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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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