linux-kernel - Re: [PATCH] mm: hugepage: mark splitted page dirty when needed

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Message-ID: <20180904080115.o2zj4mlo7yzjdqfl@kshutemo-mobl1>
Date:   Tue, 4 Sep 2018 11:01:16 +0300
From:   "Kirill A. Shutemov" <kirill@...temov.name>
To:     Peter Xu <peterx@...hat.com>
Cc:     linux-kernel@...r.kernel.org,
        Andrea Arcangeli <aarcange@...hat.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>,
        Michal Hocko <mhocko@...e.com>, Zi Yan <zi.yan@...rutgers.edu>,
        Huang Ying <ying.huang@...el.com>,
        Dan Williams <dan.j.williams@...el.com>,
        Naoya Horiguchi <n-horiguchi@...jp.nec.com>,
        Jérôme Glisse <jglisse@...hat.com>,
        "Aneesh Kumar K.V" <aneesh.kumar@...ux.vnet.ibm.com>,
        Konstantin Khlebnikov <khlebnikov@...dex-team.ru>,
        Souptick Joarder <jrdr.linux@...il.com>, linux-mm@...ck.org
Subject: Re: [PATCH] mm: hugepage: mark splitted page dirty when needed

On Tue, Sep 04, 2018 at 03:55:10PM +0800, Peter Xu wrote:
> When splitting a huge page, we should set all small pages as dirty if
> the original huge page has the dirty bit set before.  Otherwise we'll
> lose the original dirty bit.

We don't lose it. It got transfered to struct page flag:

	if (pmd_dirty(old_pmd))
		SetPageDirty(page);

-- 
 Kirill A. Shutemov