linux-kernel - [PATCH 03/14] net: tcp_memcontrol: properly detect ancestor socket pressure

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: <1447371693-25143-4-git-send-email-hannes@cmpxchg.org>
Date:	Thu, 12 Nov 2015 18:41:22 -0500
From:	Johannes Weiner <hannes@...xchg.org>
To:	David Miller <davem@...emloft.net>,
	Andrew Morton <akpm@...ux-foundation.org>
Cc:	Vladimir Davydov <vdavydov@...tuozzo.com>,
	Tejun Heo <tj@...nel.org>, Michal Hocko <mhocko@...e.cz>,
	netdev@...r.kernel.org, linux-mm@...ck.org,
	cgroups@...r.kernel.org, linux-kernel@...r.kernel.org,
	kernel-team@...com
Subject: [PATCH 03/14] net: tcp_memcontrol: properly detect ancestor socket pressure

When charging socket memory, the code currently checks only the local
page counter for excess to determine whether the memcg is under socket
pressure. But even if the local counter is fine, one of the ancestors
could have breached its limit, which should also force this child to
enter socket pressure. This currently doesn't happen.

Fix this by using page_counter_try_charge() first. If that fails, it
means that either the local counter or one of the ancestors are in
excess of their limit, and the child should enter socket pressure.

Signed-off-by: Johannes Weiner <hannes@...xchg.org>
---
 include/net/sock.h | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/include/net/sock.h b/include/net/sock.h
index bbf7c2c..c4b33c9 100644
--- a/include/net/sock.h
+++ b/include/net/sock.h
@@ -1190,11 +1190,13 @@ static inline void memcg_memory_allocated_add(struct cg_proto *prot,
 					      unsigned long amt,
 					      int *parent_status)
 {
-	page_counter_charge(&prot->memory_allocated, amt);
+	struct page_counter *counter;
+
+	if (page_counter_try_charge(&prot->memory_allocated, amt, &counter))
+		return;
 
-	if (page_counter_read(&prot->memory_allocated) >
-	    prot->memory_allocated.limit)
-		*parent_status = OVER_LIMIT;
+	page_counter_charge(&prot->memory_allocated, amt);
+	*parent_status = OVER_LIMIT;
 }
 
 static inline void memcg_memory_allocated_sub(struct cg_proto *prot,
-- 
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/