[PATCH net-next] ipvs: dynamically limit the connection hash table

[Julian Anastasov <ja@xxxxxx>]

As we allow the hash table to be configured to rows above 2^20,
we should limit it depending on the available memory to some
sane values. Switch to kvmalloc allocation to better select
the needed allocation type.

Signed-off-by: Julian Anastasov <ja@xxxxxx>
---
 net/netfilter/ipvs/ip_vs_conn.c | 26 +++++++++++++++++---------
 1 file changed, 17 insertions(+), 9 deletions(-)

 NOTE: This patch needs to be applied on top of V3 (or above) of patch
 "ipvs: increase ip_vs_conn_tab_bits range for 64BIT" from Abhijeet

diff --git a/net/netfilter/ipvs/ip_vs_conn.c b/net/netfilter/ipvs/ip_vs_conn.c
index f4c55e65abd1..79d7ae8e50e5 100644
--- a/net/netfilter/ipvs/ip_vs_conn.c
+++ b/net/netfilter/ipvs/ip_vs_conn.c
@@ -26,7 +26,6 @@
 #include <linux/net.h>
 #include <linux/kernel.h>
 #include <linux/module.h>
-#include <linux/vmalloc.h>
 #include <linux/proc_fs.h>             /* for proc_net_* */
 #include <linux/slab.h>
 #include <linux/seq_file.h>
@@ -1482,13 +1481,21 @@ void __net_exit ip_vs_conn_net_cleanup(struct 
netns_ipvs *ipvs)
 int __init ip_vs_conn_init(void)
 {
        size_t tab_array_size;
+       int max_avail;
+#if BITS_PER_LONG > 32
+       int max = 27;
+#else
+       int max = 20;
+#endif
+       int min = 8;
        int idx;
 
-       /* Compute size and mask */
-       if (ip_vs_conn_tab_bits < 8 || ip_vs_conn_tab_bits > 27) {
-               pr_info("conn_tab_bits not in [8, 27]. Using default value\n");
-               ip_vs_conn_tab_bits = CONFIG_IP_VS_TAB_BITS;
-       }
+       max_avail = order_base_2(totalram_pages()) + PAGE_SHIFT;
+       max_avail -= 2;         /* ~4 in hash row */
+       max_avail -= 1;         /* IPVS up to 1/2 of mem */
+       max_avail -= order_base_2(sizeof(struct ip_vs_conn));
+       max = clamp(max, min, max_avail);
+       ip_vs_conn_tab_bits = clamp_val(ip_vs_conn_tab_bits, min, max);
        ip_vs_conn_tab_size = 1 << ip_vs_conn_tab_bits;
        ip_vs_conn_tab_mask = ip_vs_conn_tab_size - 1;
 
@@ -1497,7 +1504,8 @@ int __init ip_vs_conn_init(void)
         */
        tab_array_size = array_size(ip_vs_conn_tab_size,
                                    sizeof(*ip_vs_conn_tab));
-       ip_vs_conn_tab = vmalloc(tab_array_size);
+       ip_vs_conn_tab = kvmalloc_array(ip_vs_conn_tab_size,
+                                       sizeof(*ip_vs_conn_tab), GFP_KERNEL);
        if (!ip_vs_conn_tab)
                return -ENOMEM;
 
@@ -1506,7 +1514,7 @@ int __init ip_vs_conn_init(void)
                                              sizeof(struct ip_vs_conn), 0,
                                              SLAB_HWCACHE_ALIGN, NULL);
        if (!ip_vs_conn_cachep) {
-               vfree(ip_vs_conn_tab);
+               kvfree(ip_vs_conn_tab);
                return -ENOMEM;
        }
 
@@ -1534,5 +1542,5 @@ void ip_vs_conn_cleanup(void)
        rcu_barrier();
        /* Release the empty cache */
        kmem_cache_destroy(ip_vs_conn_cachep);
-       vfree(ip_vs_conn_tab);
+       kvfree(ip_vs_conn_tab);
 }
-- 
2.40.1