Re: [PATCH v2] maple_tree: use mas_node_count_gfp on mas_expected_entries

From: Liam R. Howlett
Date: Mon Sep 18 2023 - 14:06:45 EST


Sorry for the late reply.

* Jaeseon Sim <jason.sim@xxxxxxxxxxx> [230915 05:32]:
> Use mas_node_count_gfp with GFP_KERNEL instead of
> GFP_NOWAIT | __GFP_NOWARN on mas_expected_entries
> in order to allow memory reclaim.
>
> Currently, fork errors occur on low free memory as follows:
>
> Zygote : Failed to fork child process: Out of memory (12)
>
> -ENOMEM was returned as following path:
>
> mas_node_count
> mas_expected_entries
> dup_mmap
> dup_mm
> copy_mm
> copy_process
>
> Signed-off-by: Jaeseon Sim <jason.sim@xxxxxxxxxxx>

Reviewed-by: Liam R. Howlett <Liam.Howlett@xxxxxxxxxx>

> ---
> lib/maple_tree.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/lib/maple_tree.c b/lib/maple_tree.c
> index ee1ff0c59fd7..b0229271c24e 100644
> --- a/lib/maple_tree.c
> +++ b/lib/maple_tree.c
> @@ -5574,7 +5574,7 @@ int mas_expected_entries(struct ma_state *mas, unsigned long nr_entries)
> /* Internal nodes */
> nr_nodes += DIV_ROUND_UP(nr_nodes, nonleaf_cap);
> /* Add working room for split (2 nodes) + new parents */
> - mas_node_count(mas, nr_nodes + 3);
> + mas_node_count_gfp(mas, nr_nodes + 3, GFP_KERNEL);
>
> /* Detect if allocations run out */
> mas->mas_flags |= MA_STATE_PREALLOC;
> --
> 2.17.1