Messages in this thread | | | Subject | Re: [PATCH] mm/sparsemem: pfn_to_page is not valid yet on SPARSEMEM | From | David Hildenbrand <> | Date | Thu, 6 Feb 2020 14:28:53 +0100 |
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On 06.02.20 13:53, Wei Yang wrote: > When we use SPARSEMEM instead of SPARSEMEM_VMEMMAP, pfn_to_page() > doesn't work before sparse_init_one_section() is called. This leads to a > crash when hotplug memory. > > We should use memmap as it did. > > Fixes: ba72b4c8cf60 ("mm/sparsemem: support sub-section hotplug") > Signed-off-by: Wei Yang <richardw.yang@linux.intel.com> > CC: Dan Williams <dan.j.williams@intel.com> > --- > mm/sparse.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/mm/sparse.c b/mm/sparse.c > index 5a8599041a2a..2efb24ff8f96 100644 > --- a/mm/sparse.c > +++ b/mm/sparse.c > @@ -882,7 +882,7 @@ int __meminit sparse_add_section(int nid, unsigned long start_pfn, > * Poison uninitialized struct pages in order to catch invalid flags > * combinations. > */ > - page_init_poison(pfn_to_page(start_pfn), sizeof(struct page) * nr_pages); > + page_init_poison(memmap, sizeof(struct page) * nr_pages);
If you add sub-sections that don't fall onto the start of the section,
pfn_to_page(start_pfn) != memmap
and your patch would break that under SPARSEMEM_VMEMMAP if I am not wrong.
Instead of memmap, there would have to be something like
memmap + (start_pfn - SECTION_ALIGN_DOWN(start_pfn))
If I am not wrong :)
-- Thanks,
David / dhildenb
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