2023-09-15 17:20:39

by Jaeseon Sim

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

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 <[email protected]>
---
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

2023-09-18 21:50:45

by Liam R. Howlett

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

Sorry for the late reply.

* Jaeseon Sim <[email protected]> [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 <[email protected]>

Reviewed-by: Liam R. Howlett <[email protected]>

> ---
> 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