• Linus Torvalds's avatar
    Merge tag 'memblock-v5.14-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/rppt/memblock · a412897f
    Linus Torvalds authored
    Pull memblock updates from Mike Rapoport:
     "Fix arm crashes caused by holes in the memory map.
    
      The coordination between freeing of unused memory map, pfn_valid() and
      core mm assumptions about validity of the memory map in various ranges
      was not designed for complex layouts of the physical memory with a lot
      of holes all over the place.
    
      Kefen Wang reported crashes in move_freepages() on a system with the
      following memory layout [1]:
    
    	node 0: [mem 0x0000000080a00000-0x00000000855fffff]
    	node 0: [mem 0x0000000086a00000-0x0000000087dfffff]
    	node 0: [mem 0x000000008bd00000-0x000000008c4fffff]
    	node 0: [mem 0x000000008e300000-0x000000008ecfffff]
    	node 0: [mem 0x0000000090d00000-0x00000000bfffffff]
    	node 0: [mem 0x00000000cc000000-0x00000000dc9fffff]
    	node 0: [mem 0x00000000de700000-0x00000000de9fffff]
    	node 0: [mem 0x00000000e0800000-0x00000000e0bfffff]
    	node 0: [mem 0x00000000f4b00000-0x00000000f6ffffff]
    	node 0: [mem 0x00000000fda00000-0x00000000ffffefff]
    
      These crashes can be mitigated by enabling CONFIG_HOLES_IN_ZONE on ARM
      and essentially turning pfn_valid_within() to pfn_valid() instead of
      having it hardwired to 1 on that architecture, but this would require
      to keep CONFIG_HOLES_IN_ZONE solely for this purpose.
    
      A cleaner approach is to update ARM's implementation of pfn_valid() to
      take into accounting rounding of the freed memory map to pageblock
      boundaries and make sure it returns true for PFNs that have memory map
      entries even if there is no physical memory backing those PFNs"
    
    Link: https://lore.kernel.org/lkml/2a1592ad-bc9d-4664-fd19-f7448a37edc0@huawei.com [1]
    
    * tag 'memblock-v5.14-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/rppt/memblock:
      arm: extend pfn_valid to take into account freed memory map alignment
      memblock: ensure there is no overflow in memblock_overlaps_region()
      memblock: align freed memory map on pageblock boundaries with SPARSEMEM
      memblock: free_unused_memmap: use pageblock units instead of MAX_ORDER
    a412897f
memblock.c 59.5 KB