Abstract the memory type from the page_pool so we can later add support
for new memory types. Convert the page_pool to use the new netmem type
abstraction, rather than use struct page directly.
As of this patch the netmem type is a no-op abstraction: it's always a
struct page underneath. All the page pool internals are converted to
use struct netmem instead of struct page, and the page pool now exports
2 APIs:
1. The existing struct page API.
2. The new struct netmem API.
Keeping the existing API is transitional; we do not want to refactor all
the current drivers using the page pool at once.
The netmem abstraction is currently a no-op. The page_pool uses
page_to_netmem() to convert allocated pages to netmem, and uses
netmem_to_page() to convert the netmem back to pages to pass to mm APIs,
Follow up patches to this series add non-paged netmem support to the
page_pool. This change is factored out on its own to limit the code
churn to this 1 patch, for ease of code review.
Signed-off-by: Mina Almasry <almasrymina@google.com>
Reviewed-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://patch.msgid.link/20240628003253.1694510-6-almasrymina@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Add the netmem_ref type, an abstraction for network memory.
To add support for new memory types to the net stack, we must first
abstract the current memory type. Currently parts of the net stack
use struct page directly:
- page_pool
- drivers
- skb_frag_t
Originally the plan was to reuse struct page* for the new memory types,
and to set the LSB on the page* to indicate it's not really a page.
However, for compiler type checking we need to introduce a new type.
netmem_ref is introduced to abstract the underlying memory type.
Currently it's a no-op abstraction that is always a struct page
underneath. In parallel there is an undergoing effort to add support
for devmem to the net stack:
https://lore.kernel.org/netdev/20231208005250.2910004-1-almasrymina@google.com/
netmem_ref can be pointers to different underlying memory types, and the
low bits are set to indicate the memory type. Helpers are provided
to convert netmem pointers to the underlying memory type (currently only
struct page). In the devmem series helpers are provided so that calling
code can use netmem without worrying about the underlying memory type
unless absolutely necessary.
Reviewed-by: Shakeel Butt <shakeelb@google.com>
Signed-off-by: Mina Almasry <almasrymina@google.com>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
