Messages in this thread | | | From | Johannes Weiner <> | Subject | Re: [patch] mm: node-setup agnostic free_bootmem() | Date | Wed, 30 Apr 2008 19:52:17 +0200 |
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Hi,
"Yinghai Lu" <yhlu.kernel@gmail.com> writes:
> On Wed, Apr 30, 2008 at 3:50 AM, Johannes Weiner <hannes@saeurebad.de> wrote: >> >> Hi, >> >> "Yinghai Lu" <yhlu.kernel@gmail.com> writes: >> >> > On Mon, Apr 28, 2008 at 12:11 PM, Yinghai Lu <yhlu.kernel@gmail.com> wrote: >> >> >> >> On Mon, Apr 28, 2008 at 9:54 AM, Johannes Weiner <hannes@saeurebad.de> wrote: >> >> > Hi Yinghai, >> >> > >> >> > >> >> > >> >> > "Yinghai Lu" <yhlu.kernel@gmail.com> writes: >> >> > >> >> > > On Sun, Apr 27, 2008 at 5:40 PM, Ingo Molnar <mingo@elte.hu> wrote: >> >> > >> >> >> > >> * Johannes Weiner <hannes@saeurebad.de> wrote: >> >> > >> >> >> > >> > > so i very much agree that your changes are cleaner, i just wanted to >> >> > >> > > have one that has all the fixes included. >> >> > >> > >> >> > >> > I had planned this to be another patch because there are more then one >> >> > >> > boundary check I wanted to tighten. I can merge them though if you >> >> > >> > like. >> >> > >> >> >> > >> no, better to have them in separate patches. >> >> > >> >> >> > >> > > Would you like to post a patch against current -git or should i >> >> > >> > > extract the cleaner reserve_bootmem() from your previous patch? >> >> > >> > >> >> > >> > I just moved and have only sporadic internet access and free time >> >> > >> > slots available. Would be nice if you could do it! >> >> > >> >> >> > >> sure, find the merged patch below, against latest -git, boot-tested on >> >> > >> x86. Is this what you had in mind? >> >> > >> >> >> > >> Ingo >> >> > >> >> >> > >> ----------------> >> >> > >> Subject: mm: node-setup agnostic free_bootmem() >> >> > >> From: Johannes Weiner <hannes@saeurebad.de> >> >> > >> Date: Wed, 16 Apr 2008 13:36:31 +0200 >> >> > >> >> >> > >> Make free_bootmem() look up the node holding the specified address >> >> > >> range which lets it work transparently on single-node and multi-node >> >> > >> configurations. >> >> > >> >> >> > >> If the address range exceeds the node range, it well be marked free >> >> > >> across node boundaries, too. >> >> > >> >> >> > >> Signed-off-by: Johannes Weiner <hannes@saeurebad.de> >> >> > >> CC: Andi Kleen <andi@firstfloor.org> >> >> > >> CC: Yinghai Lu <yhlu.kernel@gmail.com> >> >> > >> CC: Yasunori Goto <y-goto@jp.fujitsu.com> >> >> > >> CC: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> >> >> > >> CC: Christoph Lameter <clameter@sgi.com> >> >> > >> CC: Andrew Morton <akpm@linux-foundation.org> >> >> > >> Signed-off-by: Ingo Molnar <mingo@elte.hu> >> >> > >> --- >> >> > >> mm/bootmem.c | 27 +++++++++++++++++++++++++-- >> >> > >> 1 file changed, 25 insertions(+), 2 deletions(-) >> >> > >> >> >> > >> Index: linux-x86.q/mm/bootmem.c >> >> > >> =================================================================== >> >> > >> --- linux-x86.q.orig/mm/bootmem.c >> >> > >> +++ linux-x86.q/mm/bootmem.c >> >> > >> @@ -493,8 +493,31 @@ int __init reserve_bootmem(unsigned long >> >> > >> void __init free_bootmem(unsigned long addr, unsigned long size) >> >> > >> { >> >> > >> bootmem_data_t *bdata; >> >> > >> - list_for_each_entry(bdata, &bdata_list, list) >> >> > >> - free_bootmem_core(bdata, addr, size); >> >> > >> + unsigned long pos = addr; >> >> > >> + unsigned long partsize = size; >> >> > >> + >> >> > >> + list_for_each_entry(bdata, &bdata_list, list) { >> >> > >> + unsigned long remainder = 0; >> >> > >> + >> >> > >> + if (pos < bdata->node_boot_start) >> >> > >> + continue; >> >> > >> + >> >> > >> + if (PFN_DOWN(pos + partsize) > bdata->node_low_pfn) { >> >> > >> + remainder = PFN_DOWN(pos + partsize) - bdata->node_low_pfn; >> >> > >> + partsize -= remainder; >> >> > >> + } >> >> > >> + >> >> > >> + free_bootmem_core(bdata, pos, partsize); >> >> > >> + >> >> > >> + if (!remainder) >> >> > >> + return; >> >> > >> + >> >> > >> + pos = PFN_PHYS(bdata->node_low_pfn + 1); >> >> > >> + } >> >> > >> + printk(KERN_ERR "free_bootmem: request: addr=%lx, size=%lx, " >> >> > >> + "state: pos=%lx, partsize=%lx\n", addr, size, >> >> > >> + pos, partsize); >> >> > >> + BUG(); >> >> > >> } >> >> > >> >> >> > >> unsigned long __init free_all_bootmem(void) >> >> > >> >> >> > > >> >> > > it will not work with cross nodes. >> >> > > >> >> > > for example: node 0: 0-2g, 4-6g, node1: 2-4g, 6-8g. >> >> > > and if ramdisk sit cross 2G boundary. you will only free the range >> >> > > before 2g. >> >> > >> >> > Yes, you stated that several times but this is not a technical argument: >> >> > These setups are afaik not yet supported by the kernel at all. And you >> >> > could not explain the node layout with the patch that implements support >> >> > for these configurations. >> >> >> >> I looked at Suresh's patch, and it still only has one bdata for one node. >> > >> > Suresh's patch already in the Linus tree. >> > commit 6ec6e0d9f2fd7cb6ca6bc3bfab5ae7b5cdd8c36f >> > Author: Suresh Siddha <suresh.b.siddha@intel.com> >> > Date: Tue Mar 25 10:14:35 2008 -0700 >> > >> > srat, x86: add support for nodes spanning other nodes >> > >> > For example, If the physical address layout on a two node system with 8 GB >> > memory is something like: >> > node 0: 0-2GB, 4-6GB >> > node 1: 2-4GB, 6-8GB >> > >> > Current kernels fail to boot/detect this NUMA topology. >> > >> > ACPI SRAT tables can expose such a topology which needs to be supported. >> > >> > Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com> >> > Signed-off-by: Ingo Molnar <mingo@elte.hu> >> > Signed-off-by: Thomas Gleixner <tglx@linutronix.de> >> >> Okay, so we have one bdata for node 0 and one for node 1. Does that mean >> that both have overlapping pfn ranges? >> >> [1 ||||| ] >> [2 ||||| ] >> >> Like this? How are the ||||| represented in the bootmem maps of each bdata? > > Yes.
Okay. So they share the same PFNs. Now imagine the following scenario:
node0: 0-2GB, 4-6GB node1: 2-4GB, 6-8GB
/* Marks the range on node0 and node1 */ free_bootmem(1.5G, 2G);
/* Frees all bootmem on both nodes */ free_all_bootmem_node(NODE_DATA(0)); free_all_bootmem_node(NODE_DATA(1));
Aren't the same page descriptors send to __free_bootmem_pages() twice?
Hannes
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