[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/m32r/mm/init.c b/arch/m32r/mm/init.c
index d9a40b1..6facf15 100644
--- a/arch/m32r/mm/init.c
+++ b/arch/m32r/mm/init.c
@@ -48,6 +48,8 @@
show_free_areas();
printk("Free swap: %6ldkB\n",nr_swap_pages<<(PAGE_SHIFT-10));
for_each_pgdat(pgdat) {
+ unsigned long flags;
+ pgdat_resize_lock(pgdat, &flags);
for (i = 0; i < pgdat->node_spanned_pages; ++i) {
page = pgdat_page_nr(pgdat, i);
total++;
@@ -60,6 +62,7 @@
else if (page_count(page))
shared += page_count(page) - 1;
}
+ pgdat_resize_unlock(pgdat, &flags);
}
printk("%d pages of RAM\n", total);
printk("%d pages of HIGHMEM\n",highmem);
@@ -150,10 +153,14 @@
int reservedpages, nid, i;
reservedpages = 0;
- for_each_online_node(nid)
+ for_each_online_node(nid) {
+ unsigned long flags;
+ pgdat_resize_lock(NODE_DATA(nid), &flags);
for (i = 0 ; i < MAX_LOW_PFN(nid) - START_PFN(nid) ; i++)
if (PageReserved(nid_page_nr(nid, i)))
reservedpages++;
+ pgdat_resize_unlock(NODE_DATA(nid), &flags);
+ }
return reservedpages;
}
