Re: [PATCH RFC] proc/meminfo: add NetBuffers counter for socket buffers

[Vlastimil Babka]

On 5/15/19 1:55 PM, Konstantin Khlebnikov wrote:
> Socket buffers always were dark-matter that lives by its own rules.

Is the information even exported somewhere e.g. in sysfs or via netlink yet?

> This patch adds line NetBuffers that exposes most common kinds of them.

Did you encounter a situation where the number was significant and this
would help finding out why memory is occupied?

> TCP and UDP are most important species.
> SCTP is added as example of modular protocol.
> UNIX have no memory counter for now, should be easy to add.
> 
> Signed-off-by: Konstantin Khlebnikov <khlebnikov@xxxxxxxxxxxxxx>

Right now it's a sum of a few values, which should be fine wrt
/proc/meminfo overhead. But I guess netdev guys should have a say in
this. Also you should update the corresponding Documentation/ file.

Thanks,
Vlastimil

> ---
>  fs/proc/meminfo.c  |    5 ++++-
>  include/linux/mm.h |    6 ++++++
>  mm/page_alloc.c    |    3 ++-
>  net/core/sock.c    |   20 ++++++++++++++++++++
>  net/sctp/socket.c  |    2 +-
>  5 files changed, 33 insertions(+), 3 deletions(-)
> 
> diff --git a/fs/proc/meminfo.c b/fs/proc/meminfo.c
> index 7bc14716fc5d..0ee2300a916d 100644
> --- a/fs/proc/meminfo.c
> +++ b/fs/proc/meminfo.c
> @@ -41,6 +41,7 @@ static int meminfo_proc_show(struct seq_file *m, void *v)
>  	unsigned long sreclaimable, sunreclaim, misc_reclaimable;
>  	unsigned long kernel_stack_kb, page_tables, percpu_pages;
>  	unsigned long anon_pages, file_pages, swap_cached;
> +	unsigned long net_buffers;
>  	long kernel_misc;
>  	int lru;
>  
> @@ -66,12 +67,13 @@ static int meminfo_proc_show(struct seq_file *m, void *v)
>  	kernel_stack_kb = global_zone_page_state(NR_KERNEL_STACK_KB);
>  	page_tables = global_zone_page_state(NR_PAGETABLE);
>  	percpu_pages = pcpu_nr_pages();
> +	net_buffers = total_netbuffer_pages();
>  
>  	/* all other kinds of kernel memory allocations */
>  	kernel_misc = i.totalram - i.freeram - anon_pages - file_pages
>  		      - sreclaimable - sunreclaim - misc_reclaimable
>  		      - (kernel_stack_kb >> (PAGE_SHIFT - 10))
> -		      - page_tables - percpu_pages;
> +		      - page_tables - percpu_pages - net_buffers;
>  	if (kernel_misc < 0)
>  		kernel_misc = 0;
>  
> @@ -137,6 +139,7 @@ static int meminfo_proc_show(struct seq_file *m, void *v)
>  	show_val_kb(m, "VmallocUsed:    ", 0ul);
>  	show_val_kb(m, "VmallocChunk:   ", 0ul);
>  	show_val_kb(m, "Percpu:         ", percpu_pages);
> +	show_val_kb(m, "NetBuffers:     ", net_buffers);
>  	show_val_kb(m, "KernelMisc:     ", kernel_misc);
>  
>  #ifdef CONFIG_MEMORY_FAILURE
> diff --git a/include/linux/mm.h b/include/linux/mm.h
> index 0e8834ac32b7..d0a58355bfb7 100644
> --- a/include/linux/mm.h
> +++ b/include/linux/mm.h
> @@ -2254,6 +2254,12 @@ extern void si_meminfo_node(struct sysinfo *val, int nid);
>  extern unsigned long arch_reserved_kernel_pages(void);
>  #endif
>  
> +#ifdef CONFIG_NET
> +extern unsigned long total_netbuffer_pages(void);
> +#else
> +static inline unsigned long total_netbuffer_pages(void) { return 0; }
> +#endif
> +
>  extern __printf(3, 4)
>  void warn_alloc(gfp_t gfp_mask, nodemask_t *nodemask, const char *fmt, ...);
>  
> diff --git a/mm/page_alloc.c b/mm/page_alloc.c
> index 3b13d3914176..fcdd7c6e72b9 100644
> --- a/mm/page_alloc.c
> +++ b/mm/page_alloc.c
> @@ -5166,7 +5166,7 @@ void show_free_areas(unsigned int filter, nodemask_t *nodemask)
>  		" active_file:%lu inactive_file:%lu isolated_file:%lu\n"
>  		" unevictable:%lu dirty:%lu writeback:%lu unstable:%lu\n"
>  		" slab_reclaimable:%lu slab_unreclaimable:%lu\n"
> -		" mapped:%lu shmem:%lu pagetables:%lu bounce:%lu\n"
> +		" mapped:%lu shmem:%lu pagetables:%lu bounce:%lu net_buffers:%lu\n"
>  		" free:%lu free_pcp:%lu free_cma:%lu\n",
>  		global_node_page_state(NR_ACTIVE_ANON),
>  		global_node_page_state(NR_INACTIVE_ANON),
> @@ -5184,6 +5184,7 @@ void show_free_areas(unsigned int filter, nodemask_t *nodemask)
>  		global_node_page_state(NR_SHMEM),
>  		global_zone_page_state(NR_PAGETABLE),
>  		global_zone_page_state(NR_BOUNCE),
> +		total_netbuffer_pages(),
>  		global_zone_page_state(NR_FREE_PAGES),
>  		free_pcp,
>  		global_zone_page_state(NR_FREE_CMA_PAGES));
> diff --git a/net/core/sock.c b/net/core/sock.c
> index 75b1c950b49f..dfca4e024b74 100644
> --- a/net/core/sock.c
> +++ b/net/core/sock.c
> @@ -142,6 +142,7 @@
>  #include <trace/events/sock.h>
>  
>  #include <net/tcp.h>
> +#include <net/udp.h>
>  #include <net/busy_poll.h>
>  
>  static DEFINE_MUTEX(proto_list_mutex);
> @@ -3573,3 +3574,22 @@ bool sk_busy_loop_end(void *p, unsigned long start_time)
>  }
>  EXPORT_SYMBOL(sk_busy_loop_end);
>  #endif /* CONFIG_NET_RX_BUSY_POLL */
> +
> +#if IS_ENABLED(CONFIG_IP_SCTP)
> +atomic_long_t sctp_memory_allocated;
> +EXPORT_SYMBOL_GPL(sctp_memory_allocated);
> +#endif
> +
> +unsigned long total_netbuffer_pages(void)
> +{
> +	unsigned long ret = 0;
> +
> +#if IS_ENABLED(CONFIG_IP_SCTP)
> +	ret += atomic_long_read(&sctp_memory_allocated);
> +#endif
> +#ifdef CONFIG_INET
> +	ret += atomic_long_read(&tcp_memory_allocated);
> +	ret += atomic_long_read(&udp_memory_allocated);
> +#endif
> +	return ret;
> +}
> diff --git a/net/sctp/socket.c b/net/sctp/socket.c
> index e4e892cc5644..9d11afdeeae4 100644
> --- a/net/sctp/socket.c
> +++ b/net/sctp/socket.c
> @@ -107,7 +107,7 @@ static int sctp_sock_migrate(struct sock *oldsk, struct sock *newsk,
>  			     enum sctp_socket_type type);
>  
>  static unsigned long sctp_memory_pressure;
> -static atomic_long_t sctp_memory_allocated;
> +extern atomic_long_t sctp_memory_allocated;
>  struct percpu_counter sctp_sockets_allocated;
>  
>  static void sctp_enter_memory_pressure(struct sock *sk)
>