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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: 6ad3122a08 ("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>
This commit is contained in:
Miroslav Urbanek 2016-11-21 15:48:21 +01:00 committed by Steffen Klassert
parent 330e832abd
commit 6b22648781
1 changed files with 2 additions and 4 deletions
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6
net/core/flow.c
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@ -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;
}