• Kirill A. Shutemov's avatar
    x86/mm: Fix regression with huge pages on PAE · 70f15287
    Kirill A. Shutemov authored
    Recent PAT patchset has caused issue on 32-bit PAE machines:
    
      page:eea45000 count:0 mapcount:-128 mapping:  (null) index:0x0 flags: 0x40000000()
      page dumped because: VM_BUG_ON_PAGE(page_mapcount(page) < 0)
      ------------[ cut here ]------------
      kernel BUG at /home/build/linux-boris/mm/huge_memory.c:1485!
      invalid opcode: 0000 [#1] SMP
      [...]
      Call Trace:
       unmap_single_vma
       ? __wake_up
       unmap_vmas
       unmap_region
       do_munmap
       vm_munmap
       SyS_munmap
       do_fast_syscall_32
       ? __do_page_fault
       sysenter_past_esp
      Code: ...
      EIP: [<c11bde80>] zap_huge_pmd+0x240/0x260 SS:ESP 0068:f6459d98
    
    The problem is in pmd_pfn_mask() and pmd_flags_mask(). These
    helpers use PMD_PAGE_MASK to calculate resulting mask.
    PMD_PAGE_MASK is 'unsigned long', not 'unsigned long long' as
    phys_addr_t is on 32-bit PAE (ARCH_PHYS_ADDR_T_64BIT). As a
    result, the upper bits of resulting mask get truncated.
    
    pud_pfn_mask() and pud_flags_mask() aren't problematic since we
    don't have PUD page table level on 32-bit systems, but it's
    reasonable to keep them consistent with PMD counterpart.
    
    Introduce PHYSICAL_PMD_PAGE_MASK and PHYSICAL_PUD_PAGE_MASK in
    addition to existing PHYSICAL_PAGE_MASK and reworks helpers to
    use them.
    Reported-and-Tested-by: default avatarBoris Ostrovsky <boris.ostrovsky@oracle.com>
    Signed-off-by: default avatarKirill A. Shutemov <kirill.shutemov@linux.intel.com>
    [ Fix -Woverflow warnings from the realmode code. ]
    Signed-off-by: default avatarBorislav Petkov <bp@suse.de>
    Reviewed-by: default avatarToshi Kani <toshi.kani@hpe.com>
    Cc: Andrew Morton <akpm@linux-foundation.org>
    Cc: Andy Lutomirski <luto@amacapital.net>
    Cc: Borislav Petkov <bp@alien8.de>
    Cc: Brian Gerst <brgerst@gmail.com>
    Cc: Denys Vlasenko <dvlasenk@redhat.com>
    Cc: H. Peter Anvin <hpa@zytor.com>
    Cc: Jürgen Gross <jgross@suse.com>
    Cc: Linus Torvalds <torvalds@linux-foundation.org>
    Cc: Mel Gorman <mgorman@suse.de>
    Cc: Peter Zijlstra <peterz@infradead.org>
    Cc: Thomas Gleixner <tglx@linutronix.de>
    Cc: elliott@hpe.com
    Cc: konrad.wilk@oracle.com
    Cc: linux-mm <linux-mm@kvack.org>
    Fixes: f70abb0f ("x86/asm: Fix pud/pmd interfaces to handle large PAT bit")
    Link: http://lkml.kernel.org/r/1448878233-11390-2-git-send-email-bp@alien8.deSigned-off-by: default avatarIngo Molnar <mingo@kernel.org>
    Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
    70f15287
video.c 7.17 KB