1. 20 Mar, 2007 1 commit
    • Zou Nan hai's avatar
      [IA64] min_low_pfn and max_low_pfn calculation fix · a3f5c338
      Zou Nan hai authored
      We have seen bad_pte_print when testing crashdump on an SN machine in
      recent 2.6.20 kernel.  There are tons of bad pte print (pfn < max_low_pfn)
      reports when the crash kernel boots up, all those reported bad pages
      are inside initmem range; That is because if the crash kernel code and
      data happens to be at the beginning of the 1st node. build_node_maps in
      discontig.c will bypass reserved regions with filter_rsvd_memory. Since
      min_low_pfn is calculated in build_node_map, so in this case, min_low_pfn
      will be greater than kernel code and data.
      
      Because pages inside initmem are freed and reused later, we saw
      pfn_valid check fail on those pages.
      
      I think this theoretically happen on a normal kernel. When I check
      min_low_pfn and max_low_pfn calculation in contig.c and discontig.c.
      I found more issues than this.
      
      1. min_low_pfn and max_low_pfn calculation is inconsistent between
      contig.c and discontig.c,
      min_low_pfn is calculated as the first page number of boot memmap in
      contig.c (Why? Though this may work at the most of the time, I don't
      think it is the right logic). It is calculated as the lowest physical
      memory page number bypass reserved regions in discontig.c.
      max_low_pfn is calculated include reserved regions in contig.c. It is
      calculated exclude reserved regions in discontig.c.
      
      2. If kernel code and data region is happen to be at the begin or the
      end of physical memory, when min_low_pfn and max_low_pfn calculation is
      bypassed kernel code and data, pages in initmem will report bad.
      
      3. initrd is also in reserved regions, if it is at the begin or at the
      end of physical memory, kernel will refuse to reuse the memory. Because
      the virt_addr_valid check in free_initrd_mem.
      
      So it is better to fix and clean up those issues.
      Calculate min_low_pfn and max_low_pfn in a consistent way.
      Signed-off-by: default avatarZou Nan hai <nanhai.zou@intel.com>
      Acked-by: default avatarJay Lan <jlan@sgi.com>
      Signed-off-by: default avatarTony Luck <tony.luck@intel.com>
      a3f5c338
  2. 10 Mar, 2007 39 commits