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SubjectRe: [RFC][patch 2/5] mm: Node-setup agnostic free_bootmem()
On Wed, Apr 16, 2008 at 10:54 AM, Yinghai Lu <yhlu.kernel@gmail.com> wrote:
>
> On Wed, Apr 16, 2008 at 4:36 AM, Johannes Weiner <hannes@saeurebad.de> wrote:
> > 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: Ingo Molnar <mingo@elte.hu>
> > 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>
> > ---
> > mm/bootmem.c | 10 +++++++++-
> > 1 files changed, 9 insertions(+), 1 deletions(-)
> >
> > Index: tree-linus/mm/bootmem.c
> > ===================================================================
> > --- tree-linus.orig/mm/bootmem.c
> > +++ tree-linus/mm/bootmem.c
> > @@ -421,7 +421,32 @@ int __init reserve_bootmem(unsigned long
> >
> > void __init free_bootmem(unsigned long addr, unsigned long size)
> > {
> > - free_bootmem_core(NODE_DATA(0)->bdata, addr, size);
> > + bootmem_data_t *bdata;
> > + 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)
> >
> > --
>
> Yes, it should work well with cross nodes case.
>
> but please add boundary check on free_bootmem_node too.

also please note:
it will have problem span nodes box.

for example: node 0: 0-2g, 4-6g, node1: 2-4g, 6-8g.
and if ramdisk sit creoss 2G boundary. you will only free the range before 2g.

YH


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