3.16.57-rc1 review patch. If anyone has any objections, please let me know.
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From: Alexey Kodanev alexey.kodanev@oracle.com
commit 35d889d10b649fda66121891ec05eca88150059d upstream.
When we exceed current packets limit and we have more than one segment in the list returned by skb_gso_segment(), netem drops only the first one, skipping the rest, hence kmemleak reports:
unreferenced object 0xffff880b5d23b600 (size 1024): comm "softirq", pid 0, jiffies 4384527763 (age 2770.629s) hex dump (first 32 bytes): 00 80 23 5d 0b 88 ff ff 00 00 00 00 00 00 00 00 ..#]............ 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ backtrace: [<00000000d8a19b9d>] __alloc_skb+0xc9/0x520 [<000000001709b32f>] skb_segment+0x8c8/0x3710 [<00000000c7b9bb88>] tcp_gso_segment+0x331/0x1830 [<00000000c921cba1>] inet_gso_segment+0x476/0x1370 [<000000008b762dd4>] skb_mac_gso_segment+0x1f9/0x510 [<000000002182660a>] __skb_gso_segment+0x1dd/0x620 [<00000000412651b9>] netem_enqueue+0x1536/0x2590 [sch_netem] [<0000000005d3b2a9>] __dev_queue_xmit+0x1167/0x2120 [<00000000fc5f7327>] ip_finish_output2+0x998/0xf00 [<00000000d309e9d3>] ip_output+0x1aa/0x2c0 [<000000007ecbd3a4>] tcp_transmit_skb+0x18db/0x3670 [<0000000042d2a45f>] tcp_write_xmit+0x4d4/0x58c0 [<0000000056a44199>] tcp_tasklet_func+0x3d9/0x540 [<0000000013d06d02>] tasklet_action+0x1ca/0x250 [<00000000fcde0b8b>] __do_softirq+0x1b4/0x5a3 [<00000000e7ed027c>] irq_exit+0x1e2/0x210
Fix it by adding the rest of the segments, if any, to skb 'to_free' list. Add new __qdisc_drop_all() and qdisc_drop_all() functions because they can be useful in the future if we need to drop segmented GSO packets in other places.
Fixes: 6071bd1aa13e ("netem: Segment GSO packets on enqueue") Signed-off-by: Alexey Kodanev alexey.kodanev@oracle.com Acked-by: Neil Horman nhorman@tuxdriver.com Signed-off-by: David S. Miller davem@davemloft.net [bwh: Backported to 3.16: - The reshape_fail operation still exists, so keep calling it here if the skb did not require segmentation - We don't have a to_free list, so free directly in qdisc_drop_all() - Open-code qdisc_qstats_drop()] Signed-off-by: Ben Hutchings ben@decadent.org.uk --- --- a/include/net/sch_generic.h +++ b/include/net/sch_generic.h @@ -656,6 +656,14 @@ static inline int qdisc_drop(struct sk_b return NET_XMIT_DROP; }
+static inline int qdisc_drop_all(struct sk_buff *skb, struct Qdisc *sch) +{ + kfree_skb_list(skb); + sch->qstats.drops++; + + return NET_XMIT_DROP; +} + static inline int qdisc_reshape_fail(struct sk_buff *skb, struct Qdisc *sch) { sch->qstats.drops++; --- a/net/sched/sch_netem.c +++ b/net/sched/sch_netem.c @@ -511,8 +511,12 @@ static int netem_enqueue(struct sk_buff 1<<(prandom_u32() % 8); }
- if (unlikely(skb_queue_len(&sch->q) >= sch->limit)) + if (unlikely(skb_queue_len(&sch->q) >= sch->limit)) { + /* qdisc_reshape_fail() can't handle segmented skb */ + if (segs) + return qdisc_drop_all(skb, sch); return qdisc_reshape_fail(skb, sch); + }
sch->qstats.backlog += qdisc_pkt_len(skb);