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    Subject[PATCH 4.4 13/21] x86/boot: Fix kdump, cleanup aborted E820_PRAM max_pfn manipulation
    Date
    4.4-stable review patch.  If anyone has any objections, please let me know.

    ------------------

    From: Dan Williams <dan.j.williams@intel.com>

    commit 917db484dc6a69969d317b3e57add4208a8d9d42 upstream.

    In commit:

    ec776ef6bbe1 ("x86/mm: Add support for the non-standard protected e820 type")

    Christoph references the original patch I wrote implementing pmem support.
    The intent of the 'max_pfn' changes in that commit were to enable persistent
    memory ranges to be covered by the struct page memmap by default.

    However, that approach was abandoned when Christoph ported the patches [1], and
    that functionality has since been replaced by devm_memremap_pages().

    In the meantime, this max_pfn manipulation is confusing kdump [2] that
    assumes that everything covered by the max_pfn is "System RAM". This
    results in kdump hanging or crashing.

    [1]: https://lists.01.org/pipermail/linux-nvdimm/2015-March/000348.html
    [2]: https://bugzilla.redhat.com/show_bug.cgi?id=1351098

    So fix it.

    Reported-by: Zhang Yi <yizhan@redhat.com>
    Reported-by: Jeff Moyer <jmoyer@redhat.com>
    Tested-by: Zhang Yi <yizhan@redhat.com>
    Signed-off-by: Dan Williams <dan.j.williams@intel.com>
    Reviewed-by: Jeff Moyer <jmoyer@redhat.com>
    Cc: Andrew Morton <akpm@linux-foundation.org>
    Cc: Boaz Harrosh <boaz@plexistor.com>
    Cc: Christoph Hellwig <hch@lst.de>
    Cc: Linus Torvalds <torvalds@linux-foundation.org>
    Cc: Peter Zijlstra <peterz@infradead.org>
    Cc: Ross Zwisler <ross.zwisler@linux.intel.com>
    Cc: Thomas Gleixner <tglx@linutronix.de>
    Cc: linux-nvdimm@lists.01.org
    Fixes: ec776ef6bbe1 ("x86/mm: Add support for the non-standard protected e820 type")
    Link: http://lkml.kernel.org/r/147448744538.34910.11287693517367139607.stgit@dwillia2-desk3.amr.corp.intel.com
    Signed-off-by: Ingo Molnar <mingo@kernel.org>
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

    ---
    arch/x86/kernel/e820.c | 14 +++++---------
    1 file changed, 5 insertions(+), 9 deletions(-)

    --- a/arch/x86/kernel/e820.c
    +++ b/arch/x86/kernel/e820.c
    @@ -347,7 +347,7 @@ int __init sanitize_e820_map(struct e820
    * continue building up new bios map based on this
    * information
    */
    - if (current_type != last_type || current_type == E820_PRAM) {
    + if (current_type != last_type) {
    if (last_type != 0) {
    new_bios[new_bios_entry].size =
    change_point[chgidx]->addr - last_addr;
    @@ -753,7 +753,7 @@ u64 __init early_reserve_e820(u64 size,
    /*
    * Find the highest page frame number we have available
    */
    -static unsigned long __init e820_end_pfn(unsigned long limit_pfn)
    +static unsigned long __init e820_end_pfn(unsigned long limit_pfn, unsigned type)
    {
    int i;
    unsigned long last_pfn = 0;
    @@ -764,11 +764,7 @@ static unsigned long __init e820_end_pfn
    unsigned long start_pfn;
    unsigned long end_pfn;

    - /*
    - * Persistent memory is accounted as ram for purposes of
    - * establishing max_pfn and mem_map.
    - */
    - if (ei->type != E820_RAM && ei->type != E820_PRAM)
    + if (ei->type != type)
    continue;

    start_pfn = ei->addr >> PAGE_SHIFT;
    @@ -793,12 +789,12 @@ static unsigned long __init e820_end_pfn
    }
    unsigned long __init e820_end_of_ram_pfn(void)
    {
    - return e820_end_pfn(MAX_ARCH_PFN);
    + return e820_end_pfn(MAX_ARCH_PFN, E820_RAM);
    }

    unsigned long __init e820_end_of_low_ram_pfn(void)
    {
    - return e820_end_pfn(1UL << (32-PAGE_SHIFT));
    + return e820_end_pfn(1UL << (32 - PAGE_SHIFT), E820_RAM);
    }

    static void early_panic(char *msg)

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