tcp: do not cache align timewait sockets

With recent adoption of skc_cookie in struct sock_common,
struct tcp_timewait_sock size increased from 192 to 200 bytes
on 64bit arches. SLAB rounds then to 256 bytes.

It is time to drop SLAB_HWCACHE_ALIGN constraint for twsk_slab.

This saves about 12 MB of memory on typical configuration reaching
262144 timewait sockets, and has no noticeable impact on performance.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/core/sock.c

@@ -2799,8 +2799,7 @@ int proto_register(struct proto *prot, int alloc_slab)
 				kmem_cache_create(prot->twsk_prot->twsk_slab_name,
 						  prot->twsk_prot->twsk_obj_size,
 						  0,
-						  SLAB_HWCACHE_ALIGN |
-							prot->slab_flags,
+						  prot->slab_flags,
 						  NULL);
 			if (prot->twsk_prot->twsk_slab == NULL)
 				goto out_free_timewait_sock_slab_name;