Re: compaction: VM_BUG_ON_PAGE(!zone_spans_pfn(page_zone(page), pfn))

[Baoquan He]

Hi,

On 04/24/20 at 09:45am, Qian Cai wrote:
> 
> 
> > On Apr 23, 2020, at 11:43 PM, Baoquan He <b...@redhat.com> wrote:
> > 
> > On 04/23/20 at 05:25pm, Qian Cai wrote:
> >> Compaction starts to crash below on linux-next today. The faulty page 
> >> belongs to Node 0 DMA32 zone.
> >> I’ll continue to narrow it down, but just want to give a headup in case 
> >> someone could beat me to it.
> >> 
> >> Debug output from free_area_init_core()
> >> [    0.000000] KK start page = ffffea0000000040, end page = 
> >> ffffea0000040000, nid = 0 DMA
> >> [    0.000000] KK start page = ffffea0000040000, end page = 
> >> ffffea0004000000, nid = 0 DMA32
> >> [    0.000000] KK start page = ffffea0004000000, end page = 
> >> ffffea0012000000, nid = 0 NORMAL
> >> [    0.000000] KK start page = ffffea0012000000, end page = 
> >> ffffea0021fc0000, nid = 4 NORMAL
> > 
> > Where are these printed? They are the direct mapping address of page?
> 
> From this debug patch. Yes, direct mapping.

Can you try below patch? I may get why this is caused, not sure if the
place is right. 

diff --git a/mm/compaction.c b/mm/compaction.c
index 177c11a8f3b9..e26972f26414 100644
--- a/mm/compaction.c
+++ b/mm/compaction.c
@@ -1409,7 +1409,9 @@ fast_isolate_freepages(struct compact_control *cc)
                                cc->free_pfn = highest;
                        } else {
                                if (cc->direct_compaction && 
pfn_valid(min_pfn)) {
-                                       page = pfn_to_page(min_pfn);
+                                       page = pageblock_pfn_to_page(min_pfn,
+                                               pageblock_end_pfn(min_pfn),
+                                               cc->zone);
                                        cc->free_pfn = min_pfn;
                                }
                        }