Hi David, thanks for the comments. See my answer please: > -----Original Message----- > From: David Hildenbrand <david@xxxxxxxxxx> > Sent: Monday, July 6, 2020 4:03 PM > To: Justin He <Justin.He@xxxxxxx>; Catalin Marinas > <Catalin.Marinas@xxxxxxx>; Will Deacon <will@xxxxxxxxxx> > Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>; Mike Rapoport > <rppt@xxxxxxxxxxxxx>; Baoquan He <bhe@xxxxxxxxxx>; Chuhong Yuan > <hslester96@xxxxxxxxx>; linux-arm-kernel@xxxxxxxxxxxxxxxxxxx; linux- > kernel@xxxxxxxxxxxxxxx; linux-mm@xxxxxxxxx; Kaly Xin <Kaly.Xin@xxxxxxx> > Subject: Re: [PATCH 1/3] arm64/numa: set numa_off to false when numa node > is fake > > On 06.07.20 03:19, Jia He wrote: > > Previously, numa_off is set to true unconditionally in dummy_numa_init(), > > even if there is a fake numa node. > > > > But acpi will translate node id to NUMA_NO_NODE(-1) in > acpi_map_pxm_to_node() > > because it regards numa_off as turning off the numa node. > > > > Without this patch, pmem can't be probed as a RAM device on arm64 if > SRAT table > > isn't present. > > > > $ndctl create-namespace -fe namespace0.0 --mode=devdax --map=dev -s 1g - > a 64K > > kmem dax0.0: rejecting DAX region [mem 0x240400000-0x2bfffffff] with > invalid node: -1 > > kmem: probe of dax0.0 failed with error -22 > > > > This fixes it by setting numa_off to false. > > > > Signed-off-by: Jia He <justin.he@xxxxxxx> > > --- > > arch/arm64/mm/numa.c | 3 ++- > > 1 file changed, 2 insertions(+), 1 deletion(-) > > > > diff --git a/arch/arm64/mm/numa.c b/arch/arm64/mm/numa.c > > index aafcee3e3f7e..7689986020d9 100644 > > --- a/arch/arm64/mm/numa.c > > +++ b/arch/arm64/mm/numa.c > > @@ -440,7 +440,8 @@ static int __init dummy_numa_init(void) > > return ret; > > } > > > > - numa_off = true; > > + /* force numa_off to be false since we have a fake numa node here > */ > > + numa_off = false; > > return 0; > > } > > > > > > What would happen if we use something like this in drivers/dax/kmem.c > instead: > > numa_node = dev_dax->target_node; > if (numa_node == NUMA_NO_NODE) > numa_node = memory_add_physaddr_to_nid(kmem_start); > > and eventually dropping the pr_warn in > arm64/memory_add_physaddr_to_nid() ? Would that work? Yes, it works. I sent a similar patch [1] before. But seems pmem maintainer didn't satisfy it. Do you think memory_add_physaddr_to_nid() is better than numa_mem_id()? [1] https://lkml.org/lkml/2019/8/16/367 -- Cheers, Justin (Jia He)
