On 09/28/2012 03:29 PM, Lai Jiangshan wrote:
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 <mel@xxxxxxxxx>
Signed-off-by: Lai Jiangshan <laijs@xxxxxxxxxxxxxx>
Reported-by: Yasuaki ISIMATU <isimatu.yasuaki@xxxxxxxxxxxxxx>
Tested-by: Wen Congyang <wency@xxxxxxxxxxxxxx>
---
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?
Yeah, you are right. I mean mminit_dprintk is called after
zone->zone_start_pfn initialized to show initialising state, but after
this patch applied zone->zone_start_pfn will not be initialized before
this print point.
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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