[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/parisc/mm/init.c b/arch/parisc/mm/init.c
index 2886ad7..29b998e 100644
--- a/arch/parisc/mm/init.c
+++ b/arch/parisc/mm/init.c
@@ -505,7 +505,9 @@
for (j = node_start_pfn(i); j < node_end_pfn(i); j++) {
struct page *p;
+ unsigned long flags;
+ pgdat_resize_lock(NODE_DATA(i), &flags);
p = nid_page_nr(i, j) - node_start_pfn(i);
total++;
@@ -517,6 +519,7 @@
free++;
else
shared += page_count(p) - 1;
+ pgdat_resize_unlock(NODE_DATA(i), &flags);
}
}
#endif