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