netdev - Re: [PATCH v2] netfilter: ipset: Fix sleeping memory allocation in atomic context

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Date:	Thu, 15 Oct 2015 23:20:04 +0300
From:	Nikolay Borisov <n.borisov@...eground.com>
To:	Eric Dumazet <eric.dumazet@...il.com>
Cc:	Jozsef Kadlecsik <kadlec@...ckhole.kfki.hu>,
	Nikolay Borisov <kernel@...p.com>,
	Pablo Neira Ayuso <pablo@...filter.org>,
	David Miller <davem@...emloft.net>,
	netfilter-devel@...r.kernel.org, netdev@...r.kernel.org,
	SiteGround Operations <operations@...eground.com>
Subject: Re: [PATCH v2] netfilter: ipset: Fix sleeping memory allocation in
 atomic context

On Thu, Oct 15, 2015 at 9:46 PM, Eric Dumazet <eric.dumazet@...il.com> wrote:
> On Thu, 2015-10-15 at 20:25 +0200, Jozsef Kadlecsik wrote:
>
>> Nikolay answered this pretty well: we wouldn't need the spinlock at all,
>> because all commands are serialized anyway with the netlink mutex. But the
>> garbage collector is called by a timer and therefore spinlock is used.
>>
>
> Good, please Nikolay, send a v2 of the patch with all these details
> explained in the changelog, so that we can all agree.

While GFP_ATOMIC does indeed look the correct solution for this particular
case I was wondering whether something like (GFP_KERNEL & ~__GFP_WAIT)
wouldn't also make the cut without causing sleeping? I guess this is exactly
the sort of situation that Mel Gorman's patch can address
(marc.info/?l=linux-kernel&m=144283282101953) ?

In any case I will send v2 tomorrow.

>
> If properly explained, no need to add the stack trace which does not
> really tell us the story.
>
> Thanks !
>
>
>
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