On 07/12/18 at 09:19am, Chao Fan wrote:
> On Wed, Jul 11, 2018 at 08:40:08PM +0800, Baoquan He wrote:
> >Please try this v3 patch:
> >
> >From 9850d3de9c02e570dc7572069a9749a8add4c4c7 Mon Sep 17 00:00:00 2001
> >From: Baoquan He <b...@redhat.com>
> >Date: Wed, 11 Jul 2018 20:31:51 +0800
> >Subject: [PATCH v3] 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 on that node.
> >
> >Signed-off-by: Baoquan He <b...@redhat.com>
> >---
> > mm/page_alloc.c | 20 +++++++++++++++-----
> > 1 file changed, 15 insertions(+), 5 deletions(-)
> >
> >diff --git a/mm/page_alloc.c b/mm/page_alloc.c
> >index 1521100..390eb35 100644
> >--- a/mm/page_alloc.c
> >+++ b/mm/page_alloc.c
> >@@ -6547,7 +6547,7 @@ static unsigned long __init
> >early_calculate_totalpages(void)
> > static void __init find_zone_movable_pfns_for_nodes(void)
> > {
> > int i, nid;
> >- unsigned long usable_startpfn;
> >+ unsigned long usable_startpfn, real_startpfn;
> > unsigned long kernelcore_node, kernelcore_remaining;
> > /* save the state before borrow the nodemask */
> > nodemask_t saved_node_state = node_states[N_MEMORY];
> >@@ -6681,10 +6681,20 @@ static void __init
> >find_zone_movable_pfns_for_nodes(void)
> > if (start_pfn >= end_pfn)
> > continue;
>
> Hi Baoquan,
>
> Thanks for your quick reply and PATCH.
> I think it can work well after reviewing the code. But I think the new
> variable 'real_startpfn' is unnecessary. How about this:
>
> diff --git a/mm/page_alloc.c b/mm/page_alloc.c
> index 6d00f746c2fd..0fc9c4283947 100644
> --- a/mm/page_alloc.c
> +++ b/mm/page_alloc.c
> @@ -6492,6 +6492,10 @@ static void __init
> find_zone_movable_pfns_for_nodes(void)
> if (start_pfn >= end_pfn)
> continue;
>
> + if (pfn_to_nid(PFN_UP(_etext)) == i)
> + usable_startpfn = max(usable_startpfn,
> + PFN_UP(_etext));
> +
> /* Account for what is only usable for kernelcore */
> if (start_pfn < usable_startpfn) {
> unsigned long kernel_pages;
>
> I think the logic of these two method are the same, and this method
> change less code. If I am wrong, please let me know.
Might be not. Need consider usable_startpfn and kernel_pfn are in the
same node, or in different node, two cases.
I will correct code after fix the compiling error.
>
>
> >
> >+ /*
> >+ * KASLR may put kernel near tail of node memory,
> >+ * start after kernel on that node to find PFN
> >+ * which zone begins.
> >+ */
> >+ if (pfn_to_nid(PFN_UP(_etext)) == i)
> >+ real_startpfn = max(usable_startpfn,
> >+ PFN_UP(_etext))
> >+ else
> >+ real_startpfn = usable_startpfn;
> > /* Account for what is only usable for kernelcore */
> >- if (start_pfn < usable_startpfn) {
> >+ if (start_pfn < real_startpfn) {
> > unsigned long kernel_pages;
> >- kernel_pages = min(end_pfn, usable_startpfn)
> >+ kernel_pages = min(end_pfn, real_startpfn)
> > - start_pfn;
> >
> > kernelcore_remaining -= min(kernel_pages,
> >@@ -6693,7 +6703,7 @@ static void __init
> >find_zone_movable_pfns_for_nodes(void)
> > required_kernelcore);
> >
> > /* Continue if range is now fully accounted */
> >- if (end_pfn <= usable_startpfn) {
> >+ if (end_pfn <= real_startpfn) {
> >
> > /*
> > * Push zone_movable_pfn to the end so
> >@@ -6704,7 +6714,7 @@ static void __init
> >find_zone_movable_pfns_for_nodes(void)
> > zone_movable_pfn[nid] = end_pfn;
> > continue;
> > }
> >- start_pfn = usable_startpfn;
> >+ start_pfn = real_startpfn;
> > }
> >
> > /*
> >--
> >2.1.0
> >
> >
> >
>
>
