On Fri, 16 Dec 2022 18:53:15 +0000 Liam Howlett <liam.howlett@xxxxxxxxxx> wrote:
> 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.
>
> Add a testcase to the maple tree test suite for this issue.
Shall do.
> Cc: Andrei Vagin <avagin@xxxxxxxxx>
> Cc: usama.anjum@xxxxxxxxxxxxx
> Reported-by: Mike Rapoport <rppt@xxxxxxxxxx>
> Fixes: 54a611b60590 ("Maple Tree: add new data structure")
> Signed-off-by: Liam R. Howlett <Liam.Howlett@xxxxxxxxxx>
I guess we want a cc:stable there?
> lib/test_maple_tree.c | 23 +++++++++++++++++++++++
Belated review: all this code runs at __init time, so every dang
function in there really should be marked __init, data marked
__initdata, etc. Like lib/test_bitmap.c.
I wonder if there's some trick we can do external to the .c file to
have the same effect.
Also, maple_tree_seed():set[] could be static ;). So we don't have to
initialize it at runtime. Better would be static const. Nitpick.
