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SubjectRe: Bug report about KASLR and ZONE_MOVABLE
On 07/11/18 at 06:49pm, Baoquan He wrote:
> On 07/11/18 at 06:41pm, Baoquan He wrote:
> > diff --git a/mm/page_alloc.c b/mm/page_alloc.c
> > index 1521100..fe346b4 100644
> > --- a/mm/page_alloc.c
> > +++ b/mm/page_alloc.c
> > @@ -6678,6 +6678,8 @@ static void __init find_zone_movable_pfns_for_nodes(void)
> > unsigned long size_pages;
> >
> > start_pfn = max(start_pfn, zone_movable_pfn[nid]);
> > + /* KASLR may put kernel after 'start_pfn', start after kernel */
> > + start_pfn = max(start_pfn, PAGE_ALIGN(_etext));
>
> Sorry, I used wrong function.
>
> Please try this one:
>
> From 005435407a331ecf2803e5ebfdc44b8f5f8f9748 Mon Sep 17 00:00:00 2001
> From: Baoquan He <bhe@redhat.com>
> Date: Wed, 11 Jul 2018 18:30:04 +0800
> Subject: [PATCH v2] mm, page_alloc: find movable zone after kernel text
>
> In find_zone_movable_pfns_for_nodes(), when try to find the starting
> PFN movable zone begins in each node, kernel text position is not
> considered. KASLR may put kernel after which movable zone begins.
>
> Fix it by finding movable zone after kernel text.
>
> Signed-off-by: Baoquan He <bhe@redhat.com>
> ---
> mm/page_alloc.c | 2 ++
> 1 file changed, 2 insertions(+)
>
> diff --git a/mm/page_alloc.c b/mm/page_alloc.c
> index 1521100..17584cc 100644
> --- a/mm/page_alloc.c
> +++ b/mm/page_alloc.c
> @@ -6678,6 +6678,8 @@ static void __init find_zone_movable_pfns_for_nodes(void)
> unsigned long size_pages;
>
> start_pfn = max(start_pfn, zone_movable_pfn[nid]);
> + /* KASLR may put kernel after 'start_pfn', start after kernel */
> + start_pfn = max(start_pfn, PFN_UP(_etext));

It's wrong again, NACK, have posted v3 in this thread.

> if (start_pfn >= end_pfn)
> continue;
>
> --
> 2.1.0
>

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