netdev - Re: [BUG] Erroneous behavior in try_to

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Message-ID: <1446062699.7476.77.camel@edumazet-glaptop2.roam.corp.google.com>
Date:	Wed, 28 Oct 2015 13:04:59 -0700
From:	Eric Dumazet <eric.dumazet@...il.com>
To:	Nikolay Borisov <kernel@...p.com>
Cc:	alexander.h.duyck@...hat.com, David Miller <davem@...emloft.net>,
	netdev@...r.kernel.org,
	SiteGround Operations <operations@...eground.com>
Subject: Re: [BUG] Erroneous behavior in try_to_coalesce

On Thu, 2015-10-29 at 04:19 +0900, Nikolay Borisov wrote:

> 
> 
> Could you please comment whether it looks viable so that I can resend
> as a proper fix? Also the interesting question is what kind of packets
> could trigger this warn_on_once? In both traces ovs_packet_cmd_execute
> is present so I suspect it might be possible that somehow openvswitch is
> injecting wrong packets which make the kernel crash.

Bug is the packet producer, not in try_to_coalesce()

This issue comes up on netdev from times to times...

The WARN_ON() in try_to_coalesce() is an attempt to detect a producer
made a lie about truesize, leading to OOM in case of abuses.

Do not paper over the bug, find the root cause and fix it, thanks.



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