linux-kernel - [PATCH net-next v5 2/3] sock: Always take memcg pressure into consideration

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Message-Id: <20230602081135.75424-3-wuyun.abel@bytedance.com>
Date:   Fri,  2 Jun 2023 16:11:34 +0800
From:   Abel Wu <wuyun.abel@...edance.com>
To:     "David S . Miller" <davem@...emloft.net>,
        Eric Dumazet <edumazet@...gle.com>,
        Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>,
        Johannes Weiner <hannes@...xchg.org>,
        Michal Hocko <mhocko@...nel.org>,
        Vladimir Davydov <vdavydov.dev@...il.com>,
        Shakeel Butt <shakeelb@...gle.com>,
        Muchun Song <muchun.song@...ux.dev>
Cc:     Simon Horman <simon.horman@...igine.com>, netdev@...r.kernel.org,
        linux-mm@...ck.org, cgroups@...r.kernel.org,
        linux-kernel@...r.kernel.org, Abel Wu <wuyun.abel@...edance.com>
Subject: [PATCH net-next v5 2/3] sock: Always take memcg pressure into consideration

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@...edance.com>
---
 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 3f63253ee092..ad1895ffbc4a 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