[PATCH] memory hotplug locking: node_size_lock

pgdat->node_size_lock is basically only neeeded in one place in the normal
code: show_mem(), which is the arch-specific sysrq-m printing function.

Strictly speaking, the architectures not doing memory hotplug do no need this
locking in show_mem().  However, they are all included for completeness.  This
should also make any future consolidation of all of the implementations a
little more straightforward.

This lock is also held in the sparsemem code during a memory removal, as
sections are invalidated.  This is the place there pfn_valid() is made false
for a memory area that's being removed.  The lock is only required when doing
pfn_valid() operations on memory which the user does not already have a
reference on the page, such as in show_mem().

Signed-off-by: Dave Hansen <haveblue@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 1 insertions, 0 deletions

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index a51ef94eec33..32fad6d23200 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -1958,6 +1958,7 @@ static void __init free_area_init_core(struct pglist_data *pgdat,
         int nid = pgdat->node_id;
         unsigned long zone_start_pfn = pgdat->node_start_pfn;
 
+        pgdat_resize_init(pgdat);
         pgdat->nr_zones = 0;
         init_waitqueue_head(&pgdat->kswapd_wait);
         pgdat->kswapd_max_order = 0;