Messages in this thread Patch in this message | | | From | Tahsin Erdogan <> | Subject | [PATCH v3] tun: avoid high-order page allocation for packet header | Date | Tue, 8 Aug 2023 16:09:19 -0700 |
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When GSO is not enabled and a packet is transmitted via writev(), all payload is treated as header which requires a contiguous memory allocation. This allocation request is harder to satisfy, and may even fail if there is enough fragmentation.
Note that sendmsg() code path limits the linear copy length, so this change makes writev() and sendmsg() more consistent.
Signed-off-by: Tahsin Erdogan <trdgn@amazon.com> --- v3: rebase to latest net-next v2: replace linear == 0 with !linear v1: https://lore.kernel.org/all/20230726030936.1587269-1-trdgn@amazon.com/ drivers/net/tun.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-)
diff --git a/drivers/net/tun.c b/drivers/net/tun.c index 5beb6b5dd7e5..53d19c958a20 100644 --- a/drivers/net/tun.c +++ b/drivers/net/tun.c @@ -1523,7 +1523,7 @@ static struct sk_buff *tun_alloc_skb(struct tun_file *tfile, int err; /* Under a page? Don't bother with paged skb. */ - if (prepad + len < PAGE_SIZE || !linear) + if (prepad + len < PAGE_SIZE) linear = len; if (len - linear > MAX_SKB_FRAGS * (PAGE_SIZE << PAGE_ALLOC_COSTLY_ORDER)) @@ -1913,6 +1913,9 @@ static ssize_t tun_get_user(struct tun_struct *tun, struct tun_file *tfile, */ zerocopy = false; } else { + if (!linear) + linear = min_t(size_t, good_linear, copylen); + skb = tun_alloc_skb(tfile, align, copylen, linear, noblock); } -- 2.41.0
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