On 2021/9/23 16:33, Ilias Apalodimas wrote:
On Wed, Sep 22, 2021 at 05:41:27PM +0800, Yunsheng Lin wrote:
quoted
As the pp page for a skb frag is always a head page, so make
sure skb_pp_recycle() passes a head page to avoid calling
compound_head() for skb frag page case.
Doesn't that rely on the driver mostly (i.e what's passed in skb_frag_set_page() ?
None of the current netstack code assumes bv_page is the head page of a
compound page. Since our page_pool allocator can will allocate compound
pages for order > 0, why should we rely on it ?
As the page pool alloc function return 'struct page *' to the caller, which
is the head page of a compound pages for order > 0, so I assume the caller
will pass that to skb_frag_set_page().
For non-pp page, I assume it is ok whether the page is a head page or tail
page, as the pp_magic for both of them are not set with PP_SIGNATURE.
Or should we play safe here, and do the trick as skb_free_head() does in
patch 6?
Thanks
/Ilias
quoted
Signed-off-by: Yunsheng Lin <redacted>
---
include/linux/skbuff.h | 2 +-
net/core/page_pool.c | 2 --
2 files changed, 1 insertion(+), 3 deletions(-)
diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
index 6bdb0db3e825..35eebc2310a5 100644
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h
@@ -4722,7 +4722,7 @@ static inline bool skb_pp_recycle(struct sk_buff *skb, void *data)
{
if (!IS_ENABLED(CONFIG_PAGE_POOL) || !skb->pp_recycle)
return false;
- return page_pool_return_skb_page(virt_to_page(data));
+ return page_pool_return_skb_page(virt_to_head_page(data));
}
#endif /* __KERNEL__ */diff --git a/net/core/page_pool.c b/net/core/page_pool.c
index f7e71dcb6a2e..357fb53343a0 100644
--- a/net/core/page_pool.c
+++ b/net/core/page_pool.c
@@ -742,8 +742,6 @@ bool page_pool_return_skb_page(struct page *page)
{
struct page_pool *pp;
- page = compound_head(page);
-
/* page->pp_magic is OR'ed with PP_SIGNATURE after the allocation
* in order to preserve any existing bits, such as bit 0 for the
* head page of compound page and bit 1 for pfmemalloc page, so--
2.33.0
.