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Subject[RFC net-next v3 07/29] net: don't track pfmemalloc for managed frags
Date
Managed pages contain pinned userspace pages and controlled by upper
layers, there is no need in tracking skb->pfmemalloc for them.

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
---
include/linux/skbuff.h | 28 +++++++++++++++++-----------
net/core/datagram.c | 7 +++++--
2 files changed, 22 insertions(+), 13 deletions(-)

diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
index 5407cfd9cb89..6cca146be1f4 100644
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h
@@ -2549,6 +2549,22 @@ static inline unsigned int skb_pagelen(const struct sk_buff *skb)
return skb_headlen(skb) + __skb_pagelen(skb);
}

+static inline void __skb_fill_page_desc_noacc(struct skb_shared_info *shinfo,
+ int i, struct page *page,
+ int off, int size)
+{
+ skb_frag_t *frag = &shinfo->frags[i];
+
+ /*
+ * Propagate page pfmemalloc to the skb if we can. The problem is
+ * that not all callers have unique ownership of the page but rely
+ * on page_is_pfmemalloc doing the right thing(tm).
+ */
+ frag->bv_page = page;
+ frag->bv_offset = off;
+ skb_frag_size_set(frag, size);
+}
+
/**
* __skb_fill_page_desc - initialise a paged fragment in an skb
* @skb: buffer containing fragment to be initialised
@@ -2565,17 +2581,7 @@ static inline unsigned int skb_pagelen(const struct sk_buff *skb)
static inline void __skb_fill_page_desc(struct sk_buff *skb, int i,
struct page *page, int off, int size)
{
- skb_frag_t *frag = &skb_shinfo(skb)->frags[i];
-
- /*
- * Propagate page pfmemalloc to the skb if we can. The problem is
- * that not all callers have unique ownership of the page but rely
- * on page_is_pfmemalloc doing the right thing(tm).
- */
- frag->bv_page = page;
- frag->bv_offset = off;
- skb_frag_size_set(frag, size);
-
+ __skb_fill_page_desc_noacc(skb_shinfo(skb), i, page, off, size);
page = compound_head(page);
if (page_is_pfmemalloc(page))
skb->pfmemalloc = true;
diff --git a/net/core/datagram.c b/net/core/datagram.c
index a93c05156f56..3c913a6342ad 100644
--- a/net/core/datagram.c
+++ b/net/core/datagram.c
@@ -616,7 +616,8 @@ EXPORT_SYMBOL(skb_copy_datagram_from_iter);
static int __zerocopy_sg_from_bvec(struct sock *sk, struct sk_buff *skb,
struct iov_iter *from, size_t length)
{
- int frag = skb_shinfo(skb)->nr_frags;
+ struct skb_shared_info *shinfo = skb_shinfo(skb);
+ int frag = shinfo->nr_frags;
int ret = 0;
struct bvec_iter bi;
ssize_t copied = 0;
@@ -631,12 +632,14 @@ static int __zerocopy_sg_from_bvec(struct sock *sk, struct sk_buff *skb,

copied += v.bv_len;
truesize += PAGE_ALIGN(v.bv_len + v.bv_offset);
- skb_fill_page_desc(skb, frag++, v.bv_page, v.bv_offset, v.bv_len);
+ __skb_fill_page_desc_noacc(shinfo, frag++, v.bv_page,
+ v.bv_offset, v.bv_len);
bvec_iter_advance_single(from->bvec, &bi, v.bv_len);
}
if (bi.bi_size)
ret = -EMSGSIZE;

+ shinfo->nr_frags = frag;
from->bvec += bi.bi_idx;
from->nr_segs -= bi.bi_idx;
from->count = bi.bi_size;
--
2.36.1
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