The patch titled
Subject: maple_tree: add mas_is_active() to detect in-tree walks
has been added to the -mm mm-hotfixes-unstable branch. Its filename is
maple_tree-add-mas_active-to-detect-in-tree-walks.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/maple_tree-add-mas_active-to-detect-in-tree-walks.patch
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 R. Howlett" <Liam.Howlett@xxxxxxxxxx>
Subject: maple_tree: add mas_is_active() to detect in-tree walks
Date: Thu, 21 Sep 2023 14:12:35 -0400
Patch series "maple_tree: Fix mas_prev() state regression".
Pedro Falcato contacted me on IRC with an mprotect regression which was
bisected back to the iterator changes for maple tree. Root cause analysis
showed the mas_prev() running off the end of the VMA space (previous from
0) followed by mas_find(), would skip the first value.
This patchset introduces maple state underflow/overflow so the sequence of
calls on the maple state will return what the user expects.
This patch (of 2):
Instead of constantly checking each possibility of the maple state,
create a fast path that will skip over checking unlikely states.
Link: https://lkml.kernel.org/r/20230921181236.509072-1-Liam.Howlett@xxxxxxxxxx
Link: https://lkml.kernel.org/r/20230921181236.509072-2-Liam.Howlett@xxxxxxxxxx
Signed-off-by: Liam R. Howlett <Liam.Howlett@xxxxxxxxxx>
Cc: Pedro Falcato <pedro.falcato@xxxxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
include/linux/maple_tree.h | 9 +++++++++
1 file changed, 9 insertions(+)
--- a/include/linux/maple_tree.h~maple_tree-add-mas_active-to-detect-in-tree-walks
+++ a/include/linux/maple_tree.h
@@ -511,6 +511,15 @@ static inline bool mas_is_paused(const s
return mas->node == MAS_PAUSE;
}
+/* Check if the mas is pointing to a node or not */
+static inline bool mas_is_active(struct ma_state *mas)
+{
+ if ((unsigned long)mas->node >= MAPLE_RESERVED_RANGE)
+ return true;
+
+ return false;
+}
+
/**
* mas_reset() - Reset a Maple Tree operation state.
* @mas: Maple Tree operation state.
_
Patches currently in -mm which might be from Liam.Howlett@xxxxxxxxxx are
maple_tree-add-mas_active-to-detect-in-tree-walks.patch
maple_tree-add-mas_underflow-and-mas_overflow-states.patch
