From: Johannes Weiner <hannes@xxxxxxxxxxx>
Subject: mm: khugepaged: fix radix tree node leak in shmem collapse error path
The radix tree counts valid entries in each tree node. Entries stored in
the tree cannot be removed by simpling storing NULL in the slot or the
internal counters will be off and the node never gets freed again.
When collapsing a shmem page fails, restore the holes that were filled
with radix_tree_insert() with a proper radix tree deletion.
Fixes: f3f0e1d2150b ("khugepaged: add support of collapse for tmpfs/shmem pages")
Link: http://lkml.kernel.org/r/20161117191138.22769-3-hannes@xxxxxxxxxxx
Signed-off-by: Johannes Weiner <hannes@xxxxxxxxxxx>
Reported-by: Jan Kara <jack@xxxxxxx>
Acked-by: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx>
Reviewed-by: Jan Kara <jack@xxxxxxx>
Cc: Hugh Dickins <hughd@xxxxxxxxxx>
Cc: Matthew Wilcox <mawilcox@xxxxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/khugepaged.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)
diff -puN mm/khugepaged.c~mm-khugepaged-fix-radix-tree-node-leak-in-shmem-collapse-error-path mm/khugepaged.c
--- a/mm/khugepaged.c~mm-khugepaged-fix-radix-tree-node-leak-in-shmem-collapse-error-path
+++ a/mm/khugepaged.c
@@ -1525,9 +1525,11 @@ tree_unlocked:
if (!page || iter.index < page->index) {
if (!nr_none)
break;
- /* Put holes back where they were */
- radix_tree_replace_slot(slot, NULL);
nr_none--;
+ /* Put holes back where they were */
+ radix_tree_delete(&mapping->page_tree,
+ iter.index);
+ slot = radix_tree_iter_next(&iter);
continue;
}
_
--
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