Messages in this thread Patch in this message | | | From | Mel Gorman <> | Subject | [PATCH 1/3] powerpc: Allocate per-cpu areas for node IDs for SLQB to use as per-node areas | Date | Mon, 21 Sep 2009 17:10:24 +0100 |
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SLQB uses DEFINE_PER_CPU to define per-node areas. An implicit assumption is made that all valid node IDs will have matching valid CPU ids. In memoryless configurations, it is possible to have a node ID with no CPU having the same ID. When this happens, a per-cpu are is not created and the value of paca[cpu].data_offset is some random value. This is later deferenced and the system crashes after accessing some invalid address.
This patch hacks powerpc to allocate per-cpu areas for node IDs that have no corresponding CPU id. This gets around the immediate problem but it should be discussed if there is a requirement for a DEFINE_PER_NODE and how it should be implemented.
Signed-off-by: Mel Gorman <mel@csn.ul.ie> --- arch/powerpc/kernel/setup_64.c | 20 ++++++++++++++++++++ 1 files changed, 20 insertions(+), 0 deletions(-)
diff --git a/arch/powerpc/kernel/setup_64.c b/arch/powerpc/kernel/setup_64.c index 1f68160..a5f52d4 100644 --- a/arch/powerpc/kernel/setup_64.c +++ b/arch/powerpc/kernel/setup_64.c @@ -588,6 +588,26 @@ void __init setup_per_cpu_areas(void) paca[i].data_offset = ptr - __per_cpu_start; memcpy(ptr, __per_cpu_start, __per_cpu_end - __per_cpu_start); } +#ifdef CONFIG_SLQB + /* + * SLQB abuses DEFINE_PER_CPU to setup a per-node area. This trick + * assumes that ever node ID will have a CPU of that ID to match. + * On systems with memoryless nodes, this may not hold true. Hence, + * we take a second pass initialising a "per-cpu" area for node-ids + * that SLQB can use + */ + for_each_node_state(i, N_NORMAL_MEMORY) { + + /* Skip node IDs that a valid CPU id exists for */ + if (paca[i].data_offset) + continue; + + ptr = alloc_bootmem_pages_node(NODE_DATA(cpu_to_node(i)), size); + + paca[i].data_offset = ptr - __per_cpu_start; + memcpy(ptr, __per_cpu_start, __per_cpu_end - __per_cpu_start); + } +#endif /* CONFIG_SLQB */ } #endif -- 1.6.3.3
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