From: Mina Almasry <almasrymina@google.com>
To: David Ahern <dsahern@kernel.org>
Cc: netdev@vger.kernel.org, linux-kernel@vger.kernel.org,
linux-arch@vger.kernel.org, linux-kselftest@vger.kernel.org,
linux-media@vger.kernel.org, dri-devel@lists.freedesktop.org,
linaro-mm-sig@lists.linaro.org,
"David S. Miller" <davem@davemloft.net>,
"Eric Dumazet" <edumazet@google.com>,
"Jakub Kicinski" <kuba@kernel.org>,
"Paolo Abeni" <pabeni@redhat.com>,
"Jesper Dangaard Brouer" <hawk@kernel.org>,
"Ilias Apalodimas" <ilias.apalodimas@linaro.org>,
"Arnd Bergmann" <arnd@arndb.de>,
"Willem de Bruijn" <willemdebruijn.kernel@gmail.com>,
"Shuah Khan" <shuah@kernel.org>,
"Sumit Semwal" <sumit.semwal@linaro.org>,
"Christian König" <christian.koenig@amd.com>,
"Shakeel Butt" <shakeelb@google.com>,
"Jeroen de Borst" <jeroendb@google.com>,
"Praveen Kaligineedi" <pkaligineedi@google.com>,
"Willem de Bruijn" <willemb@google.com>,
"Kaiyuan Zhang" <kaiyuanz@google.com>
Subject: Re: [RFC PATCH v3 05/12] netdev: netdevice devmem allocator
Date: Tue, 7 Nov 2023 14:10:52 -0800 [thread overview]
Message-ID: <CAHS8izOHYx+oYnzksUDrK1S0+6CdMJmirApntP5W862yFumezw@mail.gmail.com> (raw)
In-Reply-To: <3b0d612c-e33b-48aa-a861-fbb042572fc9@kernel.org>
On Mon, Nov 6, 2023 at 3:44 PM David Ahern <dsahern@kernel.org> wrote:
>
> On 11/5/23 7:44 PM, Mina Almasry wrote:
> > diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
> > index eeeda849115c..1c351c138a5b 100644
> > --- a/include/linux/netdevice.h
> > +++ b/include/linux/netdevice.h
> > @@ -843,6 +843,9 @@ struct netdev_dmabuf_binding {
> > };
> >
> > #ifdef CONFIG_DMA_SHARED_BUFFER
> > +struct page_pool_iov *
> > +netdev_alloc_devmem(struct netdev_dmabuf_binding *binding);
> > +void netdev_free_devmem(struct page_pool_iov *ppiov);
>
> netdev_{alloc,free}_dmabuf?
>
Can do.
> I say that because a dmabuf can be host memory, at least I am not aware
> of a restriction that a dmabuf is device memory.
>
In my limited experience dma-buf is generally device memory, and
that's really its use case. CONFIG_UDMABUF is a driver that mocks
dma-buf with a memfd which I think is used for testing. But I can do
the rename, it's more clear anyway, I think.
On Mon, Nov 6, 2023 at 11:45 PM Yunsheng Lin <linyunsheng@huawei.com> wrote:
>
> On 2023/11/6 10:44, Mina Almasry wrote:
> > +
> > +void netdev_free_devmem(struct page_pool_iov *ppiov)
> > +{
> > + struct netdev_dmabuf_binding *binding = page_pool_iov_binding(ppiov);
> > +
> > + refcount_set(&ppiov->refcount, 1);
> > +
> > + if (gen_pool_has_addr(binding->chunk_pool,
> > + page_pool_iov_dma_addr(ppiov), PAGE_SIZE))
>
> When gen_pool_has_addr() returns false, does it mean something has gone
> really wrong here?
>
Yes, good eye. gen_pool_has_addr() should never return false, but then
again, gen_pool_free() BUG_ON()s if it doesn't find the address,
which is an extremely severe reaction to what can be a minor bug in
the accounting. I prefer to leak rather than crash the machine. It's a
bit of defensive programming that is normally frowned upon, but I feel
like in this case it's maybe warranted due to the very severe reaction
(BUG_ON).
--
Thanks,
Mina
WARNING: multiple messages have this Message-ID (diff)
From: Mina Almasry <almasrymina@google.com>
To: David Ahern <dsahern@kernel.org>
Cc: "Kaiyuan Zhang" <kaiyuanz@google.com>,
dri-devel@lists.freedesktop.org,
"Eric Dumazet" <edumazet@google.com>,
linux-kselftest@vger.kernel.org, "Shuah Khan" <shuah@kernel.org>,
"Sumit Semwal" <sumit.semwal@linaro.org>,
linux-arch@vger.kernel.org,
"Willem de Bruijn" <willemdebruijn.kernel@gmail.com>,
"Jeroen de Borst" <jeroendb@google.com>,
"Jakub Kicinski" <kuba@kernel.org>,
"Paolo Abeni" <pabeni@redhat.com>,
linux-media@vger.kernel.org,
"Jesper Dangaard Brouer" <hawk@kernel.org>,
"Arnd Bergmann" <arnd@arndb.de>,
linaro-mm-sig@lists.linaro.org,
"Shakeel Butt" <shakeelb@google.com>,
"Willem de Bruijn" <willemb@google.com>,
netdev@vger.kernel.org,
"Ilias Apalodimas" <ilias.apalodimas@linaro.org>,
linux-kernel@vger.kernel.org,
"David S. Miller" <davem@davemloft.net>,
"Praveen Kaligineedi" <pkaligineedi@google.com>,
"Christian König" <christian.koenig@amd.com>
Subject: Re: [RFC PATCH v3 05/12] netdev: netdevice devmem allocator
Date: Tue, 7 Nov 2023 14:10:52 -0800 [thread overview]
Message-ID: <CAHS8izOHYx+oYnzksUDrK1S0+6CdMJmirApntP5W862yFumezw@mail.gmail.com> (raw)
In-Reply-To: <3b0d612c-e33b-48aa-a861-fbb042572fc9@kernel.org>
On Mon, Nov 6, 2023 at 3:44 PM David Ahern <dsahern@kernel.org> wrote:
>
> On 11/5/23 7:44 PM, Mina Almasry wrote:
> > diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
> > index eeeda849115c..1c351c138a5b 100644
> > --- a/include/linux/netdevice.h
> > +++ b/include/linux/netdevice.h
> > @@ -843,6 +843,9 @@ struct netdev_dmabuf_binding {
> > };
> >
> > #ifdef CONFIG_DMA_SHARED_BUFFER
> > +struct page_pool_iov *
> > +netdev_alloc_devmem(struct netdev_dmabuf_binding *binding);
> > +void netdev_free_devmem(struct page_pool_iov *ppiov);
>
> netdev_{alloc,free}_dmabuf?
>
Can do.
> I say that because a dmabuf can be host memory, at least I am not aware
> of a restriction that a dmabuf is device memory.
>
In my limited experience dma-buf is generally device memory, and
that's really its use case. CONFIG_UDMABUF is a driver that mocks
dma-buf with a memfd which I think is used for testing. But I can do
the rename, it's more clear anyway, I think.
On Mon, Nov 6, 2023 at 11:45 PM Yunsheng Lin <linyunsheng@huawei.com> wrote:
>
> On 2023/11/6 10:44, Mina Almasry wrote:
> > +
> > +void netdev_free_devmem(struct page_pool_iov *ppiov)
> > +{
> > + struct netdev_dmabuf_binding *binding = page_pool_iov_binding(ppiov);
> > +
> > + refcount_set(&ppiov->refcount, 1);
> > +
> > + if (gen_pool_has_addr(binding->chunk_pool,
> > + page_pool_iov_dma_addr(ppiov), PAGE_SIZE))
>
> When gen_pool_has_addr() returns false, does it mean something has gone
> really wrong here?
>
Yes, good eye. gen_pool_has_addr() should never return false, but then
again, gen_pool_free() BUG_ON()s if it doesn't find the address,
which is an extremely severe reaction to what can be a minor bug in
the accounting. I prefer to leak rather than crash the machine. It's a
bit of defensive programming that is normally frowned upon, but I feel
like in this case it's maybe warranted due to the very severe reaction
(BUG_ON).
--
Thanks,
Mina
next prev parent reply other threads:[~2023-11-07 22:11 UTC|newest]
Thread overview: 254+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-11-06 2:43 [RFC PATCH v3 00/12] Device Memory TCP Mina Almasry
2023-11-06 2:43 ` Mina Almasry
2023-11-06 2:44 ` [RFC PATCH v3 01/12] net: page_pool: factor out releasing DMA from releasing the page Mina Almasry
2023-11-06 2:44 ` Mina Almasry
2023-11-06 2:44 ` [RFC PATCH v3 02/12] net: page_pool: create hooks for custom page providers Mina Almasry
2023-11-06 2:44 ` Mina Almasry
2023-11-07 7:44 ` Yunsheng Lin
2023-11-07 7:44 ` Yunsheng Lin
2023-11-09 11:09 ` Paolo Abeni
2023-11-09 11:09 ` Paolo Abeni
2023-11-10 23:19 ` Jakub Kicinski
2023-11-10 23:19 ` Jakub Kicinski
2023-11-13 3:28 ` Mina Almasry
2023-11-13 3:28 ` Mina Almasry
2023-11-13 22:10 ` Jakub Kicinski
2023-11-13 22:10 ` Jakub Kicinski
2023-11-06 2:44 ` [RFC PATCH v3 03/12] net: netdev netlink api to bind dma-buf to a net device Mina Almasry
2023-11-06 2:44 ` Mina Almasry
2023-11-10 23:16 ` Jakub Kicinski
2023-11-10 23:16 ` Jakub Kicinski
2023-11-06 2:44 ` [RFC PATCH v3 04/12] netdev: support binding dma-buf to netdevice Mina Almasry
2023-11-06 2:44 ` Mina Almasry
2023-11-07 7:46 ` Yunsheng Lin
2023-11-07 7:46 ` Yunsheng Lin
2023-11-07 21:59 ` Mina Almasry
2023-11-07 21:59 ` Mina Almasry
2023-11-08 3:40 ` Yunsheng Lin
2023-11-08 3:40 ` Yunsheng Lin
2023-11-09 2:22 ` Mina Almasry
2023-11-09 2:22 ` Mina Almasry
2023-11-09 9:29 ` Yunsheng Lin
2023-11-09 9:29 ` Yunsheng Lin
2023-11-08 23:47 ` David Wei
2023-11-08 23:47 ` David Wei
2023-11-09 2:25 ` Mina Almasry
2023-11-09 2:25 ` Mina Almasry
2023-11-09 8:29 ` Paolo Abeni
2023-11-09 8:29 ` Paolo Abeni
2023-11-10 2:59 ` Mina Almasry
2023-11-10 2:59 ` Mina Almasry
2023-11-10 7:38 ` Yunsheng Lin
2023-11-10 7:38 ` Yunsheng Lin
2023-11-10 9:45 ` Mina Almasry
2023-11-10 9:45 ` Mina Almasry
2023-11-10 23:19 ` Jakub Kicinski
2023-11-10 23:19 ` Jakub Kicinski
2023-11-11 2:19 ` Mina Almasry
2023-11-11 2:19 ` Mina Almasry
2023-11-06 2:44 ` [RFC PATCH v3 05/12] netdev: netdevice devmem allocator Mina Almasry
2023-11-06 2:44 ` Mina Almasry
2023-11-06 23:44 ` David Ahern
2023-11-06 23:44 ` David Ahern
2023-11-07 22:10 ` Mina Almasry [this message]
2023-11-07 22:10 ` Mina Almasry
2023-11-07 22:55 ` David Ahern
2023-11-07 22:55 ` David Ahern
2023-11-07 23:03 ` Mina Almasry
2023-11-07 23:03 ` Mina Almasry
2023-11-09 1:15 ` David Wei
2023-11-09 1:15 ` David Wei
2023-11-10 14:26 ` Pavel Begunkov
2023-11-10 14:26 ` Pavel Begunkov
2023-11-11 17:19 ` David Ahern
2023-11-11 17:19 ` David Ahern
2023-11-14 16:09 ` Pavel Begunkov
2023-11-14 16:09 ` Pavel Begunkov
2023-11-09 1:00 ` David Wei
2023-11-09 1:00 ` David Wei
2023-11-08 3:48 ` Yunsheng Lin
2023-11-08 3:48 ` Yunsheng Lin
2023-11-09 1:41 ` Mina Almasry
2023-11-09 1:41 ` Mina Almasry
2023-11-07 7:45 ` Yunsheng Lin
2023-11-07 7:45 ` Yunsheng Lin
2023-11-09 8:44 ` Paolo Abeni
2023-11-09 8:44 ` Paolo Abeni
2023-11-06 2:44 ` [RFC PATCH v3 06/12] memory-provider: dmabuf devmem memory provider Mina Almasry
2023-11-06 2:44 ` Mina Almasry
2023-11-06 21:02 ` Stanislav Fomichev
2023-11-06 21:02 ` Stanislav Fomichev
2023-11-06 23:49 ` David Ahern
2023-11-06 23:49 ` David Ahern
2023-11-08 0:02 ` Mina Almasry
2023-11-08 0:02 ` Mina Almasry
2023-11-08 0:10 ` David Ahern
2023-11-08 0:10 ` David Ahern
2023-11-10 23:16 ` Jakub Kicinski
2023-11-10 23:16 ` Jakub Kicinski
2023-11-13 4:54 ` Mina Almasry
2023-11-13 4:54 ` Mina Almasry
2023-11-06 2:44 ` [RFC PATCH v3 07/12] page-pool: device memory support Mina Almasry
2023-11-06 2:44 ` Mina Almasry
2023-11-07 8:00 ` Yunsheng Lin
2023-11-07 8:00 ` Yunsheng Lin
2023-11-07 21:56 ` Mina Almasry
2023-11-07 21:56 ` Mina Almasry
2023-11-08 10:56 ` Yunsheng Lin
2023-11-08 10:56 ` Yunsheng Lin
2023-11-09 3:20 ` Mina Almasry
2023-11-09 3:20 ` Mina Almasry
2023-11-09 9:30 ` Yunsheng Lin
2023-11-09 9:30 ` Yunsheng Lin
2023-11-09 12:20 ` Mina Almasry
2023-11-09 12:20 ` Mina Almasry
2023-11-09 13:23 ` Yunsheng Lin
2023-11-09 13:23 ` Yunsheng Lin
2023-11-09 14:23 ` Christian König
2023-11-09 9:01 ` Paolo Abeni
2023-11-09 9:01 ` Paolo Abeni
2023-11-06 2:44 ` [RFC PATCH v3 08/12] net: support non paged skb frags Mina Almasry
2023-11-06 2:44 ` Mina Almasry
2023-11-07 9:00 ` Yunsheng Lin
2023-11-07 9:00 ` Yunsheng Lin
2023-11-07 21:19 ` Mina Almasry
2023-11-07 21:19 ` Mina Almasry
2023-11-08 11:25 ` Yunsheng Lin
2023-11-08 11:25 ` Yunsheng Lin
2023-11-09 9:14 ` Paolo Abeni
2023-11-09 9:14 ` Paolo Abeni
2023-11-10 4:06 ` Mina Almasry
2023-11-10 4:06 ` Mina Almasry
2023-11-10 23:19 ` Jakub Kicinski
2023-11-10 23:19 ` Jakub Kicinski
2023-11-13 6:05 ` Mina Almasry
2023-11-13 6:05 ` Mina Almasry
2023-11-13 22:17 ` Jakub Kicinski
2023-11-13 22:17 ` Jakub Kicinski
2023-11-06 2:44 ` [RFC PATCH v3 09/12] net: add support for skbs with unreadable frags Mina Almasry
2023-11-06 2:44 ` Mina Almasry
2023-11-06 18:47 ` Stanislav Fomichev
2023-11-06 18:47 ` Stanislav Fomichev
2023-11-06 19:34 ` David Ahern
2023-11-06 19:34 ` David Ahern
2023-11-06 20:31 ` Mina Almasry
2023-11-06 20:31 ` Mina Almasry
2023-11-06 21:59 ` Stanislav Fomichev
2023-11-06 21:59 ` Stanislav Fomichev
2023-11-06 22:18 ` Mina Almasry
2023-11-06 22:18 ` Mina Almasry
2023-11-06 22:59 ` Stanislav Fomichev
2023-11-06 22:59 ` Stanislav Fomichev
2023-11-06 23:14 ` Kaiyuan Zhang
2023-11-06 23:27 ` Mina Almasry
2023-11-06 23:27 ` Mina Almasry
2023-11-06 23:55 ` Stanislav Fomichev
2023-11-06 23:55 ` Stanislav Fomichev
2023-11-07 0:07 ` Willem de Bruijn
2023-11-07 0:07 ` Willem de Bruijn
2023-11-07 0:14 ` Stanislav Fomichev
2023-11-07 0:14 ` Stanislav Fomichev
2023-11-07 0:59 ` Stanislav Fomichev
2023-11-07 0:59 ` Stanislav Fomichev
2023-11-07 2:23 ` Willem de Bruijn
2023-11-07 2:23 ` Willem de Bruijn
2023-11-07 17:44 ` Stanislav Fomichev
2023-11-07 17:44 ` Stanislav Fomichev
2023-11-07 17:57 ` Willem de Bruijn
2023-11-07 17:57 ` Willem de Bruijn
2023-11-07 18:14 ` Stanislav Fomichev
2023-11-07 18:14 ` Stanislav Fomichev
2023-11-07 0:20 ` Mina Almasry
2023-11-07 0:20 ` Mina Almasry
2023-11-07 1:06 ` Stanislav Fomichev
2023-11-07 1:06 ` Stanislav Fomichev
2023-11-07 19:53 ` Mina Almasry
2023-11-07 19:53 ` Mina Almasry
2023-11-07 21:05 ` Stanislav Fomichev
2023-11-07 21:05 ` Stanislav Fomichev
2023-11-07 21:17 ` Eric Dumazet
2023-11-07 21:17 ` Eric Dumazet
2023-11-07 22:23 ` Stanislav Fomichev
2023-11-07 22:23 ` Stanislav Fomichev
2023-11-10 23:17 ` Jakub Kicinski
2023-11-10 23:17 ` Jakub Kicinski
2023-11-10 23:19 ` Jakub Kicinski
2023-11-10 23:19 ` Jakub Kicinski
2023-11-07 1:09 ` David Ahern
2023-11-07 1:09 ` David Ahern
2023-11-06 23:37 ` David Ahern
2023-11-06 23:37 ` David Ahern
2023-11-07 0:03 ` Mina Almasry
2023-11-07 0:03 ` Mina Almasry
2023-11-06 20:56 ` Stanislav Fomichev
2023-11-06 20:56 ` Stanislav Fomichev
2023-11-07 0:16 ` David Ahern
2023-11-07 0:16 ` David Ahern
2023-11-07 0:23 ` Mina Almasry
2023-11-07 0:23 ` Mina Almasry
2023-11-08 14:43 ` David Laight
2023-11-08 14:43 ` David Laight
2023-11-06 2:44 ` [RFC PATCH v3 10/12] tcp: RX path for devmem TCP Mina Almasry
2023-11-06 2:44 ` Mina Almasry
2023-11-06 18:44 ` Stanislav Fomichev
2023-11-06 18:44 ` Stanislav Fomichev
2023-11-06 19:29 ` Mina Almasry
2023-11-06 19:29 ` Mina Almasry
2023-11-06 21:14 ` Willem de Bruijn
2023-11-06 21:14 ` Willem de Bruijn
2023-11-06 22:34 ` Stanislav Fomichev
2023-11-06 22:34 ` Stanislav Fomichev
2023-11-06 22:55 ` Willem de Bruijn
2023-11-06 22:55 ` Willem de Bruijn
2023-11-06 23:32 ` Stanislav Fomichev
2023-11-06 23:32 ` Stanislav Fomichev
2023-11-06 23:55 ` David Ahern
2023-11-06 23:55 ` David Ahern
2023-11-07 0:02 ` Willem de Bruijn
2023-11-07 0:02 ` Willem de Bruijn
2023-11-07 23:55 ` Mina Almasry
2023-11-07 23:55 ` Mina Almasry
2023-11-08 0:01 ` David Ahern
2023-11-08 0:01 ` David Ahern
2023-11-09 2:39 ` Mina Almasry
2023-11-09 2:39 ` Mina Almasry
2023-11-09 16:07 ` Edward Cree
2023-11-09 16:07 ` Edward Cree
2023-12-08 20:12 ` Pavel Begunkov
2023-12-08 20:12 ` Pavel Begunkov
2023-11-09 11:05 ` Paolo Abeni
2023-11-09 11:05 ` Paolo Abeni
2023-11-10 23:16 ` Jakub Kicinski
2023-11-10 23:16 ` Jakub Kicinski
2023-12-08 20:28 ` Pavel Begunkov
2023-12-08 20:28 ` Pavel Begunkov
2023-12-08 20:09 ` Pavel Begunkov
2023-12-08 20:09 ` Pavel Begunkov
2023-11-06 21:17 ` Stanislav Fomichev
2023-11-06 21:17 ` Stanislav Fomichev
2023-11-08 15:36 ` Edward Cree
2023-11-08 15:36 ` Edward Cree
2023-11-09 10:52 ` Paolo Abeni
2023-11-09 10:52 ` Paolo Abeni
2023-11-10 23:19 ` Jakub Kicinski
2023-11-10 23:19 ` Jakub Kicinski
2023-11-06 2:44 ` [RFC PATCH v3 11/12] net: add SO_DEVMEM_DONTNEED setsockopt to release RX pages Mina Almasry
2023-11-06 2:44 ` Mina Almasry
2023-11-06 2:44 ` [RFC PATCH v3 12/12] selftests: add ncdevmem, netcat for devmem TCP Mina Almasry
2023-11-06 2:44 ` Mina Almasry
2023-11-09 11:03 ` Paolo Abeni
2023-11-09 11:03 ` Paolo Abeni
2023-11-10 23:13 ` Jakub Kicinski
2023-11-10 23:13 ` Jakub Kicinski
2023-11-11 2:27 ` Mina Almasry
2023-11-11 2:27 ` Mina Almasry
2023-11-11 2:35 ` Jakub Kicinski
2023-11-11 2:35 ` Jakub Kicinski
2023-11-13 4:08 ` Mina Almasry
2023-11-13 4:08 ` Mina Almasry
2023-11-13 22:20 ` Jakub Kicinski
2023-11-13 22:20 ` Jakub Kicinski
2023-11-10 23:17 ` Jakub Kicinski
2023-11-10 23:17 ` Jakub Kicinski
2023-11-07 15:18 ` [RFC PATCH v3 00/12] Device Memory TCP David Ahern
2023-11-07 15:18 ` David Ahern
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