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Date:   Tue, 14 Feb 2023 04:50:30 +0000
From:   Matthew Wilcox <willy@infradead.org>
To:     Baolin Wang <baolin.wang@linux.alibaba.com>
Cc:     akpm@linux-foundation.org, torvalds@linux-foundation.org,
        sj@kernel.org, hannes@cmpxchg.org, mhocko@kernel.org,
        roman.gushchin@linux.dev, shakeelb@google.com,
        muchun.song@linux.dev, damon@lists.linux.dev,
        cgroups@vger.kernel.org, linux-mm@kvack.org,
        linux-kernel@vger.kernel.org
Subject: Re: [PATCH 0/3] Some cleanups for page isolation
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References: <cover.1676342827.git.baolin.wang@linux.alibaba.com>
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On Tue, Feb 14, 2023 at 11:18:05AM +0800, Baolin Wang wrote:
> 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 it's better to check the negative error explicitly
> for isolation to make the code more clear per Linus's suggestion in [1].

Only one caller of isolate_lru_page() or folio_isolate_lru() actually
uses the errno.  And the errno can only be 0 or -EBUSY.  It'd be
better to change the three functions to return bool and fix
add_page_for_migration() to set the errno to -EBUSY itself.