From: Jakub Kicinski <kuba@kernel.org>
To: Alexander Lobakin <aleksander.lobakin@intel.com>
Cc: "David S. Miller" <davem@davemloft.net>,
Eric Dumazet <edumazet@google.com>,
Paolo Abeni <pabeni@redhat.com>,
Maciej Fijalkowski <maciej.fijalkowski@intel.com>,
Larysa Zaremba <larysa.zaremba@intel.com>,
Yunsheng Lin <linyunsheng@huawei.com>,
Alexander Duyck <alexanderduyck@fb.com>,
Jesper Dangaard Brouer <hawk@kernel.org>,
"Ilias Apalodimas" <ilias.apalodimas@linaro.org>,
<netdev@vger.kernel.org>, <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH RFC net-next v2 7/7] net: skbuff: always try to recycle PP pages directly when in softirq
Date: Wed, 19 Jul 2023 13:51:50 -0700 [thread overview]
Message-ID: <20230719135150.4da2f0ff@kernel.org> (raw)
In-Reply-To: <d7cd1903-de0e-0fe3-eb15-0146b589c7b0@intel.com>
On Wed, 19 Jul 2023 18:34:46 +0200 Alexander Lobakin wrote:
> > What if we got here from netpoll? napi budget was 0, so napi_safe is
> > false, but in_softirq() can be true or false.
>
> If we're on the same CPU where the NAPI would run and in the same
> context, i.e. softirq, in which the NAPI would run, what is the problem?
> If there really is a good one, I can handle it here.
#define SOFTIRQ_BITS 8
#define SOFTIRQ_MASK (__IRQ_MASK(SOFTIRQ_BITS) << SOFTIRQ_SHIFT)
# define softirq_count() (preempt_count() & SOFTIRQ_MASK)
#define in_softirq() (softirq_count())
I don't know what else to add beyond that and the earlier explanation.
AFAIK pages as allocated by page pool do not benefit from the usual
KASAN / KMSAN checkers, so if we were to double-recycle a page once
a day because of a netcons race - it's going to be a month long debug
for those of us using Linux in production.
next prev parent reply other threads:[~2023-07-19 20:51 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-07-14 17:08 [PATCH RFC net-next v2 0/7] net: page_pool: a couple of assorted optimizations Alexander Lobakin
2023-07-14 17:08 ` [PATCH RFC net-next v2 1/7] net: skbuff: don't include <net/page_pool.h> to <linux/skbuff.h> Alexander Lobakin
2023-07-14 17:08 ` [PATCH RFC net-next v2 2/7] net: page_pool: place frag_* fields in one cacheline Alexander Lobakin
2023-07-14 17:14 ` Alexander Lobakin
2023-07-14 18:37 ` Jesper Dangaard Brouer
2023-07-18 13:50 ` Alexander Lobakin
2023-07-26 8:13 ` Ilias Apalodimas
2023-07-26 10:39 ` Alexander Lobakin
2023-07-14 17:08 ` [PATCH RFC net-next v2 2/7] net: page_pool: shrink &page_pool_params a tiny bit Alexander Lobakin
2023-07-14 17:08 ` [PATCH RFC net-next v2 3/7] net: page_pool: place frag_* fields in one cacheline Alexander Lobakin
2023-07-14 17:08 ` [PATCH RFC net-next v2 3/7] net: page_pool: shrink &page_pool_params a tiny bit Alexander Lobakin
2023-07-14 17:08 ` [PATCH RFC net-next v2 4/7] net: page_pool: don't use driver-set flags field directly Alexander Lobakin
2023-07-14 17:08 ` [PATCH RFC net-next v2 5/7] net: page_pool: avoid calling no-op externals when possible Alexander Lobakin
2023-07-14 17:08 ` [PATCH RFC net-next v2 6/7] net: skbuff: avoid accessing page_pool if !napi_safe when returning page Alexander Lobakin
2023-07-14 17:08 ` [PATCH RFC net-next v2 7/7] net: skbuff: always try to recycle PP pages directly when in softirq Alexander Lobakin
2023-07-19 0:40 ` Jakub Kicinski
2023-07-19 16:34 ` Alexander Lobakin
2023-07-19 20:51 ` Jakub Kicinski [this message]
2023-07-20 16:46 ` Alexander Lobakin
2023-07-20 17:12 ` Jakub Kicinski
2023-07-20 17:48 ` Alexander Lobakin
2023-07-20 18:00 ` Jakub Kicinski
2023-07-20 18:01 ` Alexander Lobakin
2023-07-20 18:13 ` Alexander Lobakin
2023-07-20 19:20 ` Jakub Kicinski
2023-07-20 19:33 ` Alexander Lobakin
2023-07-20 19:46 ` Jakub Kicinski
2023-07-21 11:53 ` Yunsheng Lin
2023-07-21 15:37 ` Alexander Lobakin
2023-07-21 16:01 ` Jakub Kicinski
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