diff mbox series

[net-next,v2] ipv6: remove max_size check inline with ipv4

Message ID 20230112012532.311021-1-jmaxwell37@gmail.com (mailing list archive)
State Accepted
Commit af6d10345ca76670c1b7c37799f0d5576ccef277
Delegated to: Netdev Maintainers
Headers show
Series [net-next,v2] ipv6: remove max_size check inline with ipv4 | expand

Checks

Context Check Description
netdev/tree_selection success Clearly marked for net-next
netdev/fixes_present success Fixes tag not required for -next series
netdev/subject_prefix success Link
netdev/cover_letter success Single patches do not need cover letters
netdev/patch_count success Link
netdev/header_inline success No static functions without inline keyword in header files
netdev/build_32bit success Errors and warnings before: 4555 this patch: 4555
netdev/cc_maintainers success CCed 12 of 12 maintainers
netdev/build_clang success Errors and warnings before: 1072 this patch: 1072
netdev/module_param success Was 0 now: 0
netdev/verify_signedoff success Signed-off-by tag matches author and committer
netdev/check_selftest success No net selftest shell script
netdev/verify_fixes success No Fixes tag
netdev/build_allmodconfig_warn success Errors and warnings before: 4764 this patch: 4764
netdev/checkpatch warning WARNING: Commit log lines starting with '#' are dropped by git as comments
netdev/kdoc success Errors and warnings before: 0 this patch: 0
netdev/source_inline success Was 0 now: 0

Commit Message

Jonathan Maxwell Jan. 12, 2023, 1:25 a.m. UTC 
v2: Correct syntax error in net/ipv6/route.c

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:

# ./a.out -s 

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:

# grep -e Slab -e Free /proc/meminfo
MemFree:        29427108 kB
Slab:             237612 kB

# grep dst_cache /proc/slabinfo
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:

# grep -e Slab -e Free /proc/meminfo
MemFree:        29417608 kB
Slab:             247712 kB

# grep dst_cache /proc/slabinfo
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:

# grep -e Slab -e Free /proc/meminfo
MemFree:        29422308 kB
Slab:             238104 kB

# grep dst_cache /proc/slabinfo
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:

# grep -e Slab -e Free /proc/meminfo
MemFree:        29422308 kB
Slab:             238104 kB

# grep dst_cache /proc/slabinfo
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:

# grep -e Slab -e Free /proc/meminfo
MemFree:        29431516 kB
Slab:             240940 kB

# grep dst_cache /proc/slabinfo
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:

# grep -e Slab -e Free /proc/meminfo
MemFree:        29441816 kB
Slab:             238132 kB

# grep dst_cache /proc/slabinfo
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@uniroma2.it>
Signed-off-by: Jon Maxwell <jmaxwell37@gmail.com>
---
 include/net/dst_ops.h |  2 +-
 net/core/dst.c        |  8 ++------
 net/ipv6/route.c      | 13 +++++--------
 3 files changed, 8 insertions(+), 15 deletions(-)

Comments

Andrea Mayer Jan. 12, 2023, 8:41 p.m. UTC | #1 
Hi Jon,

On Thu, 12 Jan 2023 12:25:32 +1100
Jon Maxwell <jmaxwell37@gmail.com> wrote:

> v2: Correct syntax error in net/ipv6/route.c
> 
> 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:
> 
> # ./a.out -s 
> 
> 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: 
> 

is it supposed to be Ipv6, right?

Ciao,
Andrea

> Before test:
> 
> # grep -e Slab -e Free /proc/meminfo
> MemFree:        29427108 kB
> Slab:             237612 kB
> 
> # grep dst_cache /proc/slabinfo
> 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:
> 
> # grep -e Slab -e Free /proc/meminfo
> MemFree:        29417608 kB
> Slab:             247712 kB
> 
> # grep dst_cache /proc/slabinfo
> 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:
> 
> # grep -e Slab -e Free /proc/meminfo
> MemFree:        29422308 kB
> Slab:             238104 kB
> 
> # grep dst_cache /proc/slabinfo
> 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:
> 
> # grep -e Slab -e Free /proc/meminfo
> MemFree:        29422308 kB
> Slab:             238104 kB
> 
> # grep dst_cache /proc/slabinfo
> 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:
> 
> # grep -e Slab -e Free /proc/meminfo
> MemFree:        29431516 kB
> Slab:             240940 kB
> 
> # grep dst_cache /proc/slabinfo
> 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:
> 
> # grep -e Slab -e Free /proc/meminfo
> MemFree:        29441816 kB
> Slab:             238132 kB
> 
> # grep dst_cache /proc/slabinfo
> 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@uniroma2.it>
> Signed-off-by: Jon Maxwell <jmaxwell37@gmail.com>
> ---
>  include/net/dst_ops.h |  2 +-
>  net/core/dst.c        |  8 ++------
>  net/ipv6/route.c      | 13 +++++--------
>  3 files changed, 8 insertions(+), 15 deletions(-)
> 
> diff --git a/include/net/dst_ops.h b/include/net/dst_ops.h
> index 88ff7bb2bb9b..632086b2f644 100644
> --- 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 *);
> diff --git a/net/core/dst.c b/net/core/dst.c
> index 6d2dd03dafa8..31c08a3386d3 100644
> --- a/net/core/dst.c
> +++ b/net/core/dst.c
> @@ -82,12 +82,8 @@ void *dst_alloc(struct dst_ops *ops, struct net_device *dev,
>  
>  	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)
> diff --git a/net/ipv6/route.c b/net/ipv6/route.c
> index e74e0361fd92..b643dda68d31 100644
> --- a/net/ipv6/route.c
> +++ b/net/ipv6/route.c
> @@ -91,7 +91,7 @@ static struct dst_entry *ip6_negative_advice(struct dst_entry *);
>  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);
> @@ -3284,11 +3284,10 @@ struct dst_entry *icmp6_dst_alloc(struct net_device *dev,
>  	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;
> @@ -3296,11 +3295,10 @@ static int ip6_dst_gc(struct dst_ops *ops)
>  	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);
> @@ -3310,7 +3308,6 @@ static int ip6_dst_gc(struct dst_ops *ops)
>  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,
> @@ -6512,7 +6509,7 @@ static int __net_init ip6_route_net_init(struct net *net)
>  #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;
> -- 
> 2.31.1
Jonathan Maxwell Jan. 12, 2023, 9:48 p.m. UTC | #2 
Hi Andrea,

On Fri, Jan 13, 2023 at 7:41 AM Andrea Mayer <andrea.mayer@uniroma2.it> wrote:
>
> Hi Jon,
>
> On Thu, 12 Jan 2023 12:25:32 +1100
> Jon Maxwell <jmaxwell37@gmail.com> wrote:
>
> > v2: Correct syntax error in net/ipv6/route.c
> >
> > 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:
> >
> > # ./a.out -s
> >
> > 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:
> >
>
> is it supposed to be Ipv6, right?
>

No, That is for Ipv4, DavidA asked me to include a comparison between Ipv4
and Ipv6.  So that is taken for a test running 5 processes that sends 5000000
packets on  an ipv4 raw socket. If you scroll down, Ipv6 memory statistics
are under "Ipv6 with patch:".

Regards

Jon

> Ciao,
> Andrea
>
> > Before test:
> >
> > # grep -e Slab -e Free /proc/meminfo
> > MemFree:        29427108 kB
> > Slab:             237612 kB
> >
> > # grep dst_cache /proc/slabinfo
> > 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:
> >
> > # grep -e Slab -e Free /proc/meminfo
> > MemFree:        29417608 kB
> > Slab:             247712 kB
> >
> > # grep dst_cache /proc/slabinfo
> > 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:
> >
> > # grep -e Slab -e Free /proc/meminfo
> > MemFree:        29422308 kB
> > Slab:             238104 kB
> >
> > # grep dst_cache /proc/slabinfo
> > 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:
> >
> > # grep -e Slab -e Free /proc/meminfo
> > MemFree:        29422308 kB
> > Slab:             238104 kB
> >
> > # grep dst_cache /proc/slabinfo
> > 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:
> >
> > # grep -e Slab -e Free /proc/meminfo
> > MemFree:        29431516 kB
> > Slab:             240940 kB
> >
> > # grep dst_cache /proc/slabinfo
> > 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:
> >
> > # grep -e Slab -e Free /proc/meminfo
> > MemFree:        29441816 kB
> > Slab:             238132 kB
> >
> > # grep dst_cache /proc/slabinfo
> > 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@uniroma2.it>
> > Signed-off-by: Jon Maxwell <jmaxwell37@gmail.com>
> > ---
> >  include/net/dst_ops.h |  2 +-
> >  net/core/dst.c        |  8 ++------
> >  net/ipv6/route.c      | 13 +++++--------
> >  3 files changed, 8 insertions(+), 15 deletions(-)
> >
> > diff --git a/include/net/dst_ops.h b/include/net/dst_ops.h
> > index 88ff7bb2bb9b..632086b2f644 100644
> > --- 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 *);
> > diff --git a/net/core/dst.c b/net/core/dst.c
> > index 6d2dd03dafa8..31c08a3386d3 100644
> > --- a/net/core/dst.c
> > +++ b/net/core/dst.c
> > @@ -82,12 +82,8 @@ void *dst_alloc(struct dst_ops *ops, struct net_device *dev,
> >
> >       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)
> > diff --git a/net/ipv6/route.c b/net/ipv6/route.c
> > index e74e0361fd92..b643dda68d31 100644
> > --- a/net/ipv6/route.c
> > +++ b/net/ipv6/route.c
> > @@ -91,7 +91,7 @@ static struct dst_entry *ip6_negative_advice(struct dst_entry *);
> >  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);
> > @@ -3284,11 +3284,10 @@ struct dst_entry *icmp6_dst_alloc(struct net_device *dev,
> >       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;
> > @@ -3296,11 +3295,10 @@ static int ip6_dst_gc(struct dst_ops *ops)
> >       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);
> > @@ -3310,7 +3308,6 @@ static int ip6_dst_gc(struct dst_ops *ops)
> >  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,
> > @@ -6512,7 +6509,7 @@ static int __net_init ip6_route_net_init(struct net *net)
> >  #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;
> > --
> > 2.31.1
Andrea Mayer Jan. 12, 2023, 10:26 p.m. UTC | #3 
On Fri, 13 Jan 2023 08:48:24 +1100
Jonathan Maxwell <jmaxwell37@gmail.com> wrote:

> Hi Andrea,
> 
> On Fri, Jan 13, 2023 at 7:41 AM Andrea Mayer <andrea.mayer@uniroma2.it> wrote:
> >
> > Hi Jon,
> >
> > On Thu, 12 Jan 2023 12:25:32 +1100
> > Jon Maxwell <jmaxwell37@gmail.com> wrote:
> >
> > > v2: Correct syntax error in net/ipv6/route.c
> > >
> > > 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:
> > >
> > > # ./a.out -s
> > >
> > > 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:
> > >
> >
> > is it supposed to be Ipv6, right?
> >
> 
> No, That is for Ipv4, DavidA asked me to include a comparison between Ipv4
> and Ipv6.  So that is taken for a test running 5 processes that sends 5000000
> packets on  an ipv4 raw socket. If you scroll down, Ipv6 memory statistics
> are under "Ipv6 with patch:".
> 

I asked because these tests also report ip6_dst_cache counters that I would not
have expected to find in IPv4 cases (and viceversa).

Thanks for the clarification.

Ciao,
Andrea

> Regards
> 
> Jon
> 
> > Ciao,
> > Andrea
> >
> > > Before test:
> > >
> > > # grep -e Slab -e Free /proc/meminfo
> > > MemFree:        29427108 kB
> > > Slab:             237612 kB
> > >
> > > # grep dst_cache /proc/slabinfo
> > > 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:
> > >
> > > # grep -e Slab -e Free /proc/meminfo
> > > MemFree:        29417608 kB
> > > Slab:             247712 kB
> > >
> > > # grep dst_cache /proc/slabinfo
> > > 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:
> > >
> > > # grep -e Slab -e Free /proc/meminfo
> > > MemFree:        29422308 kB
> > > Slab:             238104 kB
> > >
> > > # grep dst_cache /proc/slabinfo
> > > 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:
> > >
> > > # grep -e Slab -e Free /proc/meminfo
> > > MemFree:        29422308 kB
> > > Slab:             238104 kB
> > >
> > > # grep dst_cache /proc/slabinfo
> > > 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:
> > >
> > > # grep -e Slab -e Free /proc/meminfo
> > > MemFree:        29431516 kB
> > > Slab:             240940 kB
> > >
> > > # grep dst_cache /proc/slabinfo
> > > 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:
> > >
> > > # grep -e Slab -e Free /proc/meminfo
> > > MemFree:        29441816 kB
> > > Slab:             238132 kB
> > >
> > > # grep dst_cache /proc/slabinfo
> > > 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@uniroma2.it>
> > > Signed-off-by: Jon Maxwell <jmaxwell37@gmail.com>
> > > ---
> > >  include/net/dst_ops.h |  2 +-
> > >  net/core/dst.c        |  8 ++------
> > >  net/ipv6/route.c      | 13 +++++--------
> > >  3 files changed, 8 insertions(+), 15 deletions(-)
> > >
> > > diff --git a/include/net/dst_ops.h b/include/net/dst_ops.h
> > > index 88ff7bb2bb9b..632086b2f644 100644
> > > --- 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 *);
> > > diff --git a/net/core/dst.c b/net/core/dst.c
> > > index 6d2dd03dafa8..31c08a3386d3 100644
> > > --- a/net/core/dst.c
> > > +++ b/net/core/dst.c
> > > @@ -82,12 +82,8 @@ void *dst_alloc(struct dst_ops *ops, struct net_device *dev,
> > >
> > >       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)
> > > diff --git a/net/ipv6/route.c b/net/ipv6/route.c
> > > index e74e0361fd92..b643dda68d31 100644
> > > --- a/net/ipv6/route.c
> > > +++ b/net/ipv6/route.c
> > > @@ -91,7 +91,7 @@ static struct dst_entry *ip6_negative_advice(struct dst_entry *);
> > >  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);
> > > @@ -3284,11 +3284,10 @@ struct dst_entry *icmp6_dst_alloc(struct net_device *dev,
> > >       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;
> > > @@ -3296,11 +3295,10 @@ static int ip6_dst_gc(struct dst_ops *ops)
> > >       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);
> > > @@ -3310,7 +3308,6 @@ static int ip6_dst_gc(struct dst_ops *ops)
> > >  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,
> > > @@ -6512,7 +6509,7 @@ static int __net_init ip6_route_net_init(struct net *net)
> > >  #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;
> > > --
> > > 2.31.1
David Ahern Jan. 13, 2023, 4:03 a.m. UTC | #4 
On 1/11/23 6:25 PM, Jon Maxwell wrote:
> v2: Correct syntax error in net/ipv6/route.c
> 
> 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:
> 
> # ./a.out -s 
> 
> 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:
> 
> # grep -e Slab -e Free /proc/meminfo
> MemFree:        29427108 kB
> Slab:             237612 kB
> 
> # grep dst_cache /proc/slabinfo
> 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:
> 
> # grep -e Slab -e Free /proc/meminfo
> MemFree:        29417608 kB
> Slab:             247712 kB
> 
> # grep dst_cache /proc/slabinfo
> 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:
> 
> # grep -e Slab -e Free /proc/meminfo
> MemFree:        29422308 kB
> Slab:             238104 kB
> 
> # grep dst_cache /proc/slabinfo
> 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:
> 
> # grep -e Slab -e Free /proc/meminfo
> MemFree:        29422308 kB
> Slab:             238104 kB
> 
> # grep dst_cache /proc/slabinfo
> 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:
> 
> # grep -e Slab -e Free /proc/meminfo
> MemFree:        29431516 kB
> Slab:             240940 kB
> 
> # grep dst_cache /proc/slabinfo
> 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:
> 
> # grep -e Slab -e Free /proc/meminfo
> MemFree:        29441816 kB
> Slab:             238132 kB
> 
> # grep dst_cache /proc/slabinfo
> 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@uniroma2.it>
> Signed-off-by: Jon Maxwell <jmaxwell37@gmail.com>
> ---
>  include/net/dst_ops.h |  2 +-
>  net/core/dst.c        |  8 ++------
>  net/ipv6/route.c      | 13 +++++--------
>  3 files changed, 8 insertions(+), 15 deletions(-)
> 

Thanks for the data in the commit message.

Reviewed-by: David Ahern <dsahern@kernel.org>
patchwork-bot+netdevbpf@kernel.org Jan. 14, 2023, 5:40 a.m. UTC | #5 
Hello:

This patch was applied to netdev/net-next.git (master)
by Jakub Kicinski <kuba@kernel.org>:

On Thu, 12 Jan 2023 12:25:32 +1100 you wrote:
> v2: Correct syntax error in net/ipv6/route.c
> 
> In ip6_dst_gc() replace:
> 
> if (entries > gc_thresh)
> 
> With:
> 
> [...]

Here is the summary with links:
  - [net-next,v2] ipv6: remove max_size check inline with ipv4
    https://git.kernel.org/netdev/net-next/c/af6d10345ca7

You are awesome, thank you!
diff mbox series

Patch

diff --git a/include/net/dst_ops.h b/include/net/dst_ops.h
index 88ff7bb2bb9b..632086b2f644 100644
--- 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 *);
diff --git a/net/core/dst.c b/net/core/dst.c
index 6d2dd03dafa8..31c08a3386d3 100644
--- a/net/core/dst.c
+++ b/net/core/dst.c
@@ -82,12 +82,8 @@  void *dst_alloc(struct dst_ops *ops, struct net_device *dev,
 
 	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)
diff --git a/net/ipv6/route.c b/net/ipv6/route.c
index e74e0361fd92..b643dda68d31 100644
--- a/net/ipv6/route.c
+++ b/net/ipv6/route.c
@@ -91,7 +91,7 @@  static struct dst_entry *ip6_negative_advice(struct dst_entry *);
 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);
@@ -3284,11 +3284,10 @@  struct dst_entry *icmp6_dst_alloc(struct net_device *dev,
 	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;
@@ -3296,11 +3295,10 @@  static int ip6_dst_gc(struct dst_ops *ops)
 	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);
@@ -3310,7 +3308,6 @@  static int ip6_dst_gc(struct dst_ops *ops)
 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,
@@ -6512,7 +6509,7 @@  static int __net_init ip6_route_net_init(struct net *net)
 #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;