• Yinghai Lu's avatar
    memblock: free allocated memblock_reserved_regions later · 29f67386
    Yinghai Lu authored
    memblock_free_reserved_regions() calls memblock_free(), but
    memblock_free() would double reserved.regions too, so we could free the
    old range for reserved.regions.
    
    Also tj said there is another bug which could be related to this.
    
    | I don't think we're saving any noticeable
    | amount by doing this "free - give it to page allocator - reserve
    | again" dancing.  We should just allocate regions aligned to page
    | boundaries and free them later when memblock is no longer in use.
    
    in that case, when DEBUG_PAGEALLOC, will get panic:
    
         memblock_free: [0x0000102febc080-0x0000102febf080] memblock_free_reserved_regions+0x37/0x39
      BUG: unable to handle kernel paging request at ffff88102febd948
      IP: [<ffffffff836a5774>] __next_free_mem_range+0x9b/0x155
      PGD 4826063 PUD cf67a067 PMD cf7fa067 PTE 800000102febd160
      Oops: 0000 [#1] PREEMPT SMP DEBUG_PAGEALLOC
      CPU 0
      Pid: 0, comm: swapper Not tainted 3.5.0-rc2-next-20120614-sasha #447
      RIP: 0010:[<ffffffff836a5774>]  [<ffffffff836a5774>] __next_free_mem_range+0x9b/0x155
    
    See the discussion at https://lkml.org/lkml/2012/6/13/469
    
    So try to allocate with PAGE_SIZE alignment and free it later.
    Reported-by: Sasha Levin's avatarSasha Levin <levinsasha928@gmail.com>
    Acked-by: default avatarTejun Heo <tj@kernel.org>
    Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
    Signed-off-by: default avatarYinghai Lu <yinghai@kernel.org>
    Cc: <stable@vger.kernel.org>
    Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
    Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
    29f67386
memblock.h 7.97 KB