On 2023/6/17 18:51, Mike Rapoport wrote:
> On Sat, Jun 17, 2023 at 04:39:44PM +0800, Miaohe Lin wrote:
>> On 2023/6/17 15:56, Mike Rapoport wrote:
>>> 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.
>>>
>>
>> Thanks for your quick review.
>>
>>> Doesn't it?
>>> What happens when CONFIG_BASE_SMALL is set?
>>
>> When CONFIG_BASE_SMALL is set, futex_hashsize is set to 16 and alloc_large_system_hash() is called with
>> numentries == 16 && flags == HASH_SMALL. But in the alloc_large_system_hash(), we have the below logic:
>>
>> alloc_large_system_hash()
>> {
>> if (!numentries) { /* numentries == 16 here, so this code block is skipped. */
>> ...
>> if (unlikely(flags & HASH_SMALL)) { /* So as here. */
>> ...
>> }
>> ...
>> }
>>
>> So HASH_SMALL is just unused. Or am I miss something?
>
> You are right, I've missed that.
>
>> Thanks.
>>
>>>
>>>> So HASH_SMALL is obsolete and remove it.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 */
>
> Can you update HASH_ZERO to 0x2?
Will do. Thanks.
