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

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Message-ID: <45afb63e-bd0c-83a7-4f52-7890750dffd0@cogentembedded.com>
Date:   Tue, 24 Jul 2018 12:58:19 +0300
From:   Sergei Shtylyov <sergei.shtylyov@...entembedded.com>
To:     Li RongQing <lirongqing@...du.com>, 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

Hello!

On 7/24/2018 10:19 AM, Li RongQing 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:
> 
> 	delay_tsc
> 	__delay
> 	_raw_spin_lock
> 	_spin_lock
> 	mmu_shrink
> 	shrink_slab
> 	zone_reclaim
> 	get_page_from_freelist
> 	__alloc_pages_nodemask
> 	alloc_pages_current
> 	__get_free_pages
> 	nf_ct_alloc_hashtable
> 	nf_conntrack_init_net
> 	setup_net
> 	copy_net_ns
> 	create_new_namespaces
> 	copy_namespaces
> 	copy_process
> 	do_fork
> 	sys_clone
> 	stub_clone
> 	__clone
> 
> not use the directly memory reclaim flag to avoid stall

    You mean "do not use"?

> Signed-off-by: Ni Xun <nixun@...du.com>
> Signed-off-by: Zhang Yu <zhangyu31@...du.com>
> Signed-off-by: Wang Li <wangli39@...du.com>
> Signed-off-by: Li RongQing <lirongqing@...du.com>
[...]

MBR, Sergei