1. 18 Sep, 2009 38 commits
  2. 17 Sep, 2009 2 commits
    • H. Peter Anvin's avatar
      Merge branch 'x86/pat' into x86/urgent · 3bb045f1
      H. Peter Anvin authored
      Merge reason:
      
      Suresh Siddha (1):
            x86, pat: don't use rb-tree based lookup in reserve_memtype()
      
      ... requires previous x86/pat commits already pushed to Linus.
      Signed-off-by: default avatarH. Peter Anvin <hpa@zytor.com>
      3bb045f1
    • Suresh Siddha's avatar
      x86, pat: don't use rb-tree based lookup in reserve_memtype() · dcb73bf4
      Suresh Siddha authored
      Recent enhancement of rb-tree based lookup exposed a  bug with the lookup
      mechanism in the reserve_memtype() which ensures that there are no conflicting
      memtype requests for the memory range.
      
      memtype_rb_search() returns an entry which has a start address <= new start
      address. And from here we traverse the linear linked list to check if there
      any conflicts with the existing mappings. As the rbtree is based on the
      start address of the memory range, it is quite possible that we have several
      overlapped mappings whose start address is much less than new requested start
      but the end is >= new requested end. This results in conflicting memtype
      mappings.
      
      Same bug exists with the old code which uses cached_entry from where
      we traverse the linear linked list. But the new rb-tree code exposes this
      bug fairly easily.
      
      For now, don't use the memtype_rb_search() and always start the search from
      the head of linear linked list in reserve_memtype(). Linear linked list
      for most of the systems grow's to few 10's of entries(as we track memory type
      of RAM pages using struct page). So we should be ok for now.
      
      We still retain the rbtree and use it to speed up free_memtype() which
      doesn't have the same bug(as we know what exactly we are searching for
      in free_memtype).
      
      Also use list_for_each_entry_from() in free_memtype() so that we start
      the search from rb-tree lookup result.
      Reported-by: default avatarMarkus Trippelsdorf <markus@trippelsdorf.de>
      Signed-off-by: default avatarSuresh Siddha <suresh.b.siddha@intel.com>
      Cc: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
      LKML-Reference: <1253136483.4119.12.camel@sbs-t61.sc.intel.com>
      Signed-off-by: default avatarH. Peter Anvin <hpa@zytor.com>
      dcb73bf4