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Date:	Fri, 10 Oct 2014 04:48:13 -0700
From:	Eric Dumazet <edumazet@...gle.com>
To:	"David S. Miller" <davem@...emloft.net>
Cc:	netdev@...r.kernel.org,
	Alexander Duyck <alexander.h.duyck@...hat.com>,
	Jeff Kirsher <jeffrey.t.kirsher@...el.com>,
	Andres Lagar-Cavilla <andreslc@...gle.com>,
	Greg Thelen <gthelen@...gle.com>,
	Hugh Dickins <hughd@...gle.com>,
	David Rientjes <rientjes@...gle.com>,
	Eric Dumazet <edumazet@...gle.com>
Subject: [PATCH v2 net 0/5] net: fix races accessing page->_count

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.


Eric Dumazet (5):
  fm10k: fix race accessing page->_count
  igb: fix race accessing page->_count
  ixgbe: fix race accessing page->_count
  mlx4: fix race accessing page->_count
  net: fix races in page->_count manipulation

 drivers/net/ethernet/intel/fm10k/fm10k_main.c |  7 +++----
 drivers/net/ethernet/intel/igb/igb_main.c     |  7 +++----
 drivers/net/ethernet/intel/ixgbe/ixgbe_main.c |  8 +++-----
 drivers/net/ethernet/mellanox/mlx4/en_rx.c    |  6 +++---
 net/core/skbuff.c                             | 25 ++++++++++++++++++-------
 5 files changed, 30 insertions(+), 23 deletions(-)

-- 
2.1.0.rc2.206.gedb03e5

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