Merge branch 'net-drivers-pgcnt'
Eric Dumazet says:
====================
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.
====================
Signed-off-by: David S. Miller <davem@davemloft.net>
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