On Sat, Jun 17, 2023 at 03:09:55PM +0800, Miaohe Lin wrote:
> HASH_SMALL only works when parameter numentries is 0. But the sole caller
> futex_init() never calls alloc_large_system_hash() with numentries set to
> 0.
Doesn't it?
What happens when CONFIG_BASE_SMALL is set?
> So HASH_SMALL is obsolete and remove it.
> Signed-off-by: Miaohe Lin <linmiaohe@xxxxxxxxxx>
> ---
> include/linux/memblock.h | 2 --
> kernel/futex/core.c | 3 +--
> mm/mm_init.c | 10 +---------
> 3 files changed, 2 insertions(+), 13 deletions(-)
>
> diff --git a/include/linux/memblock.h b/include/linux/memblock.h
> index f71ff9f0ec81..346d80809517 100644
> --- a/include/linux/memblock.h
> +++ b/include/linux/memblock.h
> @@ -581,8 +581,6 @@ extern void *alloc_large_system_hash(const char *tablename,
> unsigned long high_limit);
>
> #define HASH_EARLY 0x00000001 /* Allocating during early boot? */
> -#define HASH_SMALL 0x00000002 /* sub-page allocation allowed, min
> - * shift passed via *_hash_shift */
> #define HASH_ZERO 0x00000004 /* Zero allocated hash table */
>
> /* Only NUMA needs hash distribution. 64bit NUMA architectures have
> diff --git a/kernel/futex/core.c b/kernel/futex/core.c
> index 514e4582b863..f10587d1d481 100644
> --- a/kernel/futex/core.c
> +++ b/kernel/futex/core.c
> @@ -1132,8 +1132,7 @@ static int __init futex_init(void)
> #endif
>
> futex_queues = alloc_large_system_hash("futex", sizeof(*futex_queues),
> - futex_hashsize, 0,
> - futex_hashsize < 256 ? HASH_SMALL : 0,
> + futex_hashsize, 0, 0,
> &futex_shift, NULL,
> futex_hashsize, futex_hashsize);
> futex_hashsize = 1UL << futex_shift;
> diff --git a/mm/mm_init.c b/mm/mm_init.c
> index d393631599a7..fab3c4649d5b 100644
> --- a/mm/mm_init.c
> +++ b/mm/mm_init.c
> @@ -2492,15 +2492,7 @@ void *__init alloc_large_system_hash(const char *tablename,
> else
> numentries <<= (PAGE_SHIFT - scale);
>
> - /* Make sure we've got at least a 0-order allocation.. */
> - if (unlikely(flags & HASH_SMALL)) {
> - /* Makes no sense without HASH_EARLY */
> - WARN_ON(!(flags & HASH_EARLY));
> - if (!(numentries >> *_hash_shift)) {
> - numentries = 1UL << *_hash_shift;
> - BUG_ON(!numentries);
> - }
> - } else if (unlikely((numentries * bucketsize) < PAGE_SIZE))
> + if (unlikely((numentries * bucketsize) < PAGE_SIZE))
> numentries = PAGE_SIZE / bucketsize;
> }
> numentries = roundup_pow_of_two(numentries);
> --
> 2.27.0
>
--
Sincerely yours,
Mike.
