Re: [PATCH net-next 3/7] pool_pool: avoid calling compound_head() for skb frag page

From
Ilias Apalodimas <ilias.apalodimas@linaro.org>
Date
2021-09-23 08:34:02
Also in
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Reply to
Yunsheng Lin, 2021-09-22
On Wed, Sep 22, 2021 at 05:41:27PM +0800, Yunsheng Lin wrote:
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 ?

Thanks
/Ilias
quoted hunk ↗ jump to hunk
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
Thread (26 messages) 26 messages, 3 authors, 2021-09-30
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