Re: [Lhms-devel] [PATCH] memory hotadd fixes [4/5] avoid check inacpi

From: keith mannthey
Date: Thu Aug 03 2006 - 19:07:23 EST


On Thu, 2006-08-03 at 11:28 -0700, keith mannthey wrote:
> On Thu, 2006-08-03 at 12:36 +0900, KAMEZAWA Hiroyuki wrote:
> > add_memory() does all necessary check to avoid collision.
> > then, acpi layer doesn't have to check region by itself.
> >
> > (*) pfn_valid() just returns page struct is valid or not. It returns 0
> > if a section has been already added even is ioresource is not added.
> > ioresource collision check in mm/memory_hotplug.c can do more precise
> > collistion check.
> > added enabled bit check just for sanity check..
> >
> > Signed-Off-By: KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx>
> >
> >
> > 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
add_memory 0 380000000 80000000
System RAM resource 380000000 - 3ffffffff cannot be added
add_memory 0 300000000 80000000
System RAM resource 300000000 - 37fffffff cannot be added
add_memory 0 280000000 80000000
System RAM resource 280000000 - 2ffffffff cannot be added
add_memory 0 200000000 80000000
System RAM resource 200000000 - 27fffffff cannot be added
add_memory 0 180000000 80000000
System RAM resource 180000000 - 1ffffffff cannot be added
add_memory 0 100000000 80000000
System RAM resource 100000000 - 17fffffff cannot be added
add_memory 0 100000 7ff00000

The box doesn't boot. I am going to drop this patch and see about the
rest of the set. (They seem sane and look ok but I want to test)

The kernel needs to protect against bad calls to add_memory (and/or the
acpi driver needs to correctly id devices?)


keith mannthey <kmannth@xxxxxxxxxx>
Linux Technology Center IBM

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