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[PATCH] printk() should not be called under zone->lock

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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>
This commit is contained in:
Kirill Korotaev 2006-06-23 02:03:50 -07:00 committed by Linus Torvalds
parent d501e62bc7
commit 8f9de51a4a
1 changed files with 5 additions and 4 deletions
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9
mm/page_alloc.c
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@ -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));
}