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[3.19.y-ckt,stable] Patch "net: tcp_memcontrol: properly detect ancestor socket pressure" has been added to the 3.19.y-ckt tree

Message ID 1454029864-15419-1-git-send-email-kamal@canonical.com
State New
Headers show

Commit Message

Kamal Mostafa Jan. 29, 2016, 1:11 a.m. UTC 
This is a note to let you know that I have just added a patch titled

    net: tcp_memcontrol: properly detect ancestor socket pressure

to the linux-3.19.y-queue branch of the 3.19.y-ckt extended stable tree 
which can be found at:

    http://kernel.ubuntu.com/git/ubuntu/linux.git/log/?h=linux-3.19.y-queue

This patch is scheduled to be released in version 3.19.8-ckt14.

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.19.y-ckt tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Kamal

---8<------------------------------------------------------------

From 9c5b19970d2fee9d64b342777bdf6b6d62ad4a67 Mon Sep 17 00:00:00 2001
From: Johannes Weiner <hannes@cmpxchg.org>
Date: Thu, 14 Jan 2016 15:20:59 -0800
Subject: net: tcp_memcontrol: properly detect ancestor socket pressure

commit 8c2c2358b236530bc2c79b4c2a447cbdbc3d96d7 upstream.

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.

Fixes: 3e32cb2e0a12 ("mm: memcontrol: lockless page counters")
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: David S. Miller <davem@davemloft.net>
Reviewed-by: Vladimir Davydov <vdavydov@virtuozzo.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>
---
 include/net/sock.h | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

--
1.9.1
diff mbox

Patch

diff --git a/include/net/sock.h b/include/net/sock.h
index 7c22c16..a2ee838 100644
--- a/include/net/sock.h
+++ b/include/net/sock.h
@@ -1237,11 +1237,13 @@  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,