From: Yunsheng Lin <linyunsheng@huawei.com>
To: Ilias Apalodimas <ilias.apalodimas@linaro.org>
Cc: <davem@davemloft.net>, <kuba@kernel.org>,
<netdev@vger.kernel.org>, <linux-kernel@vger.kernel.org>,
<linuxarm@openeuler.org>, <hawk@kernel.org>,
<jonathan.lemon@gmail.com>, <alobakin@pm.me>,
<willemb@google.com>, <cong.wang@bytedance.com>,
<pabeni@redhat.com>, <haokexin@gmail.com>, <nogikh@google.com>,
<elver@google.com>, <memxor@gmail.com>, <edumazet@google.com>,
<alexander.duyck@gmail.com>, <dsahern@gmail.com>
Subject: Re: [PATCH net-next 3/7] pool_pool: avoid calling compound_head() for skb frag page
Date: Thu, 23 Sep 2021 19:24:24 +0800 [thread overview]
Message-ID: <b2779d81-4cb3-5ccc-8e36-02cd633383f3@huawei.com> (raw)
In-Reply-To: <YUw78q4IrfR0D2/J@apalos.home>
On 2021/9/23 16:33, Ilias Apalodimas wrote:
> On Wed, Sep 22, 2021 at 05:41:27PM +0800, Yunsheng Lin wrote:
>> As the pp page for a skb frag is always a head page, so make
>> sure skb_pp_recycle() passes a head page to avoid calling
>> compound_head() for skb frag page case.
>
> Doesn't that rely on the driver mostly (i.e what's passed in skb_frag_set_page() ?
> None of the current netstack code assumes bv_page is the head page of a
> compound page. Since our page_pool allocator can will allocate compound
> pages for order > 0, why should we rely on it ?
As the page pool alloc function return 'struct page *' to the caller, which
is the head page of a compound pages for order > 0, so I assume the caller
will pass that to skb_frag_set_page().
For non-pp page, I assume it is ok whether the page is a head page or tail
page, as the pp_magic for both of them are not set with PP_SIGNATURE.
Or should we play safe here, and do the trick as skb_free_head() does in
patch 6?
>
> Thanks
> /Ilias
>>
>> Signed-off-by: Yunsheng Lin <linyunsheng@huawei.com>
>> ---
>> include/linux/skbuff.h | 2 +-
>> net/core/page_pool.c | 2 --
>> 2 files changed, 1 insertion(+), 3 deletions(-)
>>
>> diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
>> index 6bdb0db3e825..35eebc2310a5 100644
>> --- a/include/linux/skbuff.h
>> +++ b/include/linux/skbuff.h
>> @@ -4722,7 +4722,7 @@ static inline bool skb_pp_recycle(struct sk_buff *skb, void *data)
>> {
>> if (!IS_ENABLED(CONFIG_PAGE_POOL) || !skb->pp_recycle)
>> return false;
>> - return page_pool_return_skb_page(virt_to_page(data));
>> + return page_pool_return_skb_page(virt_to_head_page(data));
>> }
>>
>> #endif /* __KERNEL__ */
>> diff --git a/net/core/page_pool.c b/net/core/page_pool.c
>> index f7e71dcb6a2e..357fb53343a0 100644
>> --- a/net/core/page_pool.c
>> +++ b/net/core/page_pool.c
>> @@ -742,8 +742,6 @@ bool page_pool_return_skb_page(struct page *page)
>> {
>> struct page_pool *pp;
>>
>> - page = compound_head(page);
>> -
>> /* page->pp_magic is OR'ed with PP_SIGNATURE after the allocation
>> * in order to preserve any existing bits, such as bit 0 for the
>> * head page of compound page and bit 1 for pfmemalloc page, so
>> --
>> 2.33.0
>>
> .
>
next prev parent reply other threads:[~2021-09-23 11:24 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-09-22 9:41 [PATCH net-next 0/7] some optimization for page pool Yunsheng Lin
2021-09-22 9:41 ` [PATCH net-next 1/7] page_pool: disable dma mapping support for 32-bit arch with 64-bit DMA Yunsheng Lin
2021-09-23 9:10 ` Ilias Apalodimas
2021-09-23 9:33 ` Jesper Dangaard Brouer
2021-09-23 10:02 ` Ilias Apalodimas
2021-09-23 11:13 ` Yunsheng Lin
2021-09-23 13:07 ` Ilias Apalodimas
2021-09-24 7:04 ` Yunsheng Lin
2021-09-24 7:25 ` Ilias Apalodimas
2021-09-24 8:01 ` Yunsheng Lin
2021-09-22 9:41 ` [PATCH net-next 2/7] page_pool: support non-split page with PP_FLAG_PAGE_FRAG Yunsheng Lin
2021-09-23 12:08 ` Jesper Dangaard Brouer
2021-09-24 7:23 ` Yunsheng Lin
2021-09-30 7:28 ` [Linuxarm] " Yunsheng Lin
2021-09-22 9:41 ` [PATCH net-next 3/7] pool_pool: avoid calling compound_head() for skb frag page Yunsheng Lin
2021-09-23 8:33 ` Ilias Apalodimas
2021-09-23 11:24 ` Yunsheng Lin [this message]
2021-09-23 11:47 ` Ilias Apalodimas
2021-09-24 7:33 ` Yunsheng Lin
2021-09-24 7:44 ` Ilias Apalodimas
2021-09-22 9:41 ` [PATCH net-next 4/7] page_pool: change BIAS_MAX to support incrementing Yunsheng Lin
2021-09-22 9:41 ` [PATCH net-next 5/7] skbuff: keep track of pp page when __skb_frag_ref() is called Yunsheng Lin
2021-09-22 9:41 ` [PATCH net-next 6/7] skbuff: only use pp_magic identifier for a skb' head page Yunsheng Lin
2021-09-22 9:41 ` [PATCH net-next 7/7] skbuff: remove unused skb->pp_recycle Yunsheng Lin
2021-09-23 7:07 ` [PATCH net-next 0/7] some optimization for page pool Ilias Apalodimas
2021-09-23 11:12 ` Yunsheng Lin
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