• Toshi Kani's avatar
    x86/mm/pat: Change free_memtype() to support shrinking case · 2039e6ac
    Toshi Kani authored
    Using mremap() to shrink the map size of a VM_PFNMAP range causes
    the following error message, and leaves the pfn range allocated.
    
     x86/PAT: test:3493 freeing invalid memtype [mem 0x483200000-0x4863fffff]
    
    This is because rbt_memtype_erase(), called from free_memtype()
    with spin_lock held, only supports to free a whole memtype node in
    memtype_rbroot.  Therefore, this patch changes rbt_memtype_erase()
    to support a request that shrinks the size of a memtype node for
    mremap().
    
    memtype_rb_exact_match() is renamed to memtype_rb_match(), and
    is enhanced to support EXACT_MATCH and END_MATCH in @match_type.
    Since the memtype_rbroot tree allows overlapping ranges,
    rbt_memtype_erase() checks with EXACT_MATCH first, i.e. free
    a whole node for the munmap case.  If no such entry is found,
    it then checks with END_MATCH, i.e. shrink the size of a node
    from the end for the mremap case.
    
    On the mremap case, rbt_memtype_erase() proceeds in two steps,
    1) remove the node, and then 2) insert the updated node.  This
    allows proper update of augmented values, subtree_max_end, in
    the tree.
    Signed-off-by: default avatarToshi Kani <toshi.kani@hpe.com>
    Cc: Ingo Molnar <mingo@redhat.com>
    Cc: H. Peter Anvin <hpa@zytor.com>
    Cc: Borislav Petkov <bp@suse.de>
    Cc: stsp@list.ru
    Cc: linux-mm@kvack.org
    Link: http://lkml.kernel.org/r/1450832064-10093-3-git-send-email-toshi.kani@hpe.comSigned-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
    2039e6ac
pat.c 27.5 KB