Commit 6b226487 authored Nov 21, 2016 by Miroslav Urbanek Committed by Steffen Klassert Nov 23, 2016

flowcache: Increase threshold for refusing new allocations



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: 6ad3122a ("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>

parent 330e832a

net/core/flow.c

+2 −4

Original line number	Diff line number	Diff line
		@@ -95,7 +95,6 @@ static void flow_cache_gc_task(struct work_struct *work)
		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 struct flowi key, u16 family, u8 dir,
		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;
		}

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