[PATCH] printk() should not be called under zone->lock
This patch fixes printk() under zone->lock in show_free_areas(). It can be
unsafe to call printk() under this lock, since caller can try to
allocate/free some memory and selfdeadlock on this lock. I found
allocations/freeing mem both in netconsole and serial console.
This issue was faced in reallity when meminfo was periodically printed for
debug purposes and netconsole was used.
Signed-off-by: Kirill Korotaev <dev@openvz.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 71a0b2a..423db0d 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -1491,7 +1491,7 @@
}
for_each_zone(zone) {
- unsigned long nr, flags, order, total = 0;
+ unsigned long nr[MAX_ORDER], flags, order, total = 0;
show_node(zone);
printk("%s: ", zone->name);
@@ -1502,11 +1502,12 @@
spin_lock_irqsave(&zone->lock, flags);
for (order = 0; order < MAX_ORDER; order++) {
- nr = zone->free_area[order].nr_free;
- total += nr << order;
- printk("%lu*%lukB ", nr, K(1UL) << order);
+ nr[order] = zone->free_area[order].nr_free;
+ total += nr[order] << order;
}
spin_unlock_irqrestore(&zone->lock, flags);
+ for (order = 0; order < MAX_ORDER; order++)
+ printk("%lu*%lukB ", nr[order], K(1UL) << order);
printk("= %lukB\n", K(total));
}