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Date: Wed, 2 Jul 2014 13:33:58 -0400 From: Luiz Capitulino <lcapitulino@...hat.com> To: David Rientjes <rientjes@...gle.com> Cc: linux-mm@...ck.org, linux-kernel@...r.kernel.org, isimatu.yasuaki@...fujitsu.com, yinghai@...nel.org, riel@...hat.com, andi@...stfloor.org, akpm@...ux-foundation.org Subject: Re: [PATCH] x86: numa: setup_node_data(): drop dead code and rename function On Mon, 30 Jun 2014 16:42:39 -0700 (PDT) David Rientjes <rientjes@...gle.com> wrote: > On Thu, 19 Jun 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 > > different values. This means that the initialization done by > > 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 0x7ffec000-0x7ffeffff] > > [ 0.000000] Initmem setup node 1 [mem 0x80800000-0x1081fffff] > > [ 0.000000] NODE_DATA [mem 0x1081fa000-0x1081fdfff] > > [ 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 0x7ffec000-0x7ffeffff] > > [ 0.000000] NODE_DATA(1) allocated [mem 0x1081fa000-0x1081fdfff] > > [ 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] Node 0 memory range 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] Node 1 memory range 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@...hat.com> > > With this patch, the dmesg changes break one of my scripts that we use to > determine the start and end address of a node (doubly bad because there's > no sysfs interface to determine this otherwise and we have to do this at > boot to acquire the system topology). > > Specifically, the removal of the > > "Initmem setup node X [mem 0xstart-0xend]" > > lines that are replaced when each node is onlined to > > "Node 0 memory range 0xstart-0xend" > > And if I just noticed this breakage when booting the latest -mm kernel, > I'm assuming I'm not the only person who is going to run into it. Is it > possible to not change the dmesg output? Sure. I can add back the original text. The only detail is that with this patch that line is now printed a little bit later during boot and the NODA_DATA lines also changed. Are you OK with that? What's the guidelines on changing what's printed in dmesg? -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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