linux-kernel - Re: 2.6.22-rc4-mm1

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Date:	Thu, 7 Jun 2007 21:47:06 +0900
From:	KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>
To:	Andrew Morton <akpm@...ux-foundation.org>
Cc:	linux-kernel@...r.kernel.org, clameter@....com,
	"linux-mm@...ck.org" <linux-mm@...ck.org>
Subject: Re: 2.6.22-rc4-mm1

Question.

While writing memory unplug, I noticed this code.
==
static int
fixup_anon_page(pte_t *pte, unsigned long start, unsigned long end, void *priv)
{
        struct vm_area_struct *vma = priv;
        struct page *page = vm_normal_page(vma, start, *pte);

        if (page && PageAnon(page))
                page->index = linear_page_index(vma, start);

        return 0;
}

static int fixup_anon_pages(struct vm_area_struct *vma)
{
        struct mm_walk walk = {
                .pte_entry = fixup_anon_page,
        };

        return walk_page_range(vma->vm_mm,
                        vma->vm_start, vma->vm_end, &walk, vma);
}
==

I think that 'pte' passed to fixup_anon_page() by walk_page_range()
is not guaranteed to be 'Present'.

Then, vm_normal_page() will show print_bad_pte().

If this never occur now, I'll add my own check code for memory migration by kernel here.

(Sorry, I can't find who should be CCed.)

-Kame


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