Message-ID: <208eb79f-d064-36be-fece-a91007802379@linux.alibaba.com>
Date:   Wed, 15 Feb 2023 09:21:33 +0800
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Subject: Re: [PATCH v2 0/4] Change the return value for page isolation
 functions
To:     David Hildenbrand <david@redhat.com>, akpm@linux-foundation.org
Cc:     torvalds@linux-foundation.org, sj@kernel.org, hannes@cmpxchg.org,
        mhocko@kernel.org, roman.gushchin@linux.dev, shakeelb@google.com,
        muchun.song@linux.dev, naoya.horiguchi@nec.com,
        linmiaohe@huawei.com, osalvador@suse.de, mike.kravetz@oracle.com,
        willy@infradead.org, damon@lists.linux.dev,
        cgroups@vger.kernel.org, linux-mm@kvack.org,
        linux-kernel@vger.kernel.org
References: <cover.1676382188.git.baolin.wang@linux.alibaba.com>
 <5064ee08-792f-14f2-6f2d-26e81af8a239@redhat.com>
From:   Baolin Wang <baolin.wang@linux.alibaba.com>
In-Reply-To: <5064ee08-792f-14f2-6f2d-26e81af8a239@redhat.com>
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On 2/15/2023 1:52 AM, David Hildenbrand wrote:
> On 14.02.23 14:59, Baolin Wang wrote:
>> Now the page isolation functions did not return a boolean to indicate
>> success or not, instead it will return a negative error when failed
>> to isolate a page. So below code used in most places seem a boolean
>> success/failure thing, which can confuse people whether the isolation
>> is successful.
>>
>> if (folio_isolate_lru(folio))
>>          continue;
>>
>> Moreover the page isolation functions only return 0 or -EBUSY, and
>> most users did not care about the negative error except for few users,
>> thus we can convert all page isolation functions to return a boolean
>> value, which can remove the confusion to make code more clear.
>>
>> No functional changes intended in this patch series.
>>
>> Changes from v1:
>>   - Convert all isolation functions to return bool.
> 
> Acked-by: David Hildenbrand <david@redhat.com>

Thanks.

> 
> Although it's controversial if
> 
> if (!ret)
>      ret = -EBUSY;
> else
>      ret = 0;
> 
> is really appealing to the readers eye :)
> 
> ret = ret ? 0 : -EBUSY;
> 
> It's still confusing.
> 
> would be better as
> 
> ret = isolated ? 0 : -EBUSY;
> 
> IOW, not reusing the "int ret" variable.

Yes, pretty clear. Will do in next version.