The patch titled Subject: maple_tree: fix mas_spanning_rebalance() on insufficient data has been added to the -mm mm-hotfixes-unstable branch. Its filename is maple_tree-fix-mas_spanning_rebalance-on-insufficient-data.patch
This patch will shortly appear at https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches...
This patch will later appear in the mm-hotfixes-unstable branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
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------------------------------------------------------ From: Liam Howlett liam.howlett@oracle.com Subject: maple_tree: fix mas_spanning_rebalance() on insufficient data Date: Mon, 19 Dec 2022 16:20:15 +0000
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 patchset adds the fix and a test case to the maple tree test suite.
This patch (of 2):
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.
Link: https://lkml.kernel.org/r/20221219161922.2708732-1-Liam.Howlett@oracle.com Link: https://lkml.kernel.org/r/20221219161922.2708732-2-Liam.Howlett@oracle.com Fixes: 54a611b60590 ("Maple Tree: add new data structure") Signed-off-by: Liam R. Howlett Liam.Howlett@oracle.com Reported-by: Mike Rapoport rppt@kernel.org Tested-by: Mike Rapoport rppt@kernel.org Cc: Andrei Vagin avagin@gmail.com Cc: Mike Rapoport rppt@kernel.org Cc: Muhammad Usama Anjum usama.anjum@collabora.com Cc: stable@vger.kernel.org Signed-off-by: Andrew Morton akpm@linux-foundation.org ---
lib/maple_tree.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-)
--- a/lib/maple_tree.c~maple_tree-fix-mas_spanning_rebalance-on-insufficient-data +++ a/lib/maple_tree.c @@ -2994,7 +2994,9 @@ static int mas_spanning_rebalance(struct 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);
_
Patches currently in -mm which might be from liam.howlett@oracle.com are
maple_tree-fix-mas_spanning_rebalance-on-insufficient-data.patch test_maple_tree-add-test-for-mas_spanning_rebalance-on-insufficient-data.patch