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    SubjectRe: [PATCH v2] MIPS: Kernel crashes on boot with SPARSEMEM + HIGHMEM enabled
    On 03/31/2011 05:27 PM, Kevin Cernekee wrote:
    > From: Michael Sundius<msundius@cisco.com>
    >
    > Fix 3 problems in the MIPS SPARSEMEM implementation:
    >
    > 1) mem_init() sets/clears PG_reserved on all pages in the HIGHMEM range
    > without checking to see whether the page descriptor actually exists.
    >
    > 2) bootmem_init() never calls memory_present() on HIGHMEM pages, so
    > page descriptors are never created for them if SPARSEMEM is enabled.
    >
    > 3) bootmem_init() calls memory_present() on lowmem pages before bootmem
    > is fully set up. This is bad because memory_present() can allocate
    > bootmem in some circumstances (e.g. if SPARSEMEM_EXTREME ever got
    > enabled).
    >


    I think this may do the same thing as my patch:

    http://patchwork.linux-mips.org/patch/1988/

    Although my patch had different motivations, and changes some other
    things around too.

    David Daney


    > Signed-off-by: Michael Sundius<msundius@cisco.com>
    > Signed-off-by: Kevin Cernekee<cernekee@gmail.com>
    > Cc: stable@kernel.org
    > ---
    > arch/mips/kernel/setup.c | 18 +++++++++++++++++-
    > arch/mips/mm/init.c | 3 +++
    > 2 files changed, 20 insertions(+), 1 deletions(-)
    >
    > diff --git a/arch/mips/kernel/setup.c b/arch/mips/kernel/setup.c
    > index 8ad1d56..1f9f902 100644
    > --- a/arch/mips/kernel/setup.c
    > +++ b/arch/mips/kernel/setup.c
    > @@ -390,7 +390,6 @@ static void __init bootmem_init(void)
    >
    > /* Register lowmem ranges */
    > free_bootmem(PFN_PHYS(start), size<< PAGE_SHIFT);
    > - memory_present(0, start, end);
    > }
    >
    > /*
    > @@ -402,6 +401,23 @@ static void __init bootmem_init(void)
    > * Reserve initrd memory if needed.
    > */
    > finalize_initrd();
    > +
    > + /*
    > + * Call memory_present() on all valid ranges, for SPARSEMEM.
    > + * This must be done after setting up bootmem, since memory_present()
    > + * may allocate bootmem.
    > + */
    > + for (i = 0; i< boot_mem_map.nr_map; i++) {
    > + unsigned long start, end;
    > +
    > + if (boot_mem_map.map[i].type != BOOT_MEM_RAM)
    > + continue;
    > +
    > + start = PFN_UP(boot_mem_map.map[i].addr);
    > + end = PFN_DOWN(boot_mem_map.map[i].addr
    > + + boot_mem_map.map[i].size);
    > + memory_present(0, start, end);
    > + }
    > }
    >
    > #endif /* CONFIG_SGI_IP27 */
    > diff --git a/arch/mips/mm/init.c b/arch/mips/mm/init.c
    > index 279599e..78a4cf2 100644
    > --- a/arch/mips/mm/init.c
    > +++ b/arch/mips/mm/init.c
    > @@ -392,6 +392,9 @@ void __init mem_init(void)
    > for (tmp = highstart_pfn; tmp< highend_pfn; tmp++) {
    > struct page *page = pfn_to_page(tmp);
    >
    > + if (!pfn_valid(tmp))
    > + continue;
    > +
    > if (!page_is_ram(tmp)) {
    > SetPageReserved(page);
    > continue;



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