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    SubjectRe: [PATCH] mm/memblock: fix overlapping allocation when doubling reserved array
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    On Fri, Jun 15, 2012 at 2:09 PM, Greg Pearson <greg.pearson@hp.com> wrote:
    > The __alloc_memory_core_early() routine will ask memblock for a range
    > of memory then try to reserve it. If the reserved region array lacks
    > space for the new range, memblock_double_array() is called to allocate
    > more space for the array. If memblock is used to allocate memory for
    > the new array it can end up using a range that overlaps with the range
    > originally allocated in __alloc_memory_core_early(), leading to possible
    > data corruption.
    >
    > With this patch memblock_double_array() now calls memblock_find_in_range()
    > with a narrowed candidate range so any memory allocated will not overlap
    > with the original range that was being reserved. The range is narrowed by
    > passing in the starting address of the previously allocated range as the
    > end of the candidate range. Since memblock_find_in_range_node() looks for
    > a free range by walking the free memory list in reverse order (highest
    > memory address to lowest address) this change should not unnecessarily
    > exclude chunks of memory that could otherwise be used to satisfy the
    > request.

    old early_res version have exclude_start/exclude_end.

    >
    > Signed-off-by: Greg Pearson <greg.pearson@hp.com>
    > ---
    >  mm/memblock.c |   11 +++++++----
    >  1 files changed, 7 insertions(+), 4 deletions(-)
    >
    > diff --git a/mm/memblock.c b/mm/memblock.c
    > index 952123e..599519c 100644
    > --- a/mm/memblock.c
    > +++ b/mm/memblock.c
    > @@ -184,7 +184,8 @@ static void __init_memblock memblock_remove_region(struct memblock_type *type, u
    >        }
    >  }
    >
    > -static int __init_memblock memblock_double_array(struct memblock_type *type)
    > +static int __init_memblock memblock_double_array(struct memblock_type *type,
    > +                                               phys_addr_t skip_base)

    could pass phys_addr_t exclude_base, phys_addr_t execlude_end

    >  {
    >        struct memblock_region *new_array, *old_array;
    >        phys_addr_t old_size, new_size, addr;
    > @@ -222,7 +223,8 @@ static int __init_memblock memblock_double_array(struct memblock_type *type)
    >                new_array = kmalloc(new_size, GFP_KERNEL);
    >                addr = new_array ? __pa(new_array) : 0;
    >        } else {
    > -               addr = memblock_find_in_range(0, MEMBLOCK_ALLOC_ACCESSIBLE, new_size, sizeof(phys_addr_t));
    > +               addr = memblock_find_in_range(0, skip_base,
    > +                               new_size, sizeof(phys_addr_t));

    could try to search [exclude_end, MEMBLOCK_ALLOC_ACCESSIBLE) at first.
    then try [0, execlude_start).

    Yinghai
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