Re: [PATCH v2 1/4] lib/rhashtable: simplify bucket_table_alloc()

From: Michal Hocko
Date: Mon Jun 25 2018 - 05:13:23 EST


On Fri 22-06-18 11:15:40, Davidlohr Bueso wrote:
> As of ce91f6ee5b3 (mm: kvmalloc does not fallback to vmalloc for incompatible gfp flag),
> we can simplify the caller and trust kvzalloc() to just do the right thing. For the
> case of the GFP_ATOMIC context, we can drop the __GFP_NORETRY flag for obvious reasons,
> and for the __GFP_NOWARN case, however, it is changed such that the caller passes the
> flag instead of making bucket_table_alloc() handle it.
>
> This slightly changes the gfp flags passed on to nested_table_alloc() as it will now
> also use GFP_ATOMIC | __GFP_NOWARN. However, I consider this a positive consequence
> as for the same reasons we want nowarn semantics in bucket_table_alloc().
>
> Signed-off-by: Davidlohr Bueso <dbueso@xxxxxxx>

Acked-by: Michal Hocko <mhocko@xxxxxxxx>

> ---
>
> v2:
> - Changes based on Neil's concerns about keeping nowarn flag.
> - Better changelog.
>
>
> lib/rhashtable.c | 7 ++-----
> 1 file changed, 2 insertions(+), 5 deletions(-)
>
> diff --git a/lib/rhashtable.c b/lib/rhashtable.c
> index 9427b5766134..083f871491a1 100644
> --- a/lib/rhashtable.c
> +++ b/lib/rhashtable.c
> @@ -175,10 +175,7 @@ static struct bucket_table *bucket_table_alloc(struct rhashtable *ht,
> int i;
>
> size = sizeof(*tbl) + nbuckets * sizeof(tbl->buckets[0]);
> - if (gfp != GFP_KERNEL)
> - tbl = kzalloc(size, gfp | __GFP_NOWARN | __GFP_NORETRY);
> - else
> - tbl = kvzalloc(size, gfp);
> + tbl = kvzalloc(size, gfp);
>
> size = nbuckets;
>
> @@ -459,7 +456,7 @@ static int rhashtable_insert_rehash(struct rhashtable *ht,
>
> err = -ENOMEM;
>
> - new_tbl = bucket_table_alloc(ht, size, GFP_ATOMIC);
> + new_tbl = bucket_table_alloc(ht, size, GFP_ATOMIC | __GFP_NOWARN);
> if (new_tbl == NULL)
> goto fail;
>
> --
> 2.16.4

--
Michal Hocko
SUSE Labs