[PATCH net-next v1 0/7] devmem TCP fixes

[PATCH net-next v1 0/7] devmem TCP fixes

[Mina Almasry]

A few unrelated devmem TCP fixes bundled in a series for some
convenience (if that's ok).

Patch 1-2: fix naming and provide page_pool_alloc_netmem for fragged
netmem.

Patch 3-4: fix issues with dma-buf dma addresses being potentially
passed to dma_sync_for_* helpers.

Patch 5-6: fix syzbot SO_DEVMEM_DONTNEED issue and add test for this
case.


Mina Almasry (6):
  net: page_pool: rename page_pool_alloc_netmem to *_netmems
  net: page_pool: create page_pool_alloc_netmem
  page_pool: disable sync for cpu for dmabuf memory provider
  netmem: add netmem_prefetch
  net: fix SO_DEVMEM_DONTNEED looping too long
  ncdevmem: add test for too many token_count

Samiullah Khawaja (1):
  page_pool: Set `dma_sync` to false for devmem memory provider

 include/net/netmem.h                   |  7 ++++
 include/net/page_pool/helpers.h        | 50 ++++++++++++++++++--------
 include/net/page_pool/types.h          |  2 +-
 net/core/devmem.c                      |  9 +++--
 net/core/page_pool.c                   | 11 +++---
 net/core/sock.c                        | 46 ++++++++++++++----------
 tools/testing/selftests/net/ncdevmem.c | 11 ++++++
 7 files changed, 93 insertions(+), 43 deletions(-)

-- 
2.47.0.163.g1226f6d8fa-goog

[PATCH net-next v1 1/7] net: page_pool: rename page_pool_alloc_netmem to *_netmems

[Mina Almasry]

page_pool_alloc_netmem (without an s) was the mirror of
page_pool_alloc_pages (with an s), which was confusing.

Rename to page_pool_alloc_netmems so it's the mirror of
page_pool_alloc_pages.

Signed-off-by: Mina Almasry <almasrymina@google.com>
---
 include/net/page_pool/types.h | 2 +-
 net/core/page_pool.c          | 8 ++++----
 2 files changed, 5 insertions(+), 5 deletions(-)

diff --git a/include/net/page_pool/types.h b/include/net/page_pool/types.h
index c022c410abe3..8f564fe9eb9a 100644
--- a/include/net/page_pool/types.h
+++ b/include/net/page_pool/types.h
@@ -242,7 +242,7 @@ struct page_pool {
 };
 
 struct page *page_pool_alloc_pages(struct page_pool *pool, gfp_t gfp);
-netmem_ref page_pool_alloc_netmem(struct page_pool *pool, gfp_t gfp);
+netmem_ref page_pool_alloc_netmems(struct page_pool *pool, gfp_t gfp);
 struct page *page_pool_alloc_frag(struct page_pool *pool, unsigned int *offset,
 				  unsigned int size, gfp_t gfp);
 netmem_ref page_pool_alloc_frag_netmem(struct page_pool *pool,
diff --git a/net/core/page_pool.c b/net/core/page_pool.c
index a813d30d2135..77de79c1933b 100644
--- a/net/core/page_pool.c
+++ b/net/core/page_pool.c
@@ -574,7 +574,7 @@ static noinline netmem_ref __page_pool_alloc_pages_slow(struct page_pool *pool,
 /* For using page_pool replace: alloc_pages() API calls, but provide
  * synchronization guarantee for allocation side.
  */
-netmem_ref page_pool_alloc_netmem(struct page_pool *pool, gfp_t gfp)
+netmem_ref page_pool_alloc_netmems(struct page_pool *pool, gfp_t gfp)
 {
 	netmem_ref netmem;
 
@@ -590,11 +590,11 @@ netmem_ref page_pool_alloc_netmem(struct page_pool *pool, gfp_t gfp)
 		netmem = __page_pool_alloc_pages_slow(pool, gfp);
 	return netmem;
 }
-EXPORT_SYMBOL(page_pool_alloc_netmem);
+EXPORT_SYMBOL(page_pool_alloc_netmems);
 
 struct page *page_pool_alloc_pages(struct page_pool *pool, gfp_t gfp)
 {
-	return netmem_to_page(page_pool_alloc_netmem(pool, gfp));
+	return netmem_to_page(page_pool_alloc_netmems(pool, gfp));
 }
 EXPORT_SYMBOL(page_pool_alloc_pages);
 ALLOW_ERROR_INJECTION(page_pool_alloc_pages, NULL);
@@ -956,7 +956,7 @@ netmem_ref page_pool_alloc_frag_netmem(struct page_pool *pool,
 	}
 
 	if (!netmem) {
-		netmem = page_pool_alloc_netmem(pool, gfp);
+		netmem = page_pool_alloc_netmems(pool, gfp);
 		if (unlikely(!netmem)) {
 			pool->frag_page = 0;
 			return 0;
-- 
2.47.0.163.g1226f6d8fa-goog

[PATCH net-next v1 2/7] net: page_pool: create page_pool_alloc_netmem

[Mina Almasry]

Create page_pool_alloc_netmem to be the mirror of page_pool_alloc.

This enables drivers that want currently use page_pool_alloc to
transition to netmem by converting the call sites to
page_pool_alloc_netmem.

Signed-off-by: Mina Almasry <almasrymina@google.com>
---
 include/net/page_pool/helpers.h | 25 ++++++++++++++++---------
 1 file changed, 16 insertions(+), 9 deletions(-)

diff --git a/include/net/page_pool/helpers.h b/include/net/page_pool/helpers.h
index 793e6fd78bc5..8e548ff3044c 100644
--- a/include/net/page_pool/helpers.h
+++ b/include/net/page_pool/helpers.h
@@ -116,22 +116,22 @@ static inline struct page *page_pool_dev_alloc_frag(struct page_pool *pool,
 	return page_pool_alloc_frag(pool, offset, size, gfp);
 }
 
-static inline struct page *page_pool_alloc(struct page_pool *pool,
-					   unsigned int *offset,
-					   unsigned int *size, gfp_t gfp)
+static inline netmem_ref page_pool_alloc_netmem(struct page_pool *pool,
+						unsigned int *offset,
+						unsigned int *size, gfp_t gfp)
 {
 	unsigned int max_size = PAGE_SIZE << pool->p.order;
-	struct page *page;
+	netmem_ref netmem;
 
 	if ((*size << 1) > max_size) {
 		*size = max_size;
 		*offset = 0;
-		return page_pool_alloc_pages(pool, gfp);
+		return page_pool_alloc_netmems(pool, gfp);
 	}
 
-	page = page_pool_alloc_frag(pool, offset, *size, gfp);
-	if (unlikely(!page))
-		return NULL;
+	netmem = page_pool_alloc_frag_netmem(pool, offset, *size, gfp);
+	if (unlikely(!netmem))
+		return 0;
 
 	/* There is very likely not enough space for another fragment, so append
 	 * the remaining size to the current fragment to avoid truesize
@@ -142,7 +142,14 @@ static inline struct page *page_pool_alloc(struct page_pool *pool,
 		pool->frag_offset = max_size;
 	}
 
-	return page;
+	return netmem;
+}
+
+static inline struct page *page_pool_alloc(struct page_pool *pool,
+					   unsigned int *offset,
+					   unsigned int *size, gfp_t gfp)
+{
+	return netmem_to_page(page_pool_alloc_netmem(pool, offset, size, gfp));
 }
 
 /**
-- 
2.47.0.163.g1226f6d8fa-goog

Re: [PATCH net-next v1 2/7] net: page_pool: create page_pool_alloc_netmem

[Yunsheng Lin]

On 2024/10/30 4:45, Mina Almasry wrote:
> Create page_pool_alloc_netmem to be the mirror of page_pool_alloc.
> 
> This enables drivers that want currently use page_pool_alloc to
> transition to netmem by converting the call sites to
> page_pool_alloc_netmem.

For old API, page_pool_alloc_pages() always return a whole page, and
page_pool_alloc() returns a whole page or a page fragment based on the
requested size.

For new netmem API, page_pool_alloc_netmems() always return a whole
netmem, and page_pool_alloc_netmem() returns a whole netmem or a netmem
fragment based on the requested size.

Isn't it a little odd that old and new are not following the same
pattern?

Re: [PATCH net-next v1 2/7] net: page_pool: create page_pool_alloc_netmem

[Mina Almasry]

On Fri, Nov 1, 2024 at 4:14 AM Yunsheng Lin <linyunsheng@huawei.com> wrote:
>
> On 2024/10/30 4:45, Mina Almasry wrote:
> > Create page_pool_alloc_netmem to be the mirror of page_pool_alloc.
> >
> > This enables drivers that want currently use page_pool_alloc to
> > transition to netmem by converting the call sites to
> > page_pool_alloc_netmem.
>
> For old API, page_pool_alloc_pages() always return a whole page, and
> page_pool_alloc() returns a whole page or a page fragment based on the
> requested size.
>
> For new netmem API, page_pool_alloc_netmems() always return a whole
> netmem, and page_pool_alloc_netmem() returns a whole netmem or a netmem
> fragment based on the requested size.
>
> Isn't it a little odd that old and new are not following the same
> pattern?

Hi Yunsheng,

The intention is that page_pool_alloc_pages is mirrored by
page_pool_alloc_netmems.

And page_pool_alloc is mirrored by page_pool_alloc_netmem.

From your description, the behavior is the same for each function and
its mirror. What is the gap in the pattern that you see?

-- 
Thanks,
Mina

Re: [PATCH net-next v1 2/7] net: page_pool: create page_pool_alloc_netmem

[Yunsheng Lin]

On 11/1/2024 9:10 PM, Mina Almasry wrote:

...

>>
>> Isn't it a little odd that old and new are not following the same
>> pattern?
> 
> Hi Yunsheng,
> 
> The intention is that page_pool_alloc_pages is mirrored by
> page_pool_alloc_netmems.
> 
> And page_pool_alloc is mirrored by page_pool_alloc_netmem.
> 
>>From your description, the behavior is the same for each function and
> its mirror. What is the gap in the pattern that you see?

I was mostly referring to the API naming pattern.

Isn't it better if page_pool_alloc is mirrored by netmem_pool_alloc and
netmem_pool_alloc_netmems is mirrored by page_pool_alloc_pages() from
API naming prespective?

And maybe page_pool_alloc_frag can be mirrored by netmem_pool_alloc_frag
in the future?

Also, it would be good to update Documentation/networking/page_pool.rst
for those new netmem APIs, or create a new doc file for them.

> 

Re: [PATCH net-next v1 2/7] net: page_pool: create page_pool_alloc_netmem

[Mina Almasry]

On Sun, Nov 3, 2024 at 6:35 AM Yunsheng Lin <yunshenglin0825@gmail.com> wrote:
>
> On 11/1/2024 9:10 PM, Mina Almasry wrote:
>
> ...
>
> >>
> >> Isn't it a little odd that old and new are not following the same
> >> pattern?
> >
> > Hi Yunsheng,
> >
> > The intention is that page_pool_alloc_pages is mirrored by
> > page_pool_alloc_netmems.
> >
> > And page_pool_alloc is mirrored by page_pool_alloc_netmem.
> >
> >>From your description, the behavior is the same for each function and
> > its mirror. What is the gap in the pattern that you see?
>
> I was mostly referring to the API naming pattern.
>
> Isn't it better if page_pool_alloc is mirrored by netmem_pool_alloc and
> netmem_pool_alloc_netmems is mirrored by page_pool_alloc_pages() from
> API naming prespective?
>

I've been treating the page_pool_* prefix to all the page_pool
functions as constant in all the renames so far. I replace 'page' with
'netmem' when available, or add a _netmem postfix when available.

> And maybe page_pool_alloc_frag can be mirrored by netmem_pool_alloc_frag
> in the future?
>
> Also, it would be good to update Documentation/networking/page_pool.rst
> for those new netmem APIs, or create a new doc file for them.
>

Heard. I do have an action item to update the docs. Currently, outside
of drivers immediately looking to immediately adopt devmem tcp, there
is no need yet to use the netmem APIs, but I do hope to make them more
widespread (and perhaps deprecate the page APIs when it's time to do
so).

-- 
Thanks,
Mina

[PATCH net-next v1 3/7] page_pool: Set `dma_sync` to false for devmem memory provider

[Mina Almasry]

From: Samiullah Khawaja <skhawaja@google.com>

Move the `dma_map` and `dma_sync` checks to `page_pool_init` to make
them generic. Set dma_sync to false for devmem memory provider because
the dma_sync APIs should not be used for dma_buf backed devmem memory
provider.

Cc: Jason Gunthorpe <jgg@ziepe.ca>
Signed-off-by: Samiullah Khawaja <skhawaja@google.com>
Signed-off-by: Mina Almasry <almasrymina@google.com>

---
 net/core/devmem.c    | 9 ++++-----
 net/core/page_pool.c | 3 +++
 2 files changed, 7 insertions(+), 5 deletions(-)

diff --git a/net/core/devmem.c b/net/core/devmem.c
index 11b91c12ee11..826d0b00159f 100644
--- a/net/core/devmem.c
+++ b/net/core/devmem.c
@@ -331,11 +331,10 @@ int mp_dmabuf_devmem_init(struct page_pool *pool)
 	if (!binding)
 		return -EINVAL;
 
-	if (!pool->dma_map)
-		return -EOPNOTSUPP;
-
-	if (pool->dma_sync)
-		return -EOPNOTSUPP;
+	/* dma-buf dma addresses should not be used with
+	 * dma_sync_for_cpu/device. Force disable dma_sync.
+	 */
+	pool->dma_sync = false;
 
 	if (pool->p.order != 0)
 		return -E2BIG;
diff --git a/net/core/page_pool.c b/net/core/page_pool.c
index 77de79c1933b..528dd4d18eab 100644
--- a/net/core/page_pool.c
+++ b/net/core/page_pool.c
@@ -287,6 +287,9 @@ static int page_pool_init(struct page_pool *pool,
 	}
 
 	if (pool->mp_priv) {
+		if (!pool->dma_map || !pool->dma_sync)
+			return -EOPNOTSUPP;
+
 		err = mp_dmabuf_devmem_init(pool);
 		if (err) {
 			pr_warn("%s() mem-provider init failed %d\n", __func__,
-- 
2.47.0.163.g1226f6d8fa-goog

[PATCH net-next v1 4/7] page_pool: disable sync for cpu for dmabuf memory provider

[Mina Almasry]

dmabuf dma-addresses should not be dma_sync'd for CPU/device. Typically
its the driver responsibility to dma_sync for CPU, but the driver should
not dma_sync for CPU if the netmem is actually coming from a dmabuf
memory provider.

The page_pool already exposes a helper for dma_sync_for_cpu:
page_pool_dma_sync_for_cpu. Upgrade this existing helper to handle
netmem, and have it skip dma_sync if the memory is from a dmabuf memory
provider. Drivers should migrate to using this helper when adding
support for netmem.

Cc: Jason Gunthorpe <jgg@ziepe.ca>
Signed-off-by: Mina Almasry <almasrymina@google.com>

---
 include/net/page_pool/helpers.h | 25 +++++++++++++++++++------
 1 file changed, 19 insertions(+), 6 deletions(-)

diff --git a/include/net/page_pool/helpers.h b/include/net/page_pool/helpers.h
index 8e548ff3044c..ad4fed4a791c 100644
--- a/include/net/page_pool/helpers.h
+++ b/include/net/page_pool/helpers.h
@@ -429,9 +429,10 @@ static inline dma_addr_t page_pool_get_dma_addr(const struct page *page)
 }
 
 /**
- * page_pool_dma_sync_for_cpu - sync Rx page for CPU after it's written by HW
+ * page_pool_dma_sync_netmem_for_cpu - sync Rx page for CPU after it's written
+ *				       by HW
  * @pool: &page_pool the @page belongs to
- * @page: page to sync
+ * @netmem: netmem to sync
  * @offset: offset from page start to "hard" start if using PP frags
  * @dma_sync_size: size of the data written to the page
  *
@@ -440,16 +441,28 @@ static inline dma_addr_t page_pool_get_dma_addr(const struct page *page)
  * Note that this version performs DMA sync unconditionally, even if the
  * associated PP doesn't perform sync-for-device.
  */
-static inline void page_pool_dma_sync_for_cpu(const struct page_pool *pool,
-					      const struct page *page,
-					      u32 offset, u32 dma_sync_size)
+static inline void
+page_pool_dma_sync_netmem_for_cpu(const struct page_pool *pool,
+				  const netmem_ref netmem, u32 offset,
+				  u32 dma_sync_size)
 {
+	if (pool->mp_priv)
+		return;
+
 	dma_sync_single_range_for_cpu(pool->p.dev,
-				      page_pool_get_dma_addr(page),
+				      page_pool_get_dma_addr_netmem(netmem),
 				      offset + pool->p.offset, dma_sync_size,
 				      page_pool_get_dma_dir(pool));
 }
 
+static inline void page_pool_dma_sync_for_cpu(const struct page_pool *pool,
+					      struct page *page, u32 offset,
+					      u32 dma_sync_size)
+{
+	page_pool_dma_sync_netmem_for_cpu(pool, page_to_netmem(page), offset,
+					  dma_sync_size);
+}
+
 static inline bool page_pool_put(struct page_pool *pool)
 {
 	return refcount_dec_and_test(&pool->user_cnt);
-- 
2.47.0.163.g1226f6d8fa-goog

[PATCH net-next v1 5/7] netmem: add netmem_prefetch

[Mina Almasry]

prefect(page) is a common thing to be called from drivers. Add
netmem_prefetch that can be called on generic netmem. Skips the prefetch
for net_iovs.

Signed-off-by: Mina Almasry <almasrymina@google.com>
---
 include/net/netmem.h | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/include/net/netmem.h b/include/net/netmem.h
index 8a6e20be4b9d..923c47147aa8 100644
--- a/include/net/netmem.h
+++ b/include/net/netmem.h
@@ -171,4 +171,11 @@ static inline unsigned long netmem_get_dma_addr(netmem_ref netmem)
 	return __netmem_clear_lsb(netmem)->dma_addr;
 }
 
+static inline void netmem_prefetch(netmem_ref netmem)
+{
+	if (netmem_is_net_iov(netmem))
+		return;
+
+	prefetch(netmem_to_page(netmem));
+}
 #endif /* _NET_NETMEM_H */
-- 
2.47.0.163.g1226f6d8fa-goog