[net-next PATCH 1/6] net: Add skb_free_frag to replace use of put_page in freeing skb->head
From: Alexander Duyck <hidden>
Date: 2015-05-04 23:09:48
Also in:
linux-mm
Subsystem:
memory management, memory management - core, memory management - page allocator, networking [general], the rest · Maintainers:
Andrew Morton, David Hildenbrand, Vlastimil Babka, "David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, Linus Torvalds
This change adds a function called skb_free_frag which is meant to compliment the function __alloc_page_frag. The general idea is to enable a more lightweight version of page freeing since we don't actually need all the overhead of a put_page, and we don't quite fit the model of __free_pages. The model for this is based off of __free_pages since we don't actually need to deal with all of the cases that put_page handles. I incorporated the virt_to_head_page call and compound_order into the function as it actually allows for a signficant size reduction by reducing code duplication. In order to enable the function it was necessary to move __free_pages_ok from being a statically defined function so that I could use it in skbuff.c. Signed-off-by: Alexander Duyck <redacted> --- include/linux/gfp.h | 1 + include/linux/skbuff.h | 1 + mm/page_alloc.c | 4 +--- net/core/skbuff.c | 29 ++++++++++++++++++++++++++--- 4 files changed, 29 insertions(+), 6 deletions(-)
diff --git a/include/linux/gfp.h b/include/linux/gfp.h
index 97a9373e61e8..edd19a06e2ac 100644
--- a/include/linux/gfp.h
+++ b/include/linux/gfp.h@@ -365,6 +365,7 @@ extern void __free_pages(struct page *page, unsigned int order); extern void free_pages(unsigned long addr, unsigned int order); extern void free_hot_cold_page(struct page *page, bool cold); extern void free_hot_cold_page_list(struct list_head *list, bool cold); +extern void __free_pages_ok(struct page *page, unsigned int order); extern void __free_kmem_pages(struct page *page, unsigned int order); extern void free_kmem_pages(unsigned long addr, unsigned int order);
diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
index 9c2f793573fa..3bfe3340929e 100644
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h@@ -2186,6 +2186,7 @@ static inline struct sk_buff *netdev_alloc_skb_ip_align(struct net_device *dev, return __netdev_alloc_skb_ip_align(dev, length, GFP_ATOMIC); } +void skb_free_frag(void *head); void *napi_alloc_frag(unsigned int fragsz); struct sk_buff *__napi_alloc_skb(struct napi_struct *napi, unsigned int length, gfp_t gfp_mask);
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index ebffa0e4a9c0..ab9ba9360730 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c@@ -165,8 +165,6 @@ bool pm_suspended_storage(void) int pageblock_order __read_mostly; #endif -static void __free_pages_ok(struct page *page, unsigned int order); - /* * results with 256, 32 in the lowmem_reserve sysctl: * 1G machine -> (16M dma, 800M-16M normal, 1G-800M high)
@@ -815,7 +813,7 @@ static bool free_pages_prepare(struct page *page, unsigned int order) return true; } -static void __free_pages_ok(struct page *page, unsigned int order) +void __free_pages_ok(struct page *page, unsigned int order) { unsigned long flags; int migratetype;
diff --git a/net/core/skbuff.c b/net/core/skbuff.c
index 1e4278a4dd7e..754842557fb0 100644
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c@@ -428,6 +428,27 @@ refill: return page_address(page) + offset; } +/** + * skb_free_frag - free a page fragment + * @head: virtual address of page fragment + * + * Frees a page fragment allocated out of either a compound or order 0 page. + * The function itself is a hybrid between free_pages and free_compound_page + * which can be found in mm/page_alloc.c + */ +void skb_free_frag(void *head) +{ + struct page *page = virt_to_head_page(head); + + if (unlikely(put_page_testzero(page))) { + if (likely(PageHead(page))) + __free_pages_ok(page, compound_order(page)); + else + free_hot_cold_page(page, false); + } +} +EXPORT_SYMBOL(skb_free_frag); + static void *__netdev_alloc_frag(unsigned int fragsz, gfp_t gfp_mask) { unsigned long flags;
@@ -499,7 +520,7 @@ static struct sk_buff *__alloc_rx_skb(unsigned int length, gfp_t gfp_mask, if (likely(data)) { skb = build_skb(data, fragsz); if (unlikely(!skb)) - put_page(virt_to_head_page(data)); + skb_free_frag(data); } } else { skb = __alloc_skb(length, gfp_mask,
@@ -611,10 +632,12 @@ static void skb_clone_fraglist(struct sk_buff *skb) static void skb_free_head(struct sk_buff *skb) { + unsigned char *head = skb->head; + if (skb->head_frag) - put_page(virt_to_head_page(skb->head)); + skb_free_frag(head); else - kfree(skb->head); + kfree(head); } static void skb_release_data(struct sk_buff *skb)