• Michal Hocko's avatar
    mm: Ensure that pfn_valid() is called once per pageblock when reserving pageblocks · d0215638
    Michal Hocko authored
    setup_zone_migrate_reserve() expects that zone->start_pfn starts at
    pageblock_nr_pages aligned pfn otherwise we could access beyond an
    existing memblock resulting in the following panic if
    CONFIG_HOLES_IN_ZONE is not configured and we do not check pfn_valid:
    
      IP: [<c02d331d>] setup_zone_migrate_reserve+0xcd/0x180
      *pdpt = 0000000000000000 *pde = f000ff53f000ff53
      Oops: 0000 [#1] SMP
      Pid: 1, comm: swapper Not tainted 3.0.7-0.7-pae #1 VMware, Inc. VMware Virtual Platform/440BX Desktop Reference Platform
      EIP: 0060:[<c02d331d>] EFLAGS: 00010006 CPU: 0
      EIP is at setup_zone_migrate_reserve+0xcd/0x180
      EAX: 000c0000 EBX: f5801fc0 ECX: 000c0000 EDX: 00000000
      ESI: 000c01fe EDI: 000c01fe EBP: 00140000 ESP: f2475f58
      DS: 007b ES: 007b FS: 00d8 GS: 0000 SS: 0068
      Process swapper (pid: 1, ti=f2474000 task=f2472cd0 task.ti=f2474000)
      Call Trace:
      [<c02d389c>] __setup_per_zone_wmarks+0xec/0x160
      [<c02d3a1f>] setup_per_zone_wmarks+0xf/0x20
      [<c08a771c>] init_per_zone_wmark_min+0x27/0x86
      [<c020111b>] do_one_initcall+0x2b/0x160
      [<c086639d>] kernel_init+0xbe/0x157
      [<c05cae26>] kernel_thread_helper+0x6/0xd
      Code: a5 39 f5 89 f7 0f 46 fd 39 cf 76 40 8b 03 f6 c4 08 74 32 eb 91 90 89 c8 c1 e8 0e 0f be 80 80 2f 86 c0 8b 14 85 60 2f 86 c0 89 c8 <2b> 82 b4 12 00 00 c1 e0 05 03 82 ac 12 00 00 8b 00 f6 c4 08 0f
      EIP: [<c02d331d>] setup_zone_migrate_reserve+0xcd/0x180 SS:ESP 0068:f2475f58
      CR2: 00000000000012b4
    
    We crashed in pageblock_is_reserved() when accessing pfn 0xc0000 because
    highstart_pfn = 0x36ffe.
    
    The issue was introduced in 3.0-rc1 by 6d3163ce ("mm: check if any page
    in a pageblock is reserved before marking it MIGRATE_RESERVE").
    
    Make sure that start_pfn is always aligned to pageblock_nr_pages to
    ensure that pfn_valid s always called at the start of each pageblock.
    Architectures with holes in pageblocks will be correctly handled by
    pfn_valid_within in pageblock_is_reserved.
    Signed-off-by: default avatarMichal Hocko <mhocko@suse.cz>
    Signed-off-by: default avatarMel Gorman <mgorman@suse.de>
    Tested-by: default avatarDang Bo <bdang@vmware.com>
    Reviewed-by: default avatarKAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
    Cc: Andrea Arcangeli <aarcange@redhat.com>
    Cc: David Rientjes <rientjes@google.com>
    Cc: Arve Hjnnevg <arve@android.com>
    Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
    Cc: John Stultz <john.stultz@linaro.org>
    Cc: Dave Hansen <dave@linux.vnet.ibm.com>
    Cc: <stable@vger.kernel.org>	[3.0+]
    Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
    Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
    d0215638
page_alloc.c 160 KB