From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from szxga05-in.huawei.com (szxga05-in.huawei.com [45.249.212.191]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id BB833C139; Mon, 8 Jan 2024 08:25:49 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=huawei.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=huawei.com Received: from mail.maildlp.com (unknown [172.19.88.234]) by szxga05-in.huawei.com (SkyGuard) with ESMTP id 4T7nCc0ZBmz1gx9K; Mon, 8 Jan 2024 16:24:12 +0800 (CST) Received: from dggpemm500005.china.huawei.com (unknown [7.185.36.74]) by mail.maildlp.com (Postfix) with ESMTPS id 07150140384; Mon, 8 Jan 2024 16:25:42 +0800 (CST) Received: from [10.69.30.204] (10.69.30.204) by dggpemm500005.china.huawei.com (7.185.36.74) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2507.35; Mon, 8 Jan 2024 16:25:41 +0800 Subject: Re: [PATCH net-next 2/6] page_frag: unify gfp bits for order 3 page allocation To: Alexander H Duyck , , , CC: , , "Michael S. Tsirkin" , Jason Wang , Andrew Morton , Eric Dumazet , , , References: <20240103095650.25769-1-linyunsheng@huawei.com> <20240103095650.25769-3-linyunsheng@huawei.com> From: Yunsheng Lin Message-ID: <1d40427d-78e3-ef40-a63f-206c0697bda2@huawei.com> Date: Mon, 8 Jan 2024 16:25:41 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:52.0) Gecko/20100101 Thunderbird/52.2.0 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset="utf-8" Content-Language: en-US Content-Transfer-Encoding: 7bit X-ClientProxiedBy: dggems703-chm.china.huawei.com (10.3.19.180) To dggpemm500005.china.huawei.com (7.185.36.74) On 2024/1/5 23:35, Alexander H Duyck wrote: > On Wed, 2024-01-03 at 17:56 +0800, Yunsheng Lin wrote: >> Currently there seems to be three page frag implementions >> which all try to allocate order 3 page, if that fails, it >> then fail back to allocate order 0 page, and each of them >> all allow order 3 page allocation to fail under certain >> condition by using specific gfp bits. >> >> The gfp bits for order 3 page allocation are different >> between different implementation, __GFP_NOMEMALLOC is >> or'd to forbid access to emergency reserves memory for >> __page_frag_cache_refill(), but it is not or'd in other >> implementions, __GFP_DIRECT_RECLAIM is masked off to avoid >> direct reclaim in skb_page_frag_refill(), but it is not >> masked off in __page_frag_cache_refill(). >> >> This patch unifies the gfp bits used between different >> implementions by or'ing __GFP_NOMEMALLOC and masking off >> __GFP_DIRECT_RECLAIM for order 3 page allocation to avoid >> possible pressure for mm. >> >> Signed-off-by: Yunsheng Lin >> CC: Alexander Duyck >> --- >> drivers/vhost/net.c | 2 +- >> mm/page_alloc.c | 4 ++-- >> net/core/sock.c | 2 +- >> 3 files changed, 4 insertions(+), 4 deletions(-) >> >> diff --git a/drivers/vhost/net.c b/drivers/vhost/net.c >> index f2ed7167c848..e574e21cc0ca 100644 >> --- a/drivers/vhost/net.c >> +++ b/drivers/vhost/net.c >> @@ -670,7 +670,7 @@ static bool vhost_net_page_frag_refill(struct vhost_net *net, unsigned int sz, >> /* Avoid direct reclaim but allow kswapd to wake */ >> pfrag->page = alloc_pages((gfp & ~__GFP_DIRECT_RECLAIM) | >> __GFP_COMP | __GFP_NOWARN | >> - __GFP_NORETRY, >> + __GFP_NORETRY | __GFP_NOMEMALLOC, >> SKB_FRAG_PAGE_ORDER); >> if (likely(pfrag->page)) { >> pfrag->size = PAGE_SIZE << SKB_FRAG_PAGE_ORDER; >> diff --git a/mm/page_alloc.c b/mm/page_alloc.c >> index 9a16305cf985..1f0b36dd81b5 100644 >> --- a/mm/page_alloc.c >> +++ b/mm/page_alloc.c >> @@ -4693,8 +4693,8 @@ static struct page *__page_frag_cache_refill(struct page_frag_cache *nc, >> gfp_t gfp = gfp_mask; >> >> #if (PAGE_SIZE < PAGE_FRAG_CACHE_MAX_SIZE) >> - gfp_mask |= __GFP_COMP | __GFP_NOWARN | __GFP_NORETRY | >> - __GFP_NOMEMALLOC; >> + gfp_mask = (gfp_mask & ~__GFP_DIRECT_RECLAIM) | __GFP_COMP | >> + __GFP_NOWARN | __GFP_NORETRY | __GFP_NOMEMALLOC; >> page = alloc_pages_node(NUMA_NO_NODE, gfp_mask, >> PAGE_FRAG_CACHE_MAX_ORDER); >> nc->size = page ? PAGE_FRAG_CACHE_MAX_SIZE : PAGE_SIZE; >> diff --git a/net/core/sock.c b/net/core/sock.c >> index 446e945f736b..d643332c3ee5 100644 >> --- a/net/core/sock.c >> +++ b/net/core/sock.c >> @@ -2900,7 +2900,7 @@ bool skb_page_frag_refill(unsigned int sz, struct page_frag *pfrag, gfp_t gfp) >> /* Avoid direct reclaim but allow kswapd to wake */ >> pfrag->page = alloc_pages((gfp & ~__GFP_DIRECT_RECLAIM) | >> __GFP_COMP | __GFP_NOWARN | >> - __GFP_NORETRY, >> + __GFP_NORETRY | __GFP_NOMEMALLOC, >> SKB_FRAG_PAGE_ORDER); >> if (likely(pfrag->page)) { >> pfrag->size = PAGE_SIZE << SKB_FRAG_PAGE_ORDER; > > Looks fine to me. > > One thing you may want to consider would be to place this all in an > inline function that could just consolidate all the code. Do you think it is possible to further unify the implementations of the 'struct page_frag_cache' and 'struct page_frag', so adding a inline function for above is unnecessary? > > Reviewed-by: Alexander Duyck > > . >