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SubjectRe: [Lhms-devel] [PATCH] memory hotadd fixes [4/5] avoid check in acpi
Hi, Keith

Thank you for test.

On Thu, 03 Aug 2006 16:09:36 -0700
keith mannthey <kmannth@us.ibm.com> wrote:
> > > drivers/acpi/acpi_memhotplug.c | 9 +--------
> > > 1 files changed, 1 insertion(+), 8 deletions(-)
> > >
> > > Index: linux-2.6.18-rc3/drivers/acpi/acpi_memhotplug.c
> > > ===================================================================
> > > --- linux-2.6.18-rc3.orig/drivers/acpi/acpi_memhotplug.c 2006-08-01 16:11:47.000000000 +0900
> > > +++ linux-2.6.18-rc3/drivers/acpi/acpi_memhotplug.c 2006-08-02 14:12:45.000000000 +0900
> > > @@ -230,17 +230,10 @@
> > > * (i.e. memory-hot-remove function)
> > > */
> > > list_for_each_entry(info, &mem_device->res_list, list) {
> > > - u64 start_pfn, end_pfn;
> > > -
> > > - start_pfn = info->start_addr >> PAGE_SHIFT;
> > > - end_pfn = (info->start_addr + info->length - 1) >> PAGE_SHIFT;
> > > -
> > > - if (pfn_valid(start_pfn) || pfn_valid(end_pfn)) {
> > > - /* already enabled. try next area */
> > > + if (info->enabled) { /* just sanity check...*/
> > > num_enabled++;
> > > continue;
> > > }
> >
> > This check needs to go. pfn_valid is a sparsemem specific check. Sanity
> > checking should be done it the the add_memory code.
> >
> > I will test and let you know. This is going to expose some baddness I
> > see already with my RESERVE path work. (Extra add_memory calls from this
> > driver during boot....)
>
> Ok. This pfn_valid check needs to be inserted somewhere in the code
> path for sparsemem hotadd.
>
> with a debug statement in add_memory
>
> Hotplug Mem Device
> add_memory 0 400000000 70000000
> System RAM resource 400000000 - 46fffffff cannot be added

This messages is at ioresouce collision check. This says system has
memory resource between 400000000 - 46fffffff...before hotadd.
and sparse_add_one_seciton() returns -EEXIST if section exists.
==
int sparse_add_one_section(struct zone *zone, unsigned long start_pfn,
int nr_pages)
{
<snip>
if (ms->section_mem_map & SECTION_MARKED_PRESENT) {
ret = -EEXIST;
goto out;
}
}
==
Ah... but x86_64 special (not depends on sparsemem..) __add_pages() call doesn't
do sanity check at online_page().
Here.
==
for (pfn = start_pfn; pfn < start_pfn + nr_pages; pfn++) {
if (pfn_valid(pfn)) {
online_page(pfn_to_page(pfn));
err = 0;
mem++;
}
==
So, panics ...maybe.
(System has memory between 40000000 - 46fffffff but it's onlined again)
Could you add sanity check in online_page() ?
==
if (PageReserved(page) {
online_page(pfn_to_page(pfn));
}
==
will be enough.
I don't have avaliable x86_64 box now.

-Kame

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