On Thu 17-11-16 14:11:31, Johannes Weiner wrote:
> 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")
> Reported-by: Jan Kara <jack@xxxxxxx>
> Signed-off-by: Johannes Weiner <hannes@xxxxxxxxxxx>
Looks good. You can add:
Reviewed-by: Jan Kara <jack@xxxxxxx>
Honza
> ---
> mm/khugepaged.c | 6 ++++--
> 1 file changed, 4 insertions(+), 2 deletions(-)
>
> diff --git a/mm/khugepaged.c b/mm/khugepaged.c
> index bdfdab40a813..d553c294de40 100644
> --- a/mm/khugepaged.c
> +++ b/mm/khugepaged.c
> @@ -1523,9 +1523,11 @@ static void collapse_shmem(struct mm_struct *mm,
> 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;
> }
>
> --
> 2.10.2
>
--
Jan Kara <jack@xxxxxxxx>
SUSE Labs, CR
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