Received-SPF: pass (google.com: domain of linux-kernel+bounces-209224-linux.lists.archive=gmail.com@vger.kernel.org designates 147.75.80.249 as permitted sender) client-ip=147.75.80.249;
Message-ID: <1d951d46-8c80-4458-a1bf-b94680c451a6@linux.alibaba.com>
Date: Tue, 11 Jun 2024 11:38:31 +0800
Precedence: bulk
MIME-Version: 1.0
User-Agent: Mozilla Thunderbird
Subject: Re: [PATCH 5/7] mm: add new 'orders' parameter for find_get_entries()
 and find_lock_entries()
To: Matthew Wilcox <willy@infradead.org>
Cc: akpm@linux-foundation.org, hughd@google.com, david@redhat.com,
 wangkefeng.wang@huawei.com, chrisl@kernel.org, ying.huang@intel.com,
 21cnbao@gmail.com, ryan.roberts@arm.com, shy828301@gmail.com,
 ziy@nvidia.com, ioworker0@gmail.com, da.gomez@samsung.com,
 p.raghav@samsung.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org
References: <cover.1717673614.git.baolin.wang@linux.alibaba.com>
 <5304c4c54868336985b396d2c46132c2e0cdf803.1717673614.git.baolin.wang@linux.alibaba.com>
 <Zmcw-DymPwFcOqOY@casper.infradead.org>
From: Baolin Wang <baolin.wang@linux.alibaba.com>
In-Reply-To: <Zmcw-DymPwFcOqOY@casper.infradead.org>
Content-Type: text/plain; charset=UTF-8; format=flowed
Content-Transfer-Encoding: 7bit


On 2024/6/11 00:59, Matthew Wilcox wrote:
> On Thu, Jun 06, 2024 at 07:58:55PM +0800, Baolin Wang wrote:
>> In the following patches, shmem will support the swap out of large folios,
>> which means the shmem mappings may contain large order swap entries, so an
>> 'orders' array is added for find_get_entries() and find_lock_entries() to
>> obtain the order size of shmem swap entries, which will help in the release
>> of shmem large folio swap entries.
> 
> I am not a fan.

With Daniel's suggestion, I think I can drop the 'order' parameter if 
you don't like it.

I was hoping that 'order' would be encoded in the swap
> entry, not passed as a separate parameter.
> 
> As I understand it, we currently have a free bit, or
> swp_to_radix_entry() would not work.  We can use that as detailed
> here to encode the order in a single bit.
> 
> https://kernelnewbies.org/MatthewWilcox/NaturallyAlignedOrder

OK. This seems to deserve a separate patch set. I will look at your 
suggestion in detail. Thanks.