linux-kernel - Re: [PATCH 1/7] mm/hugetlb: add folio support to hugetlb specific flag macros

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Date:   Tue, 30 Aug 2022 11:09:33 -0700
From:   Sidhartha Kumar <sidhartha.kumar@...cle.com>
To:     Matthew Wilcox <willy@...radead.org>
Cc:     linux-kernel@...r.kernel.org, linux-mm@...ck.org,
        akpm@...ux-foundation.org, songmuchun@...edance.com,
        mike.kravetz@...cle.com, vbabka@...e.cz,
        william.kucharski@...cle.com, dhowells@...hat.com,
        peterx@...hat.com, arnd@...db.de, ccross@...gle.com,
        hughd@...gle.com, ebiederm@...ssion.com
Subject: Re: [PATCH 1/7] mm/hugetlb: add folio support to hugetlb specific
 flag macros



On 8/29/22 8:33 PM, Matthew Wilcox wrote:
> On Mon, Aug 29, 2022 at 04:00:08PM -0700, Sidhartha Kumar wrote:
>>   #define TESTHPAGEFLAG(uname, flname)				\
>> +static __always_inline								\
>> +int folio_test_hugetlb_##flname(struct folio *folio)		\
> One change I made was to have folio_test_foo() return bool instead of
> int.  It helps the compiler really understand what's going on.  Maybe
> some humans too ;-)
>

I went with returning an int to stay consistent with the page version
of the macros which return an int. I'm fine with changing it to return
a bool.

>> +	{	void **private = &folio->private;		\
>> +		return test_bit(HPG_##flname, (void *)((unsigned long)private));	\
> I've made this tricky for you by making folio->private a void * instead
> of the unsigned long in page.  Would this look better as ...
>
> 	{							\
> 		void *private = &folio->private;		\
> 		return test_bit(HPG_##flname, private);		\
>
> perhaps?

Ya this looks much better and passes the tests, will add to v2.