Patch "flowcache: Increase threshold for refusing new allocations" has been added to the 4.8-stable tree

Patch "flowcache: Increase threshold for refusing new allocations" has been added to the 4.8-stable tree

[gregkh]

This is a note to let you know that I've just added the patch titled

    flowcache: Increase threshold for refusing new allocations

to the 4.8-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:
     flowcache-increase-threshold-for-refusing-new-allocations.patch
and it can be found in the queue-4.8 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From 6b226487815574193c1da864f2eac274781a2b0c Mon Sep 17 00:00:00 2001
From: Miroslav Urbanek <mu@miroslavurbanek.com>
Date: Mon, 21 Nov 2016 15:48:21 +0100
Subject: flowcache: Increase threshold for refusing new allocations
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

From: Miroslav Urbanek <mu@miroslavurbanek.com>

commit 6b226487815574193c1da864f2eac274781a2b0c upstream.

The threshold for OOM protection is too small for systems with large
number of CPUs. Applications report ENOBUFs on connect() every 10
minutes.

The problem is that the variable net->xfrm.flow_cache_gc_count is a
global counter while the variable fc->high_watermark is a per-CPU
constant. Take the number of CPUs into account as well.

Fixes: 6ad3122a08e3 ("flowcache: Avoid OOM condition under preasure")
Reported-by: Lukáš Koldrt <lk@excello.cz>
Tested-by: Jan Hejl <jh@excello.cz>
Signed-off-by: Miroslav Urbanek <mu@miroslavurbanek.com>
Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 net/core/flow.c |    6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)

--- a/net/core/flow.c
+++ b/net/core/flow.c
@@ -95,7 +95,6 @@ static void flow_cache_gc_task(struct wo
 	list_for_each_entry_safe(fce, n, &gc_list, u.gc_list) {
 		flow_entry_kill(fce, xfrm);
 		atomic_dec(&xfrm->flow_cache_gc_count);
-		WARN_ON(atomic_read(&xfrm->flow_cache_gc_count) < 0);
 	}
 }
 
@@ -236,9 +235,8 @@ flow_cache_lookup(struct net *net, const
 		if (fcp->hash_count > fc->high_watermark)
 			flow_cache_shrink(fc, fcp);
 
-		if (fcp->hash_count > 2 * fc->high_watermark ||
-		    atomic_read(&net->xfrm.flow_cache_gc_count) > fc->high_watermark) {
-			atomic_inc(&net->xfrm.flow_cache_genid);
+		if (atomic_read(&net->xfrm.flow_cache_gc_count) >
+		    2 * num_online_cpus() * fc->high_watermark) {
 			flo = ERR_PTR(-ENOBUFS);
 			goto ret_object;
 		}


Patches currently in stable-queue which might be from mu@miroslavurbanek.com are

queue-4.8/flowcache-increase-threshold-for-refusing-new-allocations.patch