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Message-ID: <86802c440804301330y641a5baq8232502b67147d6b@mail.gmail.com>
Date: Wed, 30 Apr 2008 13:30:27 -0700
From: "Yinghai Lu" <yhlu.kernel@...il.com>
To: "Johannes Weiner" <hannes@...urebad.de>
Cc: "Ingo Molnar" <mingo@...e.hu>,
"Linus Torvalds" <torvalds@...ux-foundation.org>,
linux-kernel@...r.kernel.org,
"Andrew Morton" <akpm@...ux-foundation.org>,
"Thomas Gleixner" <tglx@...utronix.de>,
"H. Peter Anvin" <hpa@...or.com>, jbarnes@...tuousgeek.org,
"Siddha, Suresh B" <suresh.b.siddha@...el.com>
Subject: Re: [patch] mm: node-setup agnostic free_bootmem()
On Wed, Apr 30, 2008 at 10:52 AM, Johannes Weiner <hannes@...urebad.de> wrote:
>
> Hi,
>
> "Yinghai Lu" <yhlu.kernel@...il.com> writes:
>
> > On Wed, Apr 30, 2008 at 3:50 AM, Johannes Weiner <hannes@...urebad.de> wrote:
> >>
> >> Hi,
> >>
> >> "Yinghai Lu" <yhlu.kernel@...il.com> writes:
> >>
> >> > On Mon, Apr 28, 2008 at 12:11 PM, Yinghai Lu <yhlu.kernel@...il.com> wrote:
> >> >>
> >> >> On Mon, Apr 28, 2008 at 9:54 AM, Johannes Weiner <hannes@...urebad.de> wrote:
> >> >> > Hi Yinghai,
> >> >> >
> >> >> >
> >> >> >
> >> >> > "Yinghai Lu" <yhlu.kernel@...il.com> writes:
> >> >> >
> >> >> > > On Sun, Apr 27, 2008 at 5:40 PM, Ingo Molnar <mingo@...e.hu> wrote:
> >> >> > >>
> >> >> > >> * Johannes Weiner <hannes@...urebad.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@...urebad.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@...urebad.de>
> >> >> > >> CC: Andi Kleen <andi@...stfloor.org>
> >> >> > >> CC: Yinghai Lu <yhlu.kernel@...il.com>
> >> >> > >> CC: Yasunori Goto <y-goto@...fujitsu.com>
> >> >> > >> CC: KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>
> >> >> > >> CC: Christoph Lameter <clameter@....com>
> >> >> > >> CC: Andrew Morton <akpm@...ux-foundation.org>
> >> >> > >> Signed-off-by: Ingo Molnar <mingo@...e.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@...el.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@...el.com>
> >> > Signed-off-by: Ingo Molnar <mingo@...e.hu>
> >> > Signed-off-by: Thomas Gleixner <tglx@...utronix.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?
yeah, there is some problem....
may need to ask every node took another node_bootmem_not_use_map ...to
record the holes.
YH
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