[PATCH 0/5] fix radix tree multi-order iteration race

[Ross Zwisler]

The following series gets the radix tree test suite compiling again in
the current linux/master, adds a unit test which exposes a race in the
radix tree multi-order iteration code, and then fixes that race.

This race was initially hit on a v4.15 based kernel and results in a GP
fault.  I've described the race in detail in patches 4 and 5.

The fix is simple and necessary, and I think it should be merged for
v4.17.

This tree has gotten positive build confirmation from the 0-day bot,
passes the updated radix tree test suite, xfstests, and the original
test that was hitting the race with the v4.15 based kernel.

Ross Zwisler (5):
  radix tree test suite: fix mapshift build target
  radix tree test suite: fix compilation issue
  radix tree test suite: add item_delete_rcu()
  radix tree test suite: multi-order iteration race
  radix tree: fix multi-order iteration race

 lib/radix-tree.c                      |  6 ++--
 tools/include/linux/spinlock.h        |  3 +-
 tools/testing/radix-tree/Makefile     |  6 ++--
 tools/testing/radix-tree/multiorder.c | 63 +++++++++++++++++++++++++++++++++++
 tools/testing/radix-tree/test.c       | 19 +++++++++++
 tools/testing/radix-tree/test.h       |  3 ++
 6 files changed, 91 insertions(+), 9 deletions(-)

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2.14.3