• Daniel Vacek's avatar
    Revert "mm: page_alloc: skip over regions of invalid pfns where possible" · f59f1caf
    Daniel Vacek authored
    This reverts commit b92df1de ("mm: page_alloc: skip over regions of
    invalid pfns where possible").  The commit is meant to be a boot init
    speed up skipping the loop in memmap_init_zone() for invalid pfns.
    
    But given some specific memory mapping on x86_64 (or more generally
    theoretically anywhere but on arm with CONFIG_HAVE_ARCH_PFN_VALID) the
    implementation also skips valid pfns which is plain wrong and causes
    'kernel BUG at mm/page_alloc.c:1389!'
    
      crash> log | grep -e BUG -e RIP -e Call.Trace -e move_freepages_block -e rmqueue -e freelist -A1
      kernel BUG at mm/page_alloc.c:1389!
      invalid opcode: 0000 [#1] SMP
      --
      RIP: 0010: move_freepages+0x15e/0x160
      --
      Call Trace:
        move_freepages_block+0x73/0x80
        __rmqueue+0x263/0x460
        get_page_from_freelist+0x7e1/0x9e0
        __alloc_pages_nodemask+0x176/0x420
      --
    
      crash> page_init_bug -v | grep RAM
      <struct resource 0xffff88067fffd2f8>          1000 -        9bfff       System RAM (620.00 KiB)
      <struct resource 0xffff88067fffd3a0>        100000 -     430bffff       System RAM (  1.05 GiB = 1071.75 MiB = 1097472.00 KiB)
      <struct resource 0xffff88067fffd410>      4b0c8000 -     4bf9cfff       System RAM ( 14.83 MiB = 15188.00 KiB)
      <struct resource 0xffff88067fffd480>      4bfac000 -     646b1fff       System RAM (391.02 MiB = 400408.00 KiB)
      <struct resource 0xffff88067fffd560>      7b788000 -     7b7fffff       System RAM (480.00 KiB)
      <struct resource 0xffff88067fffd640>     100000000 -    67fffffff       System RAM ( 22.00 GiB)
    
      crash> page_init_bug | head -6
      <struct resource 0xffff88067fffd560>      7b788000 -     7b7fffff       System RAM (480.00 KiB)
      <struct page 0xffffea0001ede200>   1fffff00000000  0 <struct pglist_data 0xffff88047ffd9000> 1 <struct zone 0xffff88047ffd9800> DMA32          4096    1048575
      <struct page 0xffffea0001ede200>       505736 505344 <struct page 0xffffea0001ed8000> 505855 <struct page 0xffffea0001edffc0>
      <struct page 0xffffea0001ed8000>                0  0 <struct pglist_data 0xffff88047ffd9000> 0 <struct zone 0xffff88047ffd9000> DMA               1       4095
      <struct page 0xffffea0001edffc0>   1fffff00000400  0 <struct pglist_data 0xffff88047ffd9000> 1 <struct zone 0xffff88047ffd9800> DMA32          4096    1048575
      BUG, zones differ!
    
      crash> kmem -p 77fff000 78000000 7b5ff000 7b600000 7b787000 7b788000
            PAGE        PHYSICAL      MAPPING       INDEX CNT FLAGS
      ffffea0001e00000  78000000                0        0  0 0
      ffffea0001ed7fc0  7b5ff000                0        0  0 0
      ffffea0001ed8000  7b600000                0        0  0 0       <<<<
      ffffea0001ede1c0  7b787000                0        0  0 0
      ffffea0001ede200  7b788000                0        0  1 1fffff00000000
    
    Link: http://lkml.kernel.org/r/20180316143855.29838-1-neelx@redhat.com
    Fixes: b92df1de ("mm: page_alloc: skip over regions of invalid pfns where possible")
    Signed-off-by: default avatarDaniel Vacek <neelx@redhat.com>
    Acked-by: default avatarArd Biesheuvel <ard.biesheuvel@linaro.org>
    Acked-by: default avatarMichal Hocko <mhocko@suse.com>
    Reviewed-by: default avatarAndrew Morton <akpm@linux-foundation.org>
    Cc: Vlastimil Babka <vbabka@suse.cz>
    Cc: Mel Gorman <mgorman@techsingularity.net>
    Cc: Pavel Tatashin <pasha.tatashin@oracle.com>
    Cc: Paul Burton <paul.burton@imgtec.com>
    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>
    f59f1caf
page_alloc.c 215 KB