hi Robert,
On 2016/12/12 11:12, Yisheng Xie wrote:
> hi Robert,
>
> On 2016/12/10 2:10, Robert Richter wrote:
>> On ThunderX systems with certain memory configurations we see the
>> following BUG_ON():
>>
>> kernel BUG at mm/page_alloc.c:1848!
>>
>> This happens for some configs with 64k page size enabled. The BUG_ON()
>> checks if start and end page of a memmap range belongs to the same
>> zone.
>>
>> The BUG_ON() check fails if a memory zone contains NOMAP regions. In
>> this case the node information of those pages is not initialized. This
>> causes an inconsistency of the page links with wrong zone and node
>> information for that pages. NOMAP pages from node 1 still point to the
>> mem zone from node 0 and have the wrong nid assigned.
>>
> The patch can work for zone contains NOMAP regions.
>
> However, if BIOS do not add WB/WT/WC attribute to a physical address range, the
> is_memory(md) will return false and this range will not be added to memblock.
> efi_init
> -> reserve_regions
> if (is_memory(md)) {
> early_init_dt_add_memory_arch(paddr, size);
>
> if (!is_usable_memory(md))
> memblock_mark_nomap(paddr, size);
> }
>
> Then BUG_ON() check will also fails. Any idea about it?
>
It seems that memblock_is_memory() is also too strict for early_pfn_valid,
so what about this patch, which use common pfn_valid as early_pfn_valid
when CONFIG_HAVE_ARCH_PFN_VALID=y:
------------
diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h
index 0f088f3..9d596f3 100644
--- a/include/linux/mmzone.h
+++ b/include/linux/mmzone.h
@@ -1200,7 +1200,17 @@ static inline int pfn_present(unsigned long pfn)
#define pfn_to_nid(pfn) (0)
#endif
+#ifdef CONFIG_HAVE_ARCH_PFN_VALID
+static inline int early_pfn_valid(unsigned long pfn)
+{
+ if (pfn_to_section_nr(pfn) >= NR_MEM_SECTIONS)
+ return 0;
+ return valid_section(__nr_to_section(pfn_to_section_nr(pfn)));
+}
+#define early_pfn_valid early_pfn_valid
+#else
#define early_pfn_valid(pfn) pfn_valid(pfn)
+#endif
void sparse_init(void);
#else
#define sparse_init() do {} while (0)
--
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