net: fix sk_mem_reclaim_partial()

sk_mem_reclaim_partial() goal is to ensure each socket has
one SK_MEM_QUANTUM forward allocation. This is needed both for
performance and better handling of memory pressure situations in
follow up patches.

SK_MEM_QUANTUM is currently a page, but might be reduced to 4096 bytes
as some arches have 64KB pages.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/include/net/sock.h b/include/net/sock.h
index d882f4c..4581a60 100644
--- a/include/net/sock.h
+++ b/include/net/sock.h
@@ -1368,7 +1368,7 @@
  * Functions for memory accounting
  */
 int __sk_mem_schedule(struct sock *sk, int size, int kind);
-void __sk_mem_reclaim(struct sock *sk);
+void __sk_mem_reclaim(struct sock *sk, int amount);
 
 #define SK_MEM_QUANTUM ((int)PAGE_SIZE)
 #define SK_MEM_QUANTUM_SHIFT ilog2(SK_MEM_QUANTUM)
@@ -1409,7 +1409,7 @@
 	if (!sk_has_account(sk))
 		return;
 	if (sk->sk_forward_alloc >= SK_MEM_QUANTUM)
-		__sk_mem_reclaim(sk);
+		__sk_mem_reclaim(sk, sk->sk_forward_alloc);
 }
 
 static inline void sk_mem_reclaim_partial(struct sock *sk)
@@ -1417,7 +1417,7 @@
 	if (!sk_has_account(sk))
 		return;
 	if (sk->sk_forward_alloc > SK_MEM_QUANTUM)
-		__sk_mem_reclaim(sk);
+		__sk_mem_reclaim(sk, sk->sk_forward_alloc - 1);
 }
 
 static inline void sk_mem_charge(struct sock *sk, int size)