On 2015/8/19 19:52, Robin Holt wrote: > On Sun, Aug 16, 2015 at 10:19 PM, Jiang Liu <jiang.liu@xxxxxxxxxxxxxxx> wrote: >> Function xpc_create_gru_mq_uv() allocates memory with __GFP_THISNODE >> flag set, which may cause permanent memory allocation failure on >> memoryless node. So replace cpu_to_node() with cpu_to_mem() to better >> support memoryless node. For node with memory, cpu_to_mem() is the same >> as cpu_to_node(). >> >> Signed-off-by: Jiang Liu <jiang.liu@xxxxxxxxxxxxxxx> >> --- >> drivers/misc/sgi-xp/xpc_uv.c | 2 +- >> 1 file changed, 1 insertion(+), 1 deletion(-) >> >> diff --git a/drivers/misc/sgi-xp/xpc_uv.c b/drivers/misc/sgi-xp/xpc_uv.c >> index 95c894482fdd..9210981c0d5b 100644 >> --- a/drivers/misc/sgi-xp/xpc_uv.c >> +++ b/drivers/misc/sgi-xp/xpc_uv.c >> @@ -238,7 +238,7 @@ xpc_create_gru_mq_uv(unsigned int mq_size, int cpu, char *irq_name, >> >> mq->mmr_blade = uv_cpu_to_blade_id(cpu); >> >> - nid = cpu_to_node(cpu); >> + nid = cpu_to_mem(cpu); > > I would recommend rejecting this. First, SGI's UV system does not and > can not support memory-less nodes. Additionally the hardware _REALLY_ > wants the memory to be local to the CPU. We will register this memory > region with the node firmware. That will set the hardware up to watch > this memory block and raise an IRQ targeting the registered CPU when > anything is written into the memory block. This is all part of how > cross-partition communications expects to work. > > Additionally, the interrupt handler will read the memory region, so > having node-local memory is extremely helpful. Hi Robin, Thanks for review, I will drop this patch in next version. Actually, if SGI UV systems don't support memoryless node, cpu_to_mem() is the same as cpu_to_node(). Thanks! Gerry > > Thanks, > Robin > -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>