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

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Message-ID: <1444942391.25595.11.camel@edumazet-glaptop2.roam.corp.google.com>
Date:	Thu, 15 Oct 2015 13:53:11 -0700
From:	Eric Dumazet <eric.dumazet@...il.com>
To:	Nikolay Borisov <n.borisov@...eground.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, 2015-10-15 at 23:20 +0300, Nikolay Borisov wrote:

> 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) ?

This is not applicable here, because the caller would have to find a way
to keep trying.

I believe one way to handle this problem (in a followup patch) would be
to use a work queue for the gc, not a timer.

Using a timer for gc is almost always subject to big problems anyway.

Thanks.



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