On 11/07/2012 11:25 PM, Mel Gorman wrote:
On Wed, Nov 07, 2012 at 05:27:12PM +0800, Zhouping Liu wrote:
Hello Mel,Early initialisation problem by the looks of things. Try this please
my 2 nodes machine hit a panic fault after applied the patch
set(based on kernel-3.7.0-rc4), please review it:
<SNIP>
Tested the patch, and the issue is gone.
---8<---
mm: numa: Check that preferred_node_policy is initialised
Zhouping Liu reported the following
[ 0.000000] ------------[ cut here ]------------
[ 0.000000] kernel BUG at mm/mempolicy.c:1785!
[ 0.000000] invalid opcode: 0000 [#1] SMP
[ 0.000000] Modules linked in:
[ 0.000000] CPU 0
....
[ 0.000000] Call Trace:
[ 0.000000] [<ffffffff81176966>] alloc_pages_current+0xa6/0x170
[ 0.000000] [<ffffffff81137a44>] __get_free_pages+0x14/0x50
[ 0.000000] [<ffffffff819efd9b>] kmem_cache_init+0x53/0x2d2
[ 0.000000] [<ffffffff819caa53>] start_kernel+0x1e0/0x3c7
Problem is that early in boot preferred_nod_policy and SLUB
initialisation trips up. Check it is initialised.
Signed-off-by: Mel Gorman <mgorman@suse.de>
Tested-by: Zhouping Liu <zliu@redhat.com>
Thanks,
Zhouping
---
mm/mempolicy.c | 4 ++++
1 file changed, 4 insertions(+)
diff --git a/mm/mempolicy.c b/mm/mempolicy.c
index 11d4b6b..8cfa6dc 100644
--- a/mm/mempolicy.c
+++ b/mm/mempolicy.c
@@ -129,6 +129,10 @@ static struct mempolicy *get_task_policy(struct task_struct *p)
node = numa_node_id();
if (node != -1)
pol = &preferred_node_policy[node];
+
+ /* preferred_node_policy is not initialised early in boot */
+ if (!pol->mode)
+ pol = NULL;
}
return pol;
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