Messages in this thread | | | Subject | Re: [PATCH] memory hotadd fixes [4/5] avoid check in acpi | From | keith mannthey <> | Date | Thu, 03 Aug 2006 20:23:46 -0700 |
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On Fri, 2006-08-04 at 12:13 +0900, KAMEZAWA Hiroyuki wrote: > On Thu, 03 Aug 2006 20:00:08 -0700 > keith mannthey <kmannth@us.ibm.com> wrote: > > > > > > What protecting is there for calling add_memory on an already present > > > > memory range? > > > > > > > For example, considering ia64, which has 1Gbytes section... > > > > Maybe 1gb sections is too large? > > > ia64 machines sometimes to have crazy big memory...so 1gb section is requested. > Configurable section_size for small machines was rejected in old days.
My HW supports about 512gb......
What if you add a partial section. Then online in sysfs and add another section? messy.... > > > > hot add following region. > > > == > > > (A) 0xc0000000 - 0xd7ffffff (section 3) > > > (B) 0xe0000000 - 0xffffffff (section 3) > > > == > > > (A) and (B) will go to the same section, but there is a memory hole between > > > (A) and (B). Considering memory (B) appears after (A) in DSDT. > > > > > > After add_memory() against (A) is called, section 3 is ready. > > > Then, pfn_valid(0xe0000000) and pfn_valid(0xffffffff) returns true because > > > they are in section 3. > > > So, checking pfn_valid() for (B) will returns true and memory (B) cannot be > > > added. ioresouce collision check will help this situation. > > > > With iommus out there throwing aliment all off way the flexability is > > good. > > > > My question is this. > > > > Assuming 0-0xbfffffff is present. > > > > What keeps 0xa0000000 to 0xa1000000 from being re-onlined by a bad call > > to add_memory? > > Usual sparsemem's add_memory() checks whether there are sections in > sparse_add_one_section(). then add_pages() returns -EEXIST (nothing to do). > And ioresouce collision check will finally find collision because 0-0xbffffff > resource will conflict with 0xa0000000 to 0xa10000000 area. > But, x86_64 's (not sparsemem) add_pages() doen't do collision check, so it panics.
I have paniced with your 5 patches while doing SPARSMEM.... I think your 6th patch address the issues I was seeing.
Thanks, Keith
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