operation for page->pp_frag_count. + * 'struct page' and atomic operation for page->pp_ref_count. * * The API keeps track of in-flight pages, in order to let API users know when * it is safe to free a page_pool object, the API users must call @@ -214,69 +214,74 @@ inline enum dma_data_direction page_pool_get_dma_dir(struct page_pool *pool) return pool->p.dma_dir; } -/* pp_frag_count represents the number of writers who can update the page +/* pp_ref_count represents the number of writers who can update the page * either by updating skb->data or via DMA mappings for the device. * We can't rely on the page refcnt for that as we don't know who might be * holding page references and we can't reliably destroy or sync DMA mappings * of the fragments. * - * When pp_frag_count reaches 0 we can either recycle the page if the page + * pp_ref_count initially corresponds to the number of fragments. However, + * when multiple users start to reference a single fragment, for example in + * skb_try_coalesce, the pp_ref_count will become greater than the number of + * fragments. + * + * When pp_ref_count reaches 0 we can either recycle the page if the page * refcnt is 1 or return it back to the memory allocator and destroy any * mappings we have. */ static inline void page_pool_fragment_page(struct page *page, long nr) { - atomic_long_set(&page->pp_frag_count, nr); + atomic_long_set(&page->pp_ref_count, nr); } -static inline long page_pool_defrag_page(struct page *page, long nr) +static inline long page_pool_deref_page(struct page *page, long nr) { long ret; - /* If nr == pp_frag_count then we have cleared all remaining + /* If nr == pp_ref_count then we have cleared all remaining * references to the page: * 1. 'n == 1': no need to actually overwrite it. * 2. 'n != 1': overwrite it with one, which is the rare case - * for pp_frag_count draining. + * for pp_ref_count draining. * * The main advantage to doing this is that not only we avoid a atomic * update, as an atomic_read is generally a much cheaper operation than * an atomic update, especially when dealing with a page that may be - * partitioned into only 2 or 3 pieces; but also unify the pp_frag_count + * referenced by only 2 or 3 users; but also unify the pp_ref_count * handling by ensuring all pages have partitioned into only 1 piece * initially, and only overwrite it when the page is partitioned into * more than one piece. */ - if (atomic_long_read(&page->pp_frag_count) == nr) { + if (atomic_long_read(&page->pp_ref_count) == nr) { /* As we have ensured nr is always one for constant case using * the BUILD_BUG_ON(), only need to handle the non-constant case - * here for pp_frag_count draining, which is a rare case. + * here for pp_ref_count draining, which is a rare case. */ BUILD_BUG_ON(__builtin_constant_p(nr) && nr != 1); if (!__builtin_constant_p(nr)) - atomic_long_set(&page->pp_frag_count, 1); + atomic_long_set(&page->pp_ref_count, 1); return 0; } - ret = atomic_long_sub_return(nr, &page->pp_frag_count); + ret = atomic_long_sub_return(nr, &page->pp_ref_count); WARN_ON(ret < 0); - /* We are the last user here too, reset pp_frag_count back to 1 to + /* We are the last user here too, reset pp_ref_count back to 1 to * ensure all pages have been partitioned into 1 piece initially, * this should be the rare case when the last two fragment users call - * page_pool_defrag_page() currently. + * page_pool_deref_page() currently. */ if (unlikely(!ret)) - atomic_long_set(&page->pp_frag_count, 1); + atomic_long_set(&page->pp_ref_count, 1); return ret; } -static inline bool page_pool_is_last_frag(struct page *page) +static inline bool page_pool_is_last_ref(struct page *page) { - /* If page_pool_defrag_page() returns 0, we were the last user */ - return page_pool_defrag_page(page, 1) == 0; + /* If page_pool_deref_page() returns 0, we were the last user */ + return page_pool_deref_page(page, 1) == 0; } /** @@ -301,10 +306,10 @@ static inline void page_pool_put_page(struct page_pool *pool, * allow registering MEM_TYPE_PAGE_POOL, but shield linker. */ #ifdef CONFIG_PAGE_POOL - if (!page_pool_is_last_frag(page)) + if (!page_pool_is_last_ref(page)) return; - page_pool_put_defragged_page(pool, page, dma_sync_size, allow_direct); + page_pool_put_derefed_page(pool, page, dma_sync_size, allow_direct); #endif } diff --git a/include/net/page_pool/types.h b/include/net/page_pool/types.h index e1bb92c192de..1c82e87f2577 100644 --- a/include/net/page_pool/types.h +++ b/include/net/page_pool/types.h @@ -224,7 +224,7 @@ static inline void page_pool_put_page_bulk(struct page_pool *pool, void **data, } #endif -void page_pool_put_defragged_page(struct page_pool *pool, struct page *page, +void page_pool_put_derefed_page(struct page_pool *pool, struct page *page, unsigned int dma_sync_size, bool allow_direct); diff --git a/net/core/page_pool.c b/net/core/page_pool.c index df2a06d7da52..0c6c2b11aabe 100644 --- a/net/core/page_pool.c +++ b/net/core/page_pool.c @@ -650,8 +650,8 @@ __page_pool_put_page(struct page_pool *pool, struct page *page, return NULL; } -void page_pool_put_defragged_page(struct page_pool *pool, struct page *page, - unsigned int dma_sync_size, bool allow_direct) +void page_pool_put_derefed_page(struct page_pool *pool, struct page *page, + unsigned int dma_sync_size, bool allow_direct) { page = __page_pool_put_page(pool, page, dma_sync_size, allow_direct); if (page && !page_pool_recycle_in_ring(pool, page)) { @@ -660,7 +660,7 @@ void page_pool_put_defragged_page(struct page_pool *pool, struct page *page, page_pool_return_page(pool, page); } } -EXPORT_SYMBOL(page_pool_put_defragged_page); +EXPORT_SYMBOL(page_pool_put_derefed_page); /** * page_pool_put_page_bulk() - release references on multiple pages @@ -687,7 +687,7 @@ void page_pool_put_page_bulk(struct page_pool *pool, void **data, struct page *page = virt_to_head_page(data[i]); /* It is not the last user for the page frag case */ - if (!page_pool_is_last_frag(page)) + if (!page_pool_is_last_ref(page)) continue; page = __page_pool_put_page(pool, page, -1, false); @@ -729,7 +729,7 @@ static struct page *page_pool_drain_frag(struct page_pool *pool, long drain_count = BIAS_MAX - pool->frag_users; /* Some user is still using the page frag */ - if (likely(page_pool_defrag_page(page, drain_count))) + if (likely(page_pool_deref_page(page, drain_count))) return NULL; if (page_ref_count(page) == 1 && !page_is_pfmemalloc(page)) { @@ -750,7 +750,7 @@ static void page_pool_free_frag(struct page_pool *pool) pool->frag_page = NULL; - if (!page || page_pool_defrag_page(page, drain_count)) + if (!page || page_pool_deref_page(page, drain_count)) return; page_pool_return_page(pool, page); From patchwork Fri Nov 24 07:34:38 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Liang Chen X-Patchwork-Id: 13467091 X-Patchwork-Delegate: kuba@kernel.org Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="LA8rtDH5" Received: from mail-pj1-x102a.google.com (mail-pj1-x102a.google.com [IPv6:2607:f8b0:4864:20::102a]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id B94F7D4E for ; 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[1] https://lore.kernel.org/all/20211009093724.10539-3-linyunsheng@huawei.com/ Signed-off-by: Liang Chen Reviewed-by: Yunsheng Lin --- net/core/page_pool.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/net/core/page_pool.c b/net/core/page_pool.c index 0c6c2b11aabe..24b83dfe6968 100644 --- a/net/core/page_pool.c +++ b/net/core/page_pool.c @@ -26,7 +26,7 @@ #define DEFER_TIME (msecs_to_jiffies(1000)) #define DEFER_WARN_INTERVAL (60 * HZ) -#define BIAS_MAX LONG_MAX +#define BIAS_MAX (LONG_MAX >> 1) #ifdef CONFIG_PAGE_POOL_STATS /* alloc_stat_inc is intended to be used in softirq context */ From patchwork Fri Nov 24 07:34:39 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Liang Chen X-Patchwork-Id: 13467092 X-Patchwork-Delegate: kuba@kernel.org Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="MpwqE16e" Received: from mail-pg1-x531.google.com (mail-pg1-x531.google.com [IPv6:2607:f8b0:4864:20::531]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id A90F1D5E for ; Thu, 23 Nov 2023 23:35:32 -0800 (PST) Received: by mail-pg1-x531.google.com with SMTP id 41be03b00d2f7-5c1f8b0c149so1076637a12.3 for ; Thu, 23 Nov 2023 23:35:32 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1700811332; x=1701416132; darn=vger.kernel.org; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:from:to:cc:subject:date :message-id:reply-to; bh=1+7Fm45mXPbJos9JDi9Ng8q2lxxttPsawkbzBvsMyCY=; b=MpwqE16enhOkb0XEosc2bPe0hEAWGc5m0cLwv17+7xgQ6Dyx+xUa9stL89swSx5qCX Ef5pQdqxNHUOw0qAXYN8R1jZv6z5GM70ADAgYMKdg77uXs/b0LFE8DHbltvoVb6EEQc5 KcruNb7rWatWqjzpyekavZqaYaiAF1UfNLN7fvUfuxjAkOXjtDEzjPDKJw7CD4Bmelqb wZPEjicq5SfVaoWFaZTPlsBeXHOQxXfmBdqyGn51o82hPQ37mIYecmk94HRGXftuZqXD ODbbgpqs2DxFw4MPTQXVdkrvSU32kusCs2w0/HKNfuUiKn2xfsmAfi+jLmXYuDWSxBi0 FtcQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1700811332; x=1701416132; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=1+7Fm45mXPbJos9JDi9Ng8q2lxxttPsawkbzBvsMyCY=; b=P1OgASPLjer34w7cBVZDsrt+YdcQUHFAmUOm6GDgkxsul0rMNQNSZxKr5iMlPvBCxa W5KCN5NEsyoEheHJXFZ1c9glK+VioOwokmV4ZtlrxkbnEPaefabEQVEIfufHMR4c89Ry D0ia5LrctOEwHN7LKutgvl6ThDAdAmTtrChZZ+GGUnE6CC1mECGbTUc5RIXIyTR8SML4 epD+o7ZDlnfzaGp/kzzGlVSgrDxWJOlXFs3/kGWgd5n5JXYFNJmWYo8ntwEGio5zkq6P V4itK9DXw/ixKzz+qDUdeGL1XJL+HAbC1cKeoO+mbbVsPsNesRFA7srJyhnm0kTL87VF TrfQ== X-Gm-Message-State: AOJu0YyVYiEfy/6zqIDneQM9doHZsoOj+R25G5/lCH/l/xq5A0uM582s oTCNRgJm93VQeDV3eQXXFu4= X-Google-Smtp-Source: AGHT+IEY5zFaHsjjsH+W05ik6A5APVeYSGIO3q3AFeGd/v8kdg+F0wdCUU5FPt/FldayEbptAC3s9w== X-Received: by 2002:a05:6a20:4388:b0:18b:30d1:8140 with SMTP id i8-20020a056a20438800b0018b30d18140mr2442174pzl.6.1700811331713; Thu, 23 Nov 2023 23:35:31 -0800 (PST) Received: from localhost.localdomain ([89.187.161.180]) by smtp.gmail.com with ESMTPSA id t15-20020a170902e84f00b001b9d7c8f44dsm2499329plg.182.2023.11.23.23.35.26 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 23 Nov 2023 23:35:30 -0800 (PST) From: Liang Chen To: davem@davemloft.net, edumazet@google.com, kuba@kernel.org, pabeni@redhat.com, hawk@kernel.org, ilias.apalodimas@linaro.org, linyunsheng@huawei.com Cc: netdev@vger.kernel.org, linux-mm@kvack.org, liangchen.linux@gmail.com Subject: [PATCH net-next v3 3/3] skbuff: Optimization of SKB coalescing for page pool Date: Fri, 24 Nov 2023 15:34:39 +0800 Message-Id: <20231124073439.52626-4-liangchen.linux@gmail.com> X-Mailer: git-send-email 2.31.1 In-Reply-To: <20231124073439.52626-1-liangchen.linux@gmail.com> References: <20231124073439.52626-1-liangchen.linux@gmail.com> Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Patchwork-Delegate: kuba@kernel.org In order to address the issues encountered with commit 1effe8ca4e34 ("skbuff: fix coalescing for page_pool fragment recycling"), the combination of the following condition was excluded from skb coalescing: from->pp_recycle = 1 from->cloned = 1 to->pp_recycle = 1 However, with page pool environments, the aforementioned combination can be quite common(ex. NetworkMananger may lead to the additional packet_type being registered, thus the cloning). In scenarios with a higher number of small packets, it can significantly affect the success rate of coalescing. For example, considering packets of 256 bytes size, our comparison of coalescing success rate is as follows: Without page pool: 70% With page pool: 13% Consequently, this has an impact on performance: Without page pool: 2.57 Gbits/sec With page pool: 2.26 Gbits/sec Therefore, it seems worthwhile to optimize this scenario and enable coalescing of this particular combination. To achieve this, we need to ensure the correct increment of the "from" SKB page's page pool reference count (pp_ref_count). Following this optimization, the success rate of coalescing measured in our environment has improved as follows: With page pool: 60% This success rate is approaching the rate achieved without using page pool, and the performance has also been improved: With page pool: 2.52 Gbits/sec Below is the performance comparison for small packets before and after this optimization. We observe no impact to packets larger than 4K. packet size before after improved (bytes) (Gbits/sec) (Gbits/sec) 128 1.19 1.27 7.13% 256 2.26 2.52 11.75% 512 4.13 4.81 16.50% 1024 6.17 6.73 9.05% 2048 14.54 15.47 6.45% 4096 25.44 27.87 9.52% Signed-off-by: Liang Chen --- include/net/page_pool/helpers.h | 22 ++++++++++++++++++++++ net/core/skbuff.c | 23 +++++++++++------------ 2 files changed, 33 insertions(+), 12 deletions(-) diff --git a/include/net/page_pool/helpers.h b/include/net/page_pool/helpers.h index 700f435292e7..6b3c0d4d47f5 100644 --- a/include/net/page_pool/helpers.h +++ b/include/net/page_pool/helpers.h @@ -402,4 +402,26 @@ static inline void page_pool_nid_changed(struct page_pool *pool, int new_nid) page_pool_update_nid(pool, new_nid); } +static inline bool page_pool_is_pp_page(struct page *page) +{ + return (page->pp_magic & ~0x3UL) == PP_SIGNATURE; +} + +/** + * page_pool_get_frag_ref() - Increase fragment reference count of a page + * @page: page of the fragment on which to increase a reference + * + * Increase fragment reference count (pp_ref_count) on a page, but if it is + * not a page pool page, fallback to increase a reference(_refcount) on a + * normal page. + */ +static inline void page_pool_get_frag_ref(struct page *page) +{ + struct page *head_page = compound_head(page); + + if (likely(page_pool_is_pp_page(head_page))) + atomic_long_inc(&head_page->pp_ref_count); + else + get_page(head_page); +} #endif /* _NET_PAGE_POOL_HELPERS_H */ diff --git a/net/core/skbuff.c b/net/core/skbuff.c index b157efea5dea..54e6945ead56 100644 --- a/net/core/skbuff.c +++ b/net/core/skbuff.c @@ -5764,17 +5764,12 @@ bool skb_try_coalesce(struct sk_buff *to, struct sk_buff *from, return false; /* In general, avoid mixing page_pool and non-page_pool allocated - * pages within the same SKB. Additionally avoid dealing with clones - * with page_pool pages, in case the SKB is using page_pool fragment - * references (page_pool_alloc_frag()). Since we only take full page - * references for cloned SKBs at the moment that would result in - * inconsistent reference counts. - * In theory we could take full references if @from is cloned and - * !@to->pp_recycle but its tricky (due to potential race with - * the clone disappearing) and rare, so not worth dealing with. + * pages within the same SKB. In theory we could take full + * references if @from is cloned and !@to->pp_recycle but its + * tricky (due to potential race with the clone disappearing) and + * rare, so not worth dealing with. */ - if (to->pp_recycle != from->pp_recycle || - (from->pp_recycle && skb_cloned(from))) + if (to->pp_recycle != from->pp_recycle) return false; if (len <= skb_tailroom(to)) { @@ -5831,8 +5826,12 @@ bool skb_try_coalesce(struct sk_buff *to, struct sk_buff *from, /* if the skb is not cloned this does nothing * since we set nr_frags to 0. */ - for (i = 0; i < from_shinfo->nr_frags; i++) - __skb_frag_ref(&from_shinfo->frags[i]); + if (from->pp_recycle) + for (i = 0; i < from_shinfo->nr_frags; i++) + page_pool_get_frag_ref(skb_frag_page(&from_shinfo->frags[i])); + else + for (i = 0; i < from_shinfo->nr_frags; i++) + __skb_frag_ref(&from_shinfo->frags[i]); to->truesize += delta; to->len += len;