[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>
diff --git a/arch/ia64/mm/discontig.c b/arch/ia64/mm/discontig.c
index a3788fb..a88cdb7 100644
--- a/arch/ia64/mm/discontig.c
+++ b/arch/ia64/mm/discontig.c
@@ -555,9 +555,13 @@
show_free_areas();
printk("Free swap: %6ldkB\n", nr_swap_pages<<(PAGE_SHIFT-10));
for_each_pgdat(pgdat) {
- unsigned long present = pgdat->node_present_pages;
+ unsigned long present;
+ unsigned long flags;
int shared = 0, cached = 0, reserved = 0;
+
printk("Node ID: %d\n", pgdat->node_id);
+ pgdat_resize_lock(pgdat, &flags);
+ present = pgdat->node_present_pages;
for(i = 0; i < pgdat->node_spanned_pages; i++) {
struct page *page;
if (pfn_valid(pgdat->node_start_pfn + i))
@@ -571,6 +575,7 @@
else if (page_count(page))
shared += page_count(page)-1;
}
+ pgdat_resize_unlock(pgdat, &flags);
total_present += present;
total_reserved += reserved;
total_cached += cached;