Mike Rapoport contacted me off-list with a regression in running criu. Periodic tests fail with an RCU stall during execution. Although rare, it is possible to hit this with other uses so this patch should be backported to fix the regression.
This patch set adds the fix and a test case to the maple tree test suite.
Link: https://lore.kernel.org/linux-mm/20221216185233.2036415-1-Liam.Howlett@oracl...
V1 changes: - Add stable to CC list - Add tested-by to Mike's Reported-by. - Moved test case to its own commit since the test code was added after the fixed-by commit and isn't part of the fix.
Liam R. Howlett (2): maple_tree: Fix mas_spanning_rebalance() on insufficient data test_maple_tree: Add test for mas_spanning_rebalance() on insufficient data
lib/maple_tree.c | 4 +++- lib/test_maple_tree.c | 23 +++++++++++++++++++++++ 2 files changed, 26 insertions(+), 1 deletion(-)
Mike Rapoport contacted me off-list with a regression in running criu. Periodic tests fail with an RCU stall during execution. Although rare, it is possible to hit this with other uses so this patch should be backported to fix the regression.
An insufficient node was causing an out-of-bounds access on the node in mas_leaf_max_gap(). The cause was the faulty detection of the new node being a root node when overwriting many entries at the end of the tree.
Fix the detection of a new root and ensure there is sufficient data prior to entering the spanning rebalance loop.
Cc: Andrei Vagin avagin@gmail.com Cc: usama.anjum@collabora.com CC: stable@vger.kernel.org Reported-and-tested-by: Mike Rapoport rppt@kernel.org Fixes: 54a611b60590 ("Maple Tree: add new data structure") Signed-off-by: Liam R. Howlett Liam.Howlett@oracle.com --- lib/maple_tree.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/lib/maple_tree.c b/lib/maple_tree.c index fe3947b80069..26e2045d3cda 100644 --- a/lib/maple_tree.c +++ b/lib/maple_tree.c @@ -2994,7 +2994,9 @@ static int mas_spanning_rebalance(struct ma_state *mas, mast->free = &free; mast->destroy = &destroy; l_mas.node = r_mas.node = m_mas.node = MAS_NONE; - if (!(mast->orig_l->min && mast->orig_r->max == ULONG_MAX) && + + /* Check if this is not root and has sufficient data. */ + if (((mast->orig_l->min != 0) || (mast->orig_r->max != ULONG_MAX)) && unlikely(mast->bn->b_end <= mt_min_slots[mast->bn->type])) mast_spanning_rebalance(mast);
Add a test to the maple tree test suite for the spanning rebalance insufficient node issue does not go undetected again.
Cc: Andrei Vagin avagin@gmail.com Cc: usama.anjum@collabora.com CC: stable@vger.kernel.org Cc: Mike Rapoport rppt@kernel.org Signed-off-by: Liam R. Howlett Liam.Howlett@oracle.com --- lib/test_maple_tree.c | 23 +++++++++++++++++++++++ 1 file changed, 23 insertions(+)
diff --git a/lib/test_maple_tree.c b/lib/test_maple_tree.c index f425f169ef08..497fc93ccf9e 100644 --- a/lib/test_maple_tree.c +++ b/lib/test_maple_tree.c @@ -2498,6 +2498,25 @@ static noinline void check_dup(struct maple_tree *mt) } }
+static noinline void check_bnode_min_spanning(struct maple_tree *mt) +{ + int i = 50; + MA_STATE(mas, mt, 0, 0); + + mt_set_non_kernel(9999); + mas_lock(&mas); + do { + mas_set_range(&mas, i*10, i*10+9); + mas_store(&mas, check_bnode_min_spanning); + } while (i--); + + mas_set_range(&mas, 240, 509); + mas_store(&mas, NULL); + mas_unlock(&mas); + mas_destroy(&mas); + mt_set_non_kernel(0); +} + static DEFINE_MTREE(tree); static int maple_tree_seed(void) { @@ -2742,6 +2761,10 @@ static int maple_tree_seed(void) check_dup(&tree); mtree_destroy(&tree);
+ mt_init_flags(&tree, MT_FLAGS_ALLOC_RANGE); + check_bnode_min_spanning(&tree); + mtree_destroy(&tree); + #if defined(BENCH) skip: #endif
linux-stable-mirror@lists.linaro.org
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Liam Howlett