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imf27.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20201202 header.b=ntcoumax; dmarc=pass (policy=none) header.from=kernel.org; spf=pass (imf27.hostedemail.com: domain of hawk@kernel.org designates 145.40.68.75 as permitted sender) smtp.mailfrom=hawk@kernel.org ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1702289529; a=rsa-sha256; cv=none; b=LY3O2lyt3uxcQIl739stst8ofE+gIWQCQh0coEC4Pd/xhVNNIHO8H8pyidzm4gj5DhRw5e 8tmFmt3L+wsA9TXKzsbc3oAhADFMKD/+BZqSm7l5qSJ0aGMmqIS7ChEgfpKdUAVc3OcOp4 0txAGD2akOTjjJQwqUgomPpdH90i5ME= Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by ams.source.kernel.org (Postfix) with ESMTP id D5D7BB80D64; Mon, 11 Dec 2023 10:12:07 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 02E2DC433C7; Mon, 11 Dec 2023 10:12:03 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1702289527; bh=7ZXmd5rh4Rqq/IAxc7eaZo+Bf3FwdWSw0W4uYwdYPqc=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=ntcoumaxavZrdA6pD8HO9I8uUIV8ziJTPWMNGRdwJjYSchwfy9H3CNL2ebURgN+3B R0hm53oQ01uvFLYMR8UUxe2p+tdRc8kFvfQn2MM8crnkyHeMKJuQo2gzWiw7BM3jck ke2parp67vwgAdLXklisge+oUonDNQJ05JtAxeK3rbrrxRl835/3eDCCgvtrQpN1dN Sezx3LN/WrHm1hyH8h1plqEnMHvQisygz1TIktV2Qg3mfo2QjRAW0E2rcIVy6x7E82 iOfm6FluXlUeI/74HWL+xiFzLO1XRUKn/fYxJUJ5oOerHDynszMbzXxOwebxcHLGl1 XSMI0dwCT41+Q== Message-ID: <6f7f7724-12a0-45d5-80dc-a811b58783c8@kernel.org> Date: Mon, 11 Dec 2023 11:12:01 +0100 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH net-next v8 2/4] page_pool: halve BIAS_MAX for multiple user references of a fragment To: Alexander Duyck Cc: netdev@vger.kernel.org, linux-mm@kvack.org, kuba@kernel.org, ilias.apalodimas@linaro.org, jasowang@redhat.com, linyunsheng@huawei.com, Liang Chen , edumazet@google.com, davem@davemloft.net, almasrymina@google.com, pabeni@redhat.com References: <20231211035243.15774-1-liangchen.linux@gmail.com> <20231211035243.15774-3-liangchen.linux@gmail.com> Content-Language: en-US From: Jesper Dangaard Brouer In-Reply-To: <20231211035243.15774-3-liangchen.linux@gmail.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Rspam-User: X-Stat-Signature: 9wwasq1otaq1e8dfjj33qscpmopgif1q X-Rspamd-Server: rspam07 X-Rspamd-Queue-Id: 949F840023 X-HE-Tag: 1702289529-877382 X-HE-Meta: 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 25nfsdwa fMfPhAhotgYcFaz2DnEC9+Tnwi3b5RNqpCmH321/ZqhXnUMBWxBMKV+Ev1ZrBkZoL6NW/2NICT7VDpIClUHPeojrLLKWP0vHPTjNXEsKl8h0n0qf7acWMOgMR8IBcrFbA/MT11SOXkqH2VxK0rbIKj69DTSJtudTu6ESGtgU8iqS9v+luK2kgGVkv2X4wRNIKiprJFF/LUpeH1FVelEqx2D5aqcpZlBPU3zs9MHsYfDdHUYOZa43NL1HXacC59EuGjDtLbkktJ12OWIx3ldlEaDhwDgcX1BDxjhl4+v6M8N9vGn1Iw1Zz+IGeXGzU/i2R7HxhBDCQZcICBQI3PUm39AYyvOU1Mrh4n1Gi7LrJPsVFiQWzXfZ3yLV3D1ekAF6s9umuS+cDEMkEJ5nvqujP4NKpIRnFaZpj9g7M9NDiveKMYyO+PFwydh02bMRlswmxwjDBgWVxRbde4s0= X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: Hi Alex, For page_pool BIAS stuff I would really appreciate your review please. -Jesper On 11/12/2023 04.52, Liang Chen wrote: > Referring to patch [1], in order to support multiple users referencing the > same fragment and prevent overflow from pp_ref_count growing, the initial > value of pp_ref_count is halved, leaving room for pp_ref_count to increment > before the page is drained. > > [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 106220b1f89c..436f7ffea7b4 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 */