On Thu, Feb 06, 2020 at 09:50:16PM +0800, Baoquan He wrote:
>On 02/06/20 at 02:28pm, David Hildenbrand wrote:
>> 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@xxxxxxxxxxxxxxx>
>> > CC: Dan Williams <dan.j.williams@xxxxxxxxx>
>> > ---
>> > 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.
>
>It returns the pfn_to_page(pfn) from __populate_section_memmap() and
>assign to memmap in vmemmap case, how come it breaks anything. Correct
>me if I was wrong.
>
Just see your reply.
Thanks for your explanation. :-)
>> David / dhildenb
--
Wei Yang
Help you, Help me
