Hi, Chen,
On 09/27/2012 09:19 PM, Ni zhan Chen wrote:
> On 09/27/2012 02:47 PM, Lai Jiangshan wrote:
>> The __add_zone() maybe call sleep-able init_currently_empty_zone()
>> to init wait_table,
>>
>> But this function also modifies the zone_start_pfn without any lock.
>> It is bugy.
>>
>> So we move this modification out, and we ensure the modification
>> of zone_start_pfn is only done with zone_span_writelock() held or in booting.
>>
>> Since zone_start_pfn is not modified by init_currently_empty_zone()
>> grow_zone_span() needs to check zone_start_pfn before update it.
>>
>> CC: Mel Gorman <m...@csn.ul.ie>
>> Signed-off-by: Lai Jiangshan <la...@cn.fujitsu.com>
>> Reported-by: Yasuaki ISIMATU <isimatu.yasu...@jp.fujitsu.com>
>> Tested-by: Wen Congyang <we...@cn.fujitsu.com>
>> ---
>> mm/memory_hotplug.c | 2 +-
>> mm/page_alloc.c | 3 +--
>> 2 files changed, 2 insertions(+), 3 deletions(-)
>>
>> diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
>> index b62d429b..790561f 100644
>> --- a/mm/memory_hotplug.c
>> +++ b/mm/memory_hotplug.c
>> @@ -205,7 +205,7 @@ static void grow_zone_span(struct zone *zone, unsigned
>> long start_pfn,
>> zone_span_writelock(zone);
>> old_zone_end_pfn = zone->zone_start_pfn + zone->spanned_pages;
>> - if (start_pfn < zone->zone_start_pfn)
>> + if (!zone->zone_start_pfn || start_pfn < zone->zone_start_pfn)
>> zone->zone_start_pfn = start_pfn;
>> zone->spanned_pages = max(old_zone_end_pfn, end_pfn) -
>> diff --git a/mm/page_alloc.c b/mm/page_alloc.c
>> index c13ea75..2545013 100644
>> --- a/mm/page_alloc.c
>> +++ b/mm/page_alloc.c
>> @@ -3997,8 +3997,6 @@ int __meminit init_currently_empty_zone(struct zone
>> *zone,
>> return ret;
>> pgdat->nr_zones = zone_idx(zone) + 1;
>> - zone->zone_start_pfn = zone_start_pfn;
>> -
>
> then how can mminit_dprintk print zone->zone_start_pfn ? always print 0 make
> no sense.
The full code here:
mminit_dprintk(MMINIT_TRACE, "memmap_init",
"Initialising map node %d zone %lu pfns %lu -> %lu\n",
pgdat->node_id,
(unsigned long)zone_idx(zone),
zone_start_pfn, (zone_start_pfn + size));
It doesn't always print 0, it still behaves as I expected.
Could you elaborate?
Thanks,
Lai
>
>> mminit_dprintk(MMINIT_TRACE, "memmap_init",
>> "Initialising map node %d zone %lu pfns %lu -> %lu\n",
>> pgdat->node_id,
>> @@ -4465,6 +4463,7 @@ static void __paginginit free_area_init_core(struct
>> pglist_data *pgdat,
>> ret = init_currently_empty_zone(zone, zone_start_pfn,
>> size, MEMMAP_EARLY);
>> BUG_ON(ret);
>> + zone->zone_start_pfn = zone_start_pfn;
>> memmap_init(size, nid, j, zone_start_pfn);
>> zone_start_pfn += size;
>> }
>
>
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