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Date:   Tue, 8 Jun 2021 13:32:21 +0100
From:   Matthew Wilcox <willy@infradead.org>
To:     "Kirill A. Shutemov" <kirill@shutemov.name>
Cc:     Xu Yu <xuyu@linux.alibaba.com>, linux-mm@kvack.org,
        linux-kernel@vger.kernel.org, hughd@google.com,
        akpm@linux-foundation.org, gavin.dg@linux.alibaba.com
Subject: Re: [PATCH v2] mm, thp: use head page in __migration_entry_wait
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References: <b9836c1dd522e903891760af9f0c86a2cce987eb.1623144009.git.xuyu@linux.alibaba.com>
 <20210608120026.ugfh72ydjeba44bo@box.shutemov.name>
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On Tue, Jun 08, 2021 at 03:00:26PM +0300, Kirill A. Shutemov wrote:
> But there's one quirk: if split succeed we effectively wait on wrong
> page to be unlocked. And it may take indefinite time if split_huge_page()
> was called on the head page.

Hardly indefinite time ... callers of split_huge_page_to_list() usually
unlock the page soon after.  Actually, I can't find one that doesn't call
unlock_page() within a few lines of calling split_huge_page_to_list().