Commit 04d94879 authored Jan 10, 2011 by Christoph Lameter Committed by Pekka Enberg Jan 11, 2011

slub: Avoid use of slub_lock in show_slab_objects()



The purpose of the locking is to prevent removal and additions
of nodes when statistics are gathered for a slab cache. So we
need to avoid racing with memory hotplug functionality.

It is enough to take the memory hotplug locks there instead
of the slub_lock.

online_pages() currently does not acquire the memory_hotplug
lock. Another patch will be submitted by the memory hotplug
authors to take the memory hotplug lock and describe the
uses of the memory hotplug lock to protect against
adding and removal of nodes from non hotplug data structures.

Cc: <stable@kernel.org> # 2.6.37
Reported-and-tested-by: Bart Van Assche <bvanassche@acm.org>
Acked-by: David Rientjes <rientjes@google.com>
Signed-off-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>

parent 925268a0

mm/slub.c

+2 −2

Original line number	Diff line number	Diff line
		@@ -3821,7 +3821,7 @@ static ssize_t show_slab_objects(struct kmem_cache *s,
		}
		}

		down_read(&slub_lock);
		lock_memory_hotplug();
		#ifdef CONFIG_SLUB_DEBUG
		if (flags & SO_ALL) {
		for_each_node_state(node, N_NORMAL_MEMORY) {
		@@ -3862,7 +3862,7 @@ static ssize_t show_slab_objects(struct kmem_cache *s,
		x += sprintf(buf + x, " N%d=%lu",
		node, nodes[node]);
		#endif
		up_read(&slub_lock);
		unlock_memory_hotplug();
		kfree(nodes);
		return x + sprintf(buf + x, "\n");
		}

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