This is a note to let you know that I've just added the patch titled
net: tcp_memcontrol: properly detect ancestor socket pressure
to the 4.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
net-tcp_memcontrol-properly-detect-ancestor-socket-pressure.patch
and it can be found in the queue-4.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 8c2c2358b236530bc2c79b4c2a447cbdbc3d96d7 Mon Sep 17 00:00:00 2001
From: Johannes Weiner <hannes@xxxxxxxxxxx>
Date: Thu, 14 Jan 2016 15:20:59 -0800
Subject: net: tcp_memcontrol: properly detect ancestor socket pressure
From: Johannes Weiner <hannes@xxxxxxxxxxx>
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@xxxxxxxxxxx>
Acked-by: David S. Miller <davem@xxxxxxxxxxxxx>
Reviewed-by: Vladimir Davydov <vdavydov@xxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
include/net/sock.h | 10 ++++++----
1 file changed, 6 insertions(+), 4 deletions(-)
--- a/include/net/sock.h
+++ b/include/net/sock.h
@@ -1204,11 +1204,13 @@ static inline void memcg_memory_allocate
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,
Patches currently in stable-queue which might be from hannes@xxxxxxxxxxx are
queue-4.4/net-tcp_memcontrol-properly-detect-ancestor-socket-pressure.patch
