On Mon, 15 Sep 2014, Luiz Capitulino wrote: > The setup_node_data() function allocates a pg_data_t object, inserts it > into the node_data[] array and initializes the following fields: node_id, > node_start_pfn and node_spanned_pages. > > However, a few function calls later during the kernel boot, > free_area_init_node() re-initializes those fields, possibly with > setup_node_data() is not used. > > This causes a small glitch when running Linux as a hyperv numa guest: > > [ 0.000000] SRAT: PXM 0 -> APIC 0x00 -> Node 0 > [ 0.000000] SRAT: PXM 0 -> APIC 0x01 -> Node 0 > [ 0.000000] SRAT: PXM 1 -> APIC 0x02 -> Node 1 > [ 0.000000] SRAT: PXM 1 -> APIC 0x03 -> Node 1 > [ 0.000000] SRAT: Node 0 PXM 0 [mem 0x00000000-0x7fffffff] > [ 0.000000] SRAT: Node 1 PXM 1 [mem 0x80200000-0xf7ffffff] > [ 0.000000] SRAT: Node 1 PXM 1 [mem 0x100000000-0x1081fffff] > [ 0.000000] NUMA: Node 1 [mem 0x80200000-0xf7ffffff] + [mem 0x100000000-0x1081fffff] -> [mem 0x80200000-0x1081fffff] > [ 0.000000] Initmem setup node 0 [mem 0x00000000-0x7fffffff] > [ 0.000000] NODE_DATA [mem 0x7ffdc000-0x7ffeffff] > [ 0.000000] Initmem setup node 1 [mem 0x80800000-0x1081fffff] > [ 0.000000] NODE_DATA [mem 0x1081ea000-0x1081fdfff] > [ 0.000000] crashkernel: memory value expected > [ 0.000000] [ffffea0000000000-ffffea0001ffffff] PMD -> [ffff88007de00000-ffff88007fdfffff] on node 0 > [ 0.000000] [ffffea0002000000-ffffea00043fffff] PMD -> [ffff880105600000-ffff8801077fffff] on node 1 > [ 0.000000] Zone ranges: > [ 0.000000] DMA [mem 0x00001000-0x00ffffff] > [ 0.000000] DMA32 [mem 0x01000000-0xffffffff] > [ 0.000000] Normal [mem 0x100000000-0x1081fffff] > [ 0.000000] Movable zone start for each node > [ 0.000000] Early memory node ranges > [ 0.000000] node 0: [mem 0x00001000-0x0009efff] > [ 0.000000] node 0: [mem 0x00100000-0x7ffeffff] > [ 0.000000] node 1: [mem 0x80200000-0xf7ffffff] > [ 0.000000] node 1: [mem 0x100000000-0x1081fffff] > [ 0.000000] On node 0 totalpages: 524174 > [ 0.000000] DMA zone: 64 pages used for memmap > [ 0.000000] DMA zone: 21 pages reserved > [ 0.000000] DMA zone: 3998 pages, LIFO batch:0 > [ 0.000000] DMA32 zone: 8128 pages used for memmap > [ 0.000000] DMA32 zone: 520176 pages, LIFO batch:31 > [ 0.000000] On node 1 totalpages: 524288 > [ 0.000000] DMA32 zone: 7672 pages used for memmap > [ 0.000000] DMA32 zone: 491008 pages, LIFO batch:31 > [ 0.000000] Normal zone: 520 pages used for memmap > [ 0.000000] Normal zone: 33280 pages, LIFO batch:7 > > In this dmesg, the SRAT table reports that the memory range for node 1 > starts at 0x80200000. However, the line starting with "Initmem" reports > that node 1 memory range starts at 0x80800000. The "Initmem" line is > reported by setup_node_data() and is wrong, because the kernel ends up > using the range as reported in the SRAT table. > > This commit drops all that dead code from setup_node_data(), renames it to > alloc_node_data() and adds a printk() to free_area_init_node() so that we > report a node's memory range accurately. > > Here's the same dmesg section with this patch applied: > > [ 0.000000] SRAT: PXM 0 -> APIC 0x00 -> Node 0 > [ 0.000000] SRAT: PXM 0 -> APIC 0x01 -> Node 0 > [ 0.000000] SRAT: PXM 1 -> APIC 0x02 -> Node 1 > [ 0.000000] SRAT: PXM 1 -> APIC 0x03 -> Node 1 > [ 0.000000] SRAT: Node 0 PXM 0 [mem 0x00000000-0x7fffffff] > [ 0.000000] SRAT: Node 1 PXM 1 [mem 0x80200000-0xf7ffffff] > [ 0.000000] SRAT: Node 1 PXM 1 [mem 0x100000000-0x1081fffff] > [ 0.000000] NUMA: Node 1 [mem 0x80200000-0xf7ffffff] + [mem 0x100000000-0x1081fffff] -> [mem 0x80200000-0x1081fffff] > [ 0.000000] NODE_DATA(0) allocated [mem 0x7ffdc000-0x7ffeffff] > [ 0.000000] NODE_DATA(1) allocated [mem 0x1081ea000-0x1081fdfff] > [ 0.000000] crashkernel: memory value expected > [ 0.000000] [ffffea0000000000-ffffea0001ffffff] PMD -> [ffff88007de00000-ffff88007fdfffff] on node 0 > [ 0.000000] [ffffea0002000000-ffffea00043fffff] PMD -> [ffff880105600000-ffff8801077fffff] on node 1 > [ 0.000000] Zone ranges: > [ 0.000000] DMA [mem 0x00001000-0x00ffffff] > [ 0.000000] DMA32 [mem 0x01000000-0xffffffff] > [ 0.000000] Normal [mem 0x100000000-0x1081fffff] > [ 0.000000] Movable zone start for each node > [ 0.000000] Early memory node ranges > [ 0.000000] node 0: [mem 0x00001000-0x0009efff] > [ 0.000000] node 0: [mem 0x00100000-0x7ffeffff] > [ 0.000000] node 1: [mem 0x80200000-0xf7ffffff] > [ 0.000000] node 1: [mem 0x100000000-0x1081fffff] > [ 0.000000] Initmem setup node 0 [mem 0x00001000-0x7ffeffff] > [ 0.000000] On node 0 totalpages: 524174 > [ 0.000000] DMA zone: 64 pages used for memmap > [ 0.000000] DMA zone: 21 pages reserved > [ 0.000000] DMA zone: 3998 pages, LIFO batch:0 > [ 0.000000] DMA32 zone: 8128 pages used for memmap > [ 0.000000] DMA32 zone: 520176 pages, LIFO batch:31 > [ 0.000000] Initmem setup node 1 [mem 0x80200000-0x1081fffff] > [ 0.000000] On node 1 totalpages: 524288 > [ 0.000000] DMA32 zone: 7672 pages used for memmap > [ 0.000000] DMA32 zone: 491008 pages, LIFO batch:31 > [ 0.000000] Normal zone: 520 pages used for memmap > [ 0.000000] Normal zone: 33280 pages, LIFO batch:7 > > This commit was tested on a two node bare-metal NUMA machine and Linux as > a numa guest on hyperv and qemu/kvm. > > PS: The wrong memory range reported by setup_node_data() seems to be > harmless in the current kernel because it's just not used. However, > that bad range is used in kernel 2.6.32 to initialize the old boot > memory allocator, which causes a crash during boot. > > Signed-off-by: Luiz Capitulino <lcapitulino@xxxxxxxxxx> > Cc: Yasuaki Ishimatsu <isimatu.yasuaki@xxxxxxxxxxxxxx> > Cc: Yinghai Lu <yinghai@xxxxxxxxxx> > Acked-by: Rik van Riel <riel@xxxxxxxxxx> > Cc: Andi Kleen <andi@xxxxxxxxxxxxxx> > Cc: David Rientjes <rientjes@xxxxxxxxxx> > Cc: Ingo Molnar <mingo@xxxxxxx> > Cc: "H. Peter Anvin" <hpa@xxxxxxxxx> > Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx> > Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> > --- > > I posted this patch more than two months ago. Andrew picked it up and it > rested in the -mm tree for a couple of weeks. Andrew dropped it from -mm > to move it forward, but looks like it hasn't been picked by anyone else > since then. Resending... > This is still in linux-next-20140915 and I doubt it's 3.17 material so I'd wait for Andrew to take care of it. -- 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>