From: Kirill Korotaev Date: Fri, 23 Jun 2006 09:03:50 +0000 (-0700) Subject: [PATCH] printk() should not be called under zone->lock X-Git-Tag: v2.6.18-rc1~1081^2~159 X-Git-Url: https://err.no/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=8f9de51a4a98ba32f839903b7d009788bc2c295d;p=linux-2.6 [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 Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- diff --git a/mm/page_alloc.c b/mm/page_alloc.c index 71a0b2a23f..423db0db7c 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -1491,7 +1491,7 @@ 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); @@ -1502,11 +1502,12 @@ 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)); }