Fix sock_exceed_buf_limit not being triggered in __sk_mem_raise_allocated

When a process under memory pressure is not part of any cgroup and
the charged flag is false, trace_sock_exceed_buf_limit was not called
as expected.

This regression was introduced by commit 2def8ff ("sock:
Code cleanup on __sk_mem_raise_allocated()"). The fix changes the
default value of charged to true while preserving existing logic.

Fixes: 2def8ff ("sock: Code cleanup on __sk_mem_raise_allocated()")
Signed-off-by: Abel Wu <wuyun.abel@bytedance.com>
Signed-off-by: Tengteng Yang <yangtengteng@bytedance.com>
Link: https://patch.msgid.link/20250527030419.67693-1-yangtengteng@bytedance.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

Author: Tengteng Yang

net/core/sock.c

@@ -3284,16 +3284,16 @@ int __sk_mem_raise_allocated(struct sock *sk, int size, int amt, int kind)
 {
 	struct mem_cgroup *memcg = mem_cgroup_sockets_enabled ? sk->sk_memcg : NULL;
 	struct proto *prot = sk->sk_prot;
-	bool charged = false;
+	bool charged = true;
 	long allocated;
 
 	sk_memory_allocated_add(sk, amt);
 	allocated = sk_memory_allocated(sk);
 
 	if (memcg) {
-		if (!mem_cgroup_charge_skmem(memcg, amt, gfp_memcg_charge()))
+		charged = mem_cgroup_charge_skmem(memcg, amt, gfp_memcg_charge());
+		if (!charged)
 			goto suppress_allocation;
-		charged = true;
 	}
 
 	/* Under limit. */
@@ -3378,7 +3378,7 @@ int __sk_mem_raise_allocated(struct sock *sk, int size, int amt, int kind)
 
 	sk_memory_allocated_sub(sk, amt);
 
-	if (charged)
+	if (memcg && charged)
 		mem_cgroup_uncharge_skmem(memcg, amt);
 
 	return 0;