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 <[email protected]>
--- linux-2.6.17-rc6-mm1s.orig/mm/page_alloc.c 2006-06-09 15:37:09.000000000 +0400
+++ linux-2.6.16-rc6-mm1/mm/page_alloc.c 2006-06-15 12:42:31.000000000 +0400
@@ -1580,7 +1580,7 @@ void show_free_areas(void)
}
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);
@@ -1591,11 +1591,12 @@ void show_free_areas(void)
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));
}
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