netdev - Re: [PATCH v2 net 0/5] net: fix races accessing page->

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Date:	Fri, 10 Oct 2014 15:37:59 -0400 (EDT)
From:	David Miller <davem@...emloft.net>
To:	edumazet@...gle.com
Cc:	netdev@...r.kernel.org, alexander.h.duyck@...hat.com,
	jeffrey.t.kirsher@...el.com, andreslc@...gle.com,
	gthelen@...gle.com, hughd@...gle.com, rientjes@...gle.com
Subject: Re: [PATCH v2 net 0/5] net: fix races accessing page->_count

From: Eric Dumazet <edumazet@...gle.com>
Date: Fri, 10 Oct 2014 04:48:13 -0700

> This is illegal to use atomic_set(&page->_count, ...) even if we 'own'
> the page. Other entities in the kernel need to use get_page_unless_zero()
> to get a reference to the page before testing page properties, so we could
> loose a refcount increment.
> 
> The only case it is valid is when page->_count is 0, we can use this in
> __netdev_alloc_frag()
> 
> Note that I never seen crashes caused by these races, the issue was reported
> by Andres Lagar-Cavilla and Hugh Dickins.

Series applied, thanks Eric.
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