Commit 8f9de51a authored by Kirill Korotaev's avatar Kirill Korotaev Committed by Linus Torvalds

[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: default avatarKirill Korotaev <dev@openvz.org>
Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
parent d501e62b
...@@ -1491,7 +1491,7 @@ void show_free_areas(void) ...@@ -1491,7 +1491,7 @@ void show_free_areas(void)
} }
for_each_zone(zone) { for_each_zone(zone) {
unsigned long nr, flags, order, total = 0; unsigned long nr[MAX_ORDER], flags, order, total = 0;
show_node(zone); show_node(zone);
printk("%s: ", zone->name); printk("%s: ", zone->name);
...@@ -1502,11 +1502,12 @@ void show_free_areas(void) ...@@ -1502,11 +1502,12 @@ void show_free_areas(void)
spin_lock_irqsave(&zone->lock, flags); spin_lock_irqsave(&zone->lock, flags);
for (order = 0; order < MAX_ORDER; order++) { for (order = 0; order < MAX_ORDER; order++) {
nr = zone->free_area[order].nr_free; nr[order] = zone->free_area[order].nr_free;
total += nr << order; total += nr[order] << order;
printk("%lu*%lukB ", nr, K(1UL) << order);
} }
spin_unlock_irqrestore(&zone->lock, flags); 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)); printk("= %lukB\n", K(total));
} }
......
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