linux-kernel - [PATCH 03/13] net: tcp_memcontrol: remove bogus hierarchy pressure propagation

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <1448401925-22501-4-git-send-email-hannes@cmpxchg.org>
Date:	Tue, 24 Nov 2015 16:51:55 -0500
From:	Johannes Weiner <hannes@...xchg.org>
To:	Andrew Morton <akpm@...ux-foundation.org>
Cc:	David Miller <davem@...emloft.net>,
	Vladimir Davydov <vdavydov@...tuozzo.com>,
	Michal Hocko <mhocko@...e.cz>, Tejun Heo <tj@...nel.org>,
	Eric Dumazet <eric.dumazet@...il.com>, netdev@...r.kernel.org,
	linux-mm@...ck.org, cgroups@...r.kernel.org,
	linux-kernel@...r.kernel.org, kernel-team@...com
Subject: [PATCH 03/13] net: tcp_memcontrol: remove bogus hierarchy pressure propagation

When a cgroup currently breaches its socket memory limit, it enters
memory pressure mode for itself and its *ancestors*. This throttles
transmission in unrelated sibling and cousin subtrees that have
nothing to do with the breached limit.

On the contrary, breaching a limit should make that group and its
*children* enter memory pressure mode. But this happens already,
albeit lazily: if an ancestor limit is breached, siblings will enter
memory pressure on their own once the next packet arrives for them.

So no additional hierarchy code is needed. Remove the bogus stuff.

Signed-off-by: Johannes Weiner <hannes@...xchg.org>
Acked-by: David S. Miller <davem@...emloft.net>
Reviewed-by: Vladimir Davydov <vdavydov@...tuozzo.com>
---
 include/net/sock.h | 19 ++++---------------
 1 file changed, 4 insertions(+), 15 deletions(-)

diff --git a/include/net/sock.h b/include/net/sock.h
index 8133c71..e27a8bb 100644
--- a/include/net/sock.h
+++ b/include/net/sock.h
@@ -1152,14 +1152,8 @@ static inline void sk_leave_memory_pressure(struct sock *sk)
 	if (*memory_pressure)
 		*memory_pressure = 0;
 
-	if (mem_cgroup_sockets_enabled && sk->sk_cgrp) {
-		struct cg_proto *cg_proto = sk->sk_cgrp;
-		struct proto *prot = sk->sk_prot;
-
-		for (; cg_proto; cg_proto = parent_cg_proto(prot, cg_proto))
-			cg_proto->memory_pressure = 0;
-	}
-
+	if (mem_cgroup_sockets_enabled && sk->sk_cgrp)
+		sk->sk_cgrp->memory_pressure = 0;
 }
 
 static inline void sk_enter_memory_pressure(struct sock *sk)
@@ -1167,13 +1161,8 @@ static inline void sk_enter_memory_pressure(struct sock *sk)
 	if (!sk->sk_prot->enter_memory_pressure)
 		return;
 
-	if (mem_cgroup_sockets_enabled && sk->sk_cgrp) {
-		struct cg_proto *cg_proto = sk->sk_cgrp;
-		struct proto *prot = sk->sk_prot;
-
-		for (; cg_proto; cg_proto = parent_cg_proto(prot, cg_proto))
-			cg_proto->memory_pressure = 1;
-	}
+	if (mem_cgroup_sockets_enabled && sk->sk_cgrp)
+		sk->sk_cgrp->memory_pressure = 1;
 
 	sk->sk_prot->enter_memory_pressure(sk);
 }
-- 
2.6.2

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/