[PATCH v4 2/4] sock: Always take memcg pressure into consideration

[Abel Wu]

The sk_under_memory_pressure() is called to check whether there is
memory pressure related to this socket. But now it ignores the net-
memcg's pressure if the proto of the socket doesn't care about the
global pressure, which may put burden on its memcg compaction or
reclaim path (also remember that socket memory is un-reclaimable).

So always check the memcg's vm status to alleviate memstalls when
it's in pressure.

Signed-off-by: Abel Wu <wuyun.abel@xxxxxxxxxxxxx>
---
 include/net/sock.h | 6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)

diff --git a/include/net/sock.h b/include/net/sock.h
index 641c9373b44b..b0e5533e5909 100644
--- a/include/net/sock.h
+++ b/include/net/sock.h
@@ -1411,13 +1411,11 @@ static inline bool sk_has_memory_pressure(const struct sock *sk)
 
 static inline bool sk_under_memory_pressure(const struct sock *sk)
 {
-	if (!sk->sk_prot->memory_pressure)
-		return false;
-
 	if (mem_cgroup_under_socket_pressure(sk->sk_memcg))
 		return true;
 
-	return !!*sk->sk_prot->memory_pressure;
+	return sk->sk_prot->memory_pressure &&
+		*sk->sk_prot->memory_pressure;
 }
 
 static inline long
-- 
2.37.3