This is a note to let you know that I've just added the patch titled
ipv6: remove max_size check inline with ipv4
to the 5.15-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
ipv6-remove-max_size-check-inline-with-ipv4.patch
and it can be found in the queue-5.15 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From af6d10345ca76670c1b7c37799f0d5576ccef277 Mon Sep 17 00:00:00 2001
From: Jon Maxwell <jmaxwell37@xxxxxxxxx>
Date: Thu, 12 Jan 2023 12:25:32 +1100
Subject: ipv6: remove max_size check inline with ipv4
From: Jon Maxwell <jmaxwell37@xxxxxxxxx>
commit af6d10345ca76670c1b7c37799f0d5576ccef277 upstream.
In ip6_dst_gc() replace:
if (entries > gc_thresh)
With:
if (entries > ops->gc_thresh)
Sending Ipv6 packets in a loop via a raw socket triggers an issue where a
route is cloned by ip6_rt_cache_alloc() for each packet sent. This quickly
consumes the Ipv6 max_size threshold which defaults to 4096 resulting in
these warnings:
[1] 99.187805] dst_alloc: 7728 callbacks suppressed
[2] Route cache is full: consider increasing sysctl net.ipv6.route.max_size.
.
.
[300] Route cache is full: consider increasing sysctl net.ipv6.route.max_size.
When this happens the packet is dropped and sendto() gets a network is
unreachable error:
remaining pkt 200557 errno 101
remaining pkt 196462 errno 101
.
.
remaining pkt 126821 errno 101
Implement David Aherns suggestion to remove max_size check seeing that Ipv6
has a GC to manage memory usage. Ipv4 already does not check max_size.
Here are some memory comparisons for Ipv4 vs Ipv6 with the patch:
Test by running 5 instances of a program that sends UDP packets to a raw
socket 5000000 times. Compare Ipv4 and Ipv6 performance with a similar
program.
Ipv4:
Before test:
MemFree: 29427108 kB
Slab: 237612 kB
ip6_dst_cache 1912 2528 256 32 2 : tunables 0 0 0
xfrm_dst_cache 0 0 320 25 2 : tunables 0 0 0
ip_dst_cache 2881 3990 192 42 2 : tunables 0 0 0
During test:
MemFree: 29417608 kB
Slab: 247712 kB
ip6_dst_cache 1912 2528 256 32 2 : tunables 0 0 0
xfrm_dst_cache 0 0 320 25 2 : tunables 0 0 0
ip_dst_cache 44394 44394 192 42 2 : tunables 0 0 0
After test:
MemFree: 29422308 kB
Slab: 238104 kB
ip6_dst_cache 1912 2528 256 32 2 : tunables 0 0 0
xfrm_dst_cache 0 0 320 25 2 : tunables 0 0 0
ip_dst_cache 3048 4116 192 42 2 : tunables 0 0 0
Ipv6 with patch:
Errno 101 errors are not observed anymore with the patch.
Before test:
MemFree: 29422308 kB
Slab: 238104 kB
ip6_dst_cache 1912 2528 256 32 2 : tunables 0 0 0
xfrm_dst_cache 0 0 320 25 2 : tunables 0 0 0
ip_dst_cache 3048 4116 192 42 2 : tunables 0 0 0
During Test:
MemFree: 29431516 kB
Slab: 240940 kB
ip6_dst_cache 11980 12064 256 32 2 : tunables 0 0 0
xfrm_dst_cache 0 0 320 25 2 : tunables 0 0 0
ip_dst_cache 3048 4116 192 42 2 : tunables 0 0 0
After Test:
MemFree: 29441816 kB
Slab: 238132 kB
ip6_dst_cache 1902 2432 256 32 2 : tunables 0 0 0
xfrm_dst_cache 0 0 320 25 2 : tunables 0 0 0
ip_dst_cache 3048 4116 192 42 2 : tunables 0 0 0
Tested-by: Andrea Mayer <andrea.mayer@xxxxxxxxxxx>
Signed-off-by: Jon Maxwell <jmaxwell37@xxxxxxxxx>
Reviewed-by: David Ahern <dsahern@xxxxxxxxxx>
Link: https://lore.kernel.org/r/20230112012532.311021-1-jmaxwell37@xxxxxxxxx
Signed-off-by: Jakub Kicinski <kuba@xxxxxxxxxx>
Cc: "Jitindar Singh, Suraj" <surajjs@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
include/net/dst_ops.h | 2 +-
net/core/dst.c | 8 ++------
net/ipv6/route.c | 13 +++++--------
3 files changed, 8 insertions(+), 15 deletions(-)
--- a/include/net/dst_ops.h
+++ b/include/net/dst_ops.h
@@ -16,7 +16,7 @@ struct dst_ops {
unsigned short family;
unsigned int gc_thresh;
- int (*gc)(struct dst_ops *ops);
+ void (*gc)(struct dst_ops *ops);
struct dst_entry * (*check)(struct dst_entry *, __u32 cookie);
unsigned int (*default_advmss)(const struct dst_entry *);
unsigned int (*mtu)(const struct dst_entry *);
--- a/net/core/dst.c
+++ b/net/core/dst.c
@@ -82,12 +82,8 @@ void *dst_alloc(struct dst_ops *ops, str
if (ops->gc &&
!(flags & DST_NOCOUNT) &&
- dst_entries_get_fast(ops) > ops->gc_thresh) {
- if (ops->gc(ops)) {
- pr_notice_ratelimited("Route cache is full: consider increasing sysctl net.ipv6.route.max_size.\n");
- return NULL;
- }
- }
+ dst_entries_get_fast(ops) > ops->gc_thresh)
+ ops->gc(ops);
dst = kmem_cache_alloc(ops->kmem_cachep, GFP_ATOMIC);
if (!dst)
--- a/net/ipv6/route.c
+++ b/net/ipv6/route.c
@@ -91,7 +91,7 @@ static struct dst_entry *ip6_negative_ad
static void ip6_dst_destroy(struct dst_entry *);
static void ip6_dst_ifdown(struct dst_entry *,
struct net_device *dev, int how);
-static int ip6_dst_gc(struct dst_ops *ops);
+static void ip6_dst_gc(struct dst_ops *ops);
static int ip6_pkt_discard(struct sk_buff *skb);
static int ip6_pkt_discard_out(struct net *net, struct sock *sk, struct sk_buff *skb);
@@ -3295,11 +3295,10 @@ out:
return dst;
}
-static int ip6_dst_gc(struct dst_ops *ops)
+static void ip6_dst_gc(struct dst_ops *ops)
{
struct net *net = container_of(ops, struct net, ipv6.ip6_dst_ops);
int rt_min_interval = net->ipv6.sysctl.ip6_rt_gc_min_interval;
- int rt_max_size = net->ipv6.sysctl.ip6_rt_max_size;
int rt_elasticity = net->ipv6.sysctl.ip6_rt_gc_elasticity;
int rt_gc_timeout = net->ipv6.sysctl.ip6_rt_gc_timeout;
unsigned long rt_last_gc = net->ipv6.ip6_rt_last_gc;
@@ -3307,11 +3306,10 @@ static int ip6_dst_gc(struct dst_ops *op
int entries;
entries = dst_entries_get_fast(ops);
- if (entries > rt_max_size)
+ if (entries > ops->gc_thresh)
entries = dst_entries_get_slow(ops);
- if (time_after(rt_last_gc + rt_min_interval, jiffies) &&
- entries <= rt_max_size)
+ if (time_after(rt_last_gc + rt_min_interval, jiffies))
goto out;
fib6_run_gc(atomic_inc_return(&net->ipv6.ip6_rt_gc_expire), net, true);
@@ -3321,7 +3319,6 @@ static int ip6_dst_gc(struct dst_ops *op
out:
val = atomic_read(&net->ipv6.ip6_rt_gc_expire);
atomic_set(&net->ipv6.ip6_rt_gc_expire, val - (val >> rt_elasticity));
- return entries > rt_max_size;
}
static int ip6_nh_lookup_table(struct net *net, struct fib6_config *cfg,
@@ -6528,7 +6525,7 @@ static int __net_init ip6_route_net_init
#endif
net->ipv6.sysctl.flush_delay = 0;
- net->ipv6.sysctl.ip6_rt_max_size = 4096;
+ net->ipv6.sysctl.ip6_rt_max_size = INT_MAX;
net->ipv6.sysctl.ip6_rt_gc_min_interval = HZ / 2;
net->ipv6.sysctl.ip6_rt_gc_timeout = 60*HZ;
net->ipv6.sysctl.ip6_rt_gc_interval = 30*HZ;
Patches currently in stable-queue which might be from jmaxwell37@xxxxxxxxx are
queue-5.15/ipv6-remove-max_size-check-inline-with-ipv4.patch
