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From: Muchun Song <muchun.song@linux.dev>
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Subject: Re: [PATCH 1/1] hugetlb: fix CONFIG_PADATA dependency for non-SMP system
Message-Id: <86B96EE5-A51C-4F06-BB18-0B3B12DBCCEC@linux.dev>
Date: Thu, 8 Feb 2024 10:39:13 +0800
Cc: Gang Li <ligang.bdlg@bytedance.com>,
 Andrew Morton <akpm@linux-foundation.org>, linux-kernel@vger.kernel.org,
 linux-mm@kvack.org, Randy Dunlap <rdunlap@infradead.org>,
 kernel test robot <lkp@intel.com>
To: Gang Li <gang.li@linux.dev>

=EF=BB=BF

> On Feb 5, 2024, at 16:08, Gang Li <gang.li@linux.dev> wrote:
>=20
> =EF=BB=BFOn 2024/2/5 15:37, Muchun Song wrote:
>> Actually, I did not get it. Why the above code cannot work? The above
>> code already make it serialized in one call, right? What do I miss here?
>> Thanks.
>=20
> PADATA consists of two distinct functionality:
>=20
> One part is `padata_do_multithreaded`, which disregards
> order and simply divides tasks into several groups for parallel
> execution. My patch use `padata_do_multithreaded`.

OK. Since all users of PADATA of non-SMP case currently only use padata_do_m=
ultithreaded, it=E2=80=99s possible and easy to implement a variant of that i=
n non-SMP case. It is not necessary to implement another functionality unles=
s the only user of crypto/pcrypt.c does not depend on SMP in the future, at l=
east now it=E2=80=99s dependent on SMP.

Thanks.

>=20
> The other part is composed of a set of APIs that, while handling data in
> an out-of-order parallel manner, can eventually return the data with
> ordered sequence. Only `crypto/pcrypt.c` use them. I guess these APIs
> are designed specifically for `crypto/pcrypt.c`.
> ```
> padata_alloc
> padata_alloc_shell
> padata_do_parallel
> padata_do_serial
> padata_free_shell
> padata_free
> ```