netdev - Re: [PATCH] netfilter: avoid stalls in nf_ct_alloc

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Date:   Tue, 24 Jul 2018 11:19:46 +0200
From:   Florian Westphal <fw@...len.de>
To:     Li RongQing <lirongqing@...du.com>
Cc:     netdev@...r.kernel.org, pablo@...filter.org,
        kadlec@...ckhole.kfki.hu, fw@...len.de
Subject: Re: [PATCH] netfilter: avoid stalls in nf_ct_alloc_hashtable

Li RongQing <lirongqing@...du.com> wrote:
> when system forks a process with CLONE_NEWNET flag under the
> high memory pressure, it will trigger memory reclaim and stall
> for a long time because nf_ct_alloc_hashtable need to allocate
> high-order memory at that time. The calltrace as below:

> 	nf_ct_alloc_hashtable
> 	nf_conntrack_init_net

This call trace is from a kernel < 4.7.

commit 56d52d4892d0e478a005b99ed10d0a7f488ea8c1
netfilter: conntrack: use a single hashtable for all namespaces

removed per-netns hash table.