queue-4.14/revert-mm-use-early_pfn_to_nid-in-page_ext_init.patch

   1 From bc0c88889784544219b105d48b313218514965d9 Mon Sep 17 00:00:00 2001
   2 From: Qian Cai <cai@lca.pw>
   3 Date: Tue, 12 Feb 2019 15:36:03 -0800
   4 Subject: Revert "mm: use early_pfn_to_nid in page_ext_init"
   5
   6 [ Upstream commit 2f1ee0913ce58efe7f18fbd518bd54c598559b89 ]
   7
   8 This reverts commit fe53ca54270a ("mm: use early_pfn_to_nid in
   9 page_ext_init").
  10
  11 When booting a system with "page_owner=on",
  12
  13 start_kernel
  14   page_ext_init
  15     invoke_init_callbacks
  16       init_section_page_ext
  17         init_page_owner
  18           init_early_allocated_pages
  19             init_zones_in_node
  20               init_pages_in_zone
  21                 lookup_page_ext
  22                   page_to_nid
  23
  24 The issue here is that page_to_nid() will not work since some page flags
  25 have no node information until later in page_alloc_init_late() due to
  26 DEFERRED_STRUCT_PAGE_INIT.  Hence, it could trigger an out-of-bounds
  27 access with an invalid nid.
  28
  29   UBSAN: Undefined behaviour in ./include/linux/mm.h:1104:50
  30   index 7 is out of range for type 'zone [5]'
  31
  32 Also, kernel will panic since flags were poisoned earlier with,
  33
  34 CONFIG_DEBUG_VM_PGFLAGS=y
  35 CONFIG_NODE_NOT_IN_PAGE_FLAGS=n
  36
  37 start_kernel
  38   setup_arch
  39     pagetable_init
  40       paging_init
  41         sparse_init
  42           sparse_init_nid
  43             memblock_alloc_try_nid_raw
  44
  45 It did not handle it well in init_pages_in_zone() which ends up calling
  46 page_to_nid().
  47
  48   page:ffffea0004200000 is uninitialized and poisoned
  49   raw: ffffffffffffffff ffffffffffffffff ffffffffffffffff ffffffffffffffff
  50   raw: ffffffffffffffff ffffffffffffffff ffffffffffffffff ffffffffffffffff
  51   page dumped because: VM_BUG_ON_PAGE(PagePoisoned(p))
  52   page_owner info is not active (free page?)
  53   kernel BUG at include/linux/mm.h:990!
  54   RIP: 0010:init_page_owner+0x486/0x520
  55
  56 This means that assumptions behind commit fe53ca54270a ("mm: use
  57 early_pfn_to_nid in page_ext_init") are incomplete.  Therefore, revert
  58 the commit for now.  A proper way to move the page_owner initialization
  59 to sooner is to hook into memmap initialization.
  60
  61 Link: http://lkml.kernel.org/r/20190115202812.75820-1-cai@lca.pw
  62 Signed-off-by: Qian Cai <cai@lca.pw>
  63 Acked-by: Michal Hocko <mhocko@kernel.org>
  64 Cc: Pasha Tatashin <Pavel.Tatashin@microsoft.com>
  65 Cc: Mel Gorman <mgorman@techsingularity.net>
  66 Cc: Yang Shi <yang.shi@linaro.org>
  67 Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
  68 Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
  69 Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
  70 Signed-off-by: Sasha Levin <sashal@kernel.org>
  71 ---
  72  init/main.c   | 3 ++-
  73  mm/page_ext.c | 4 +---
  74  2 files changed, 3 insertions(+), 4 deletions(-)
  75
  76 diff --git a/init/main.c b/init/main.c
  77 index c4a45145e102..3d3d79c5a232 100644
  78 --- a/init/main.c
  79 +++ b/init/main.c
  80 @@ -663,7 +663,6 @@ asmlinkage __visible void __init start_kernel(void)
  81                 initrd_start = 0;
  82         }
  83  #endif
  84 -       page_ext_init();
  85         kmemleak_init();
  86         debug_objects_mem_init();
  87         setup_per_cpu_pageset();
  88 @@ -1069,6 +1068,8 @@ static noinline void __init kernel_init_freeable(void)
  89         sched_init_smp();
  90
  91         page_alloc_init_late();
  92 +       /* Initialize page ext after all struct pages are initialized. */
  93 +       page_ext_init();
  94
  95         do_basic_setup();
  96
  97 diff --git a/mm/page_ext.c b/mm/page_ext.c
  98 index 2c16216c29b6..2c44f5b78435 100644
  99 --- a/mm/page_ext.c
 100 +++ b/mm/page_ext.c
 101 @@ -396,10 +396,8 @@ void __init page_ext_init(void)
 102                          * We know some arch can have a nodes layout such as
 103                          * -------------pfn-------------->
 104                          * N0 | N1 | N2 | N0 | N1 | N2|....
 105 -                        *
 106 -                        * Take into account DEFERRED_STRUCT_PAGE_INIT.
 107                          */
 108 -                       if (early_pfn_to_nid(pfn) != nid)
 109 +                       if (pfn_to_nid(pfn) != nid)
 110                                 continue;
 111                         if (init_section_page_ext(pfn, nid))
 112                                 goto oom;
 113 --
 114 2.19.1
 115