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From:   Zi Yan <ziy@nvidia.com>
To:     Andrew Morton <akpm@linux-foundation.org>
Cc:     linux-mm@kvack.org, Matthew Wilcox <willy@infradead.org>,
        Michal Hocko <mhocko@kernel.org>,
        Naoya Horiguchi <naoya.horiguchi@nec.com>,
        linux-kernel@vger.kernel.org,
        Naoya Horiguchi <naoya.horiguchi@linux.dev>
Subject: Re: [PATCH] mm: migrate: use thp_order instead of HPAGE_PMD_ORDER for new page allocation.
Date:   Mon, 04 Apr 2022 14:37:41 -0400
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 <20220404112802.4c07585b7b7e420342c9b0fb@linux-foundation.org>
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On 4 Apr 2022, at 14:28, Andrew Morton wrote:

> On Mon,  4 Apr 2022 12:53:25 -0400 Zi Yan <zi.yan@sent.com> wrote:
>
>> From: Zi Yan <ziy@nvidia.com>
>>
>> With folios support, it is possible to have other than HPAGE_PMD_ORDER=

>> THPs, in the form of folios, in the system. Use thp_order() to correct=
ly
>> determine the source page order during migration.
>
> Changelog doesn't describe the end user visible effects of the bug.
> And it really should, because
>
>> Link: https://nam11.safelinks.protection.outlook.com/?url=3Dhttps%3A%2=
F%2Flore.kernel.org%2Flinux-mm%2F20220404132908.GA785673%40u2004%2F&amp;d=
ata=3D04%7C01%7Cziy%40nvidia.com%7Cbf27ebf19d8a49a9b4b008da1668dc09%7C430=
83d15727340c1b7db39efd9ccc17a%7C0%7C0%7C637846936880192108%7CUnknown%7CTW=
FpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0=
%3D%7C3000&amp;sdata=3DpgvzV3wv6icqkMaWY2koB9X4VqlPMaSHeB8r7%2Fv1938%3D&a=
mp;reserved=3D0
>
> it fixes a kernel crash!

Thank you for adding the information.

--
Best Regards,
Yan, Zi

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