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author | 2014-08-29 15:18:44 -0700 | |
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committer | 2014-08-29 16:28:16 -0700 | |
commit | b38af4721f59d0b564468f623b3e52a638195015 (patch) | |
tree | 1197f01ff4bec576a027157f42cffa6b238153f5 | |
parent | hugetlb_cgroup: use lockdep_assert_held rather than spin_is_locked (diff) | |
download | linux-b38af4721f59d0b564468f623b3e52a638195015.tar.gz linux-b38af4721f59d0b564468f623b3e52a638195015.tar.bz2 linux-b38af4721f59d0b564468f623b3e52a638195015.zip |
x86,mm: fix pte_special versus pte_numa
Sasha Levin has shown oopses on ffffea0003480048 and ffffea0003480008 at
mm/memory.c:1132, running Trinity on different 3.16-rc-next kernels:
where zap_pte_range() checks page->mapping to see if PageAnon(page).
Those addresses fit struct pages for pfns d2001 and d2000, and in each
dump a register or a stack slot showed d2001730 or d2000730: pte flags
0x730 are PCD ACCESSED PROTNONE SPECIAL IOMAP; and Sasha's e820 map has
a hole between cfffffff and 100000000, which would need special access.
Commit c46a7c817e66 ("x86: define _PAGE_NUMA by reusing software bits on
the PMD and PTE levels") has broken vm_normal_page(): a PROTNONE SPECIAL
pte no longer passes the pte_special() test, so zap_pte_range() goes on
to try to access a non-existent struct page.
Fix this by refining pte_special() (SPECIAL with PRESENT or PROTNONE) to
complement pte_numa() (SPECIAL with neither PRESENT nor PROTNONE). A
hint that this was a problem was that c46a7c817e66 added pte_numa() test
to vm_normal_page(), and moved its is_zero_pfn() test from slow to fast
path: This was papering over a pte_special() snag when the zero page was
encountered during zap. This patch reverts vm_normal_page() to how it
was before, relying on pte_special().
It still appears that this patch may be incomplete: aren't there other
places which need to be handling PROTNONE along with PRESENT? For
example, pte_mknuma() clears _PAGE_PRESENT and sets _PAGE_NUMA, but on a
PROT_NONE area, that would make it pte_special(). This is side-stepped
by the fact that NUMA hinting faults skipped PROT_NONE VMAs and there
are no grounds where a NUMA hinting fault on a PROT_NONE VMA would be
interesting.
Fixes: c46a7c817e66 ("x86: define _PAGE_NUMA by reusing software bits on the PMD and PTE levels")
Reported-by: Sasha Levin <sasha.levin@oracle.com>
Tested-by: Sasha Levin <sasha.levin@oracle.com>
Signed-off-by: Hugh Dickins <hughd@google.com>
Signed-off-by: Mel Gorman <mgorman@suse.de>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Cyrill Gorcunov <gorcunov@gmail.com>
Cc: Matthew Wilcox <matthew.r.wilcox@intel.com>
Cc: <stable@vger.kernel.org> [3.16]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-rw-r--r-- | arch/x86/include/asm/pgtable.h | 9 | ||||
-rw-r--r-- | mm/memory.c | 7 |
2 files changed, 10 insertions, 6 deletions
diff --git a/arch/x86/include/asm/pgtable.h b/arch/x86/include/asm/pgtable.h index 0ec056012618..aa97a070f09f 100644 --- a/arch/x86/include/asm/pgtable.h +++ b/arch/x86/include/asm/pgtable.h @@ -131,8 +131,13 @@ static inline int pte_exec(pte_t pte) static inline int pte_special(pte_t pte) { - return (pte_flags(pte) & (_PAGE_PRESENT|_PAGE_SPECIAL)) == - (_PAGE_PRESENT|_PAGE_SPECIAL); + /* + * See CONFIG_NUMA_BALANCING pte_numa in include/asm-generic/pgtable.h. + * On x86 we have _PAGE_BIT_NUMA == _PAGE_BIT_GLOBAL+1 == + * __PAGE_BIT_SOFTW1 == _PAGE_BIT_SPECIAL. + */ + return (pte_flags(pte) & _PAGE_SPECIAL) && + (pte_flags(pte) & (_PAGE_PRESENT|_PAGE_PROTNONE)); } static inline unsigned long pte_pfn(pte_t pte) diff --git a/mm/memory.c b/mm/memory.c index ab3537bcfed2..adeac306610f 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -751,7 +751,7 @@ struct page *vm_normal_page(struct vm_area_struct *vma, unsigned long addr, unsigned long pfn = pte_pfn(pte); if (HAVE_PTE_SPECIAL) { - if (likely(!pte_special(pte) || pte_numa(pte))) + if (likely(!pte_special(pte))) goto check_pfn; if (vma->vm_flags & (VM_PFNMAP | VM_MIXEDMAP)) return NULL; @@ -777,15 +777,14 @@ struct page *vm_normal_page(struct vm_area_struct *vma, unsigned long addr, } } + if (is_zero_pfn(pfn)) + return NULL; check_pfn: if (unlikely(pfn > highest_memmap_pfn)) { print_bad_pte(vma, addr, pte, NULL); return NULL; } - if (is_zero_pfn(pfn)) - return NULL; - /* * NOTE! We still have PageReserved() pages in the page tables. * eg. VDSO mappings can cause them to exist. |