linux-kernel - [PATCH v4 4/4] sock: Remove redundant cond of memcg pressure

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Message-Id: <20230530114011.13368-5-wuyun.abel@bytedance.com>
Date:   Tue, 30 May 2023 19:40:11 +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 v4 4/4] sock: Remove redundant cond of memcg pressure

Now with the previous patch, __sk_mem_raise_allocated() considers
the memory pressure of both global and the socket's memcg on a func-
wide level, making the condition of memcg's pressure in question
redundant.

Signed-off-by: Abel Wu <wuyun.abel@...edance.com>
---
 net/core/sock.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/net/core/sock.c b/net/core/sock.c
index 801df091e37a..86735ad2f903 100644
--- a/net/core/sock.c
+++ b/net/core/sock.c
@@ -3020,9 +3020,15 @@ int __sk_mem_raise_allocated(struct sock *sk, int size, int amt, int kind)
 	if (sk_has_memory_pressure(sk)) {
 		u64 alloc;
 
-		if (!sk_under_memory_pressure(sk))
+		if (!sk_under_global_memory_pressure(sk))
 			return 1;
+
 		alloc = sk_sockets_allocated_read_positive(sk);
+
+		/* If under global pressure, allow the sockets that are below
+		 * average memory usage to raise, trying to be fair among all
+		 * the sockets under global constrains.
+		 */
 		if (sk_prot_mem_limits(sk, 2) > alloc *
 		    sk_mem_pages(sk->sk_wmem_queued +
 				 atomic_read(&sk->sk_rmem_alloc) +
-- 
2.37.3