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authorMatthew Wilcox <willy@linux.intel.com>2016-02-02 16:57:52 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2016-02-03 08:28:43 -0800
commit46437f9a554fbe3e110580ca08ab703b59f2f95a (patch)
tree826c5a8180792c3c68f57686d41bf69f01b2985d /drivers
parent3c1da7beeee02560cd0f0c66c5a59fce3c6746e3 (diff)
downloadlinux-46437f9a554fbe3e110580ca08ab703b59f2f95a.tar.bz2
radix-tree: fix race in gang lookup
If the indirect_ptr bit is set on a slot, that indicates we need to redo the lookup. Introduce a new function radix_tree_iter_retry() which forces the loop to retry the lookup by setting 'slot' to NULL and turning the iterator back to point at the problematic entry. This is a pretty rare problem to hit at the moment; the lookup has to race with a grow of the radix tree from a height of 0. The consequences of hitting this race are that gang lookup could return a pointer to a radix_tree_node instead of a pointer to whatever the user had inserted in the tree. Fixes: cebbd29e1c2f ("radix-tree: rewrite gang lookup using iterator") Signed-off-by: Matthew Wilcox <willy@linux.intel.com> Cc: Hugh Dickins <hughd@google.com> Cc: Ohad Ben-Cohen <ohad@wizery.com> Cc: Konstantin Khlebnikov <khlebnikov@openvz.org> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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