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Tue, 12 Dec 2023 17:51:42 -0800 (PST) MIME-Version: 1.0 References: <20231212044614.42733-1-liangchen.linux@gmail.com> <20231212044614.42733-3-liangchen.linux@gmail.com> In-Reply-To: <20231212044614.42733-3-liangchen.linux@gmail.com> From: Mina Almasry Date: Tue, 12 Dec 2023 17:51:30 -0800 Message-ID: Subject: Re: [PATCH net-next v9 2/4] page_pool: halve BIAS_MAX for multiple user references of a fragment To: Liang Chen Cc: davem@davemloft.net, edumazet@google.com, kuba@kernel.org, pabeni@redhat.com, hawk@kernel.org, ilias.apalodimas@linaro.org, linyunsheng@huawei.com, netdev@vger.kernel.org, linux-mm@kvack.org, jasowang@redhat.com Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Rspamd-Queue-Id: 19EA98000D X-Rspam-User: X-Stat-Signature: ioad84qskrwkbp4rae51j85xpqjkyoz1 X-Rspamd-Server: rspam03 X-HE-Tag: 1702432303-17769 X-HE-Meta: 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 Y4O3U3Du 2mp1gZb9uxnoyAQ37g17peHHVmNL73D/BmnU12tInqj4bJBb+d98TJQqaWDXu0Gdcxx7TEKrtpIE5GtesOE/Q7cr0Dg9j6/LR0HMXzvobLxbYVbqVl2lftMCtvWw49y1kc8t3koHXHGE3+BoPFQkZOXU0FEA8eZRKrWhqaMcNTP7dV3qAuH/Ho0il4nv1OSbqB+5FaupS9SoBdcXq6tqNx1urlBPc5bIWO5uZXSSh3F/68JeLNFSOwGfseDSs+a7fhqN0ZcKulrmIGnBZ2EO3rQvTqYt5wSp8e9vNfHAlNLEdqbeSJrIMrRoQfEYsZm4xfO6Ye6zVwFOplbP+ENTS51aUcY7COPSEzOqKbUYJLUZvrd31B1Za5cYTfx4Uk+FPk74RH7uOv3goH9j3BwktP9lIDihYXB+31Va10fgAx5UlRcTVkbl0fnfRRZloE796qi9jOfeeRJBLBDsDRRnCAGynlQ== X-Bogosity: Ham, tests=bogofilter, spamicity=0.000101, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Mon, Dec 11, 2023 at 8:47=E2=80=AFPM Liang Chen wrote: > > Referring to patch [1], in order to support multiple users referencing th= e > 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 increme= nt > 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 Reviewed-by: Mina Almasry > --- > 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 */ > -- > 2.31.1 > > --=20 Thanks, Mina