Eric Lee / smarc-ti-linux-kernel

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Commit 453c719261c0b4030b2676124adb6e81c5fb6833

Authored by Johannes Weiner
Committed by Linus Torvalds
1 parent 6a108a14fa
Exists in master and in 20 other branches dlt-processor-sdk-linux-03.00.00.04, newt-ti-linux-3.12.y, processor-sdk-linux-01.00.00, processor-sdk-linux-02.00.01, smarc-ti-linux-3.12.10, smarc-ti-linux-3.12.y, smarc-ti-linux-3.14.y, smarc-ti-linux-3.15.y, smarc-ti-lsk-linux-4.1.y, smarct3x-processor-sdk-04.01.00.06, smarct3x-processor-sdk-linux-02.00.01, smarct3x-processor-sdk-linux-03.00.00.04, smarct4x-800-processor-sdk-linux-02.00.01, smarct4x-processor-sdk-04.01.00.06, smarct4x-processor-sdk-linux-02.00.01, smarct4x-processor-sdk-linux-03.00.00.04, ti-linux-3.12.y, ti-linux-3.14.y, ti-linux-3.15.y, ti-lsk-linux-4.1.y

thp: keep highpte mapped until it is no longer needed 

Two users reported THP-related crashes on 32-bit x86 machines.  Their oops
reports indicated an invalid pte, and subsequent code inspection showed
that the highpte is actually used after unmap.

The fix is to unmap the pte only after all operations against it are
finished.

Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Reported-by: Ilya Dryomov <idryomov@gmail.com>
Reported-by: werner <w.landgraf@ru.ru>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Tested-by: Ilya Dryomov <idryomov@gmail.com>
Tested-by: Steven Rostedt <rostedt@goodmis.org
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Showing 1 changed file with 2 additions and 1 deletions Side-by-side Diff

... ... @@ -1837,9 +1837,9 @@
1837 1837 spin_lock(ptl);
1838 1838 isolated = __collapse_huge_page_isolate(vma, address, pte);
1839 1839 spin_unlock(ptl);
1840   - pte_unmap(pte);
1841 1840  
1842 1841 if (unlikely(!isolated)) {
  1842 + pte_unmap(pte);
1843 1843 spin_lock(&mm->page_table_lock);
1844 1844 BUG_ON(!pmd_none(*pmd));
1845 1845 set_pmd_at(mm, address, pmd, _pmd);
... ... @@ -1856,6 +1856,7 @@
1856 1856 anon_vma_unlock(vma->anon_vma);
1857 1857  
1858 1858 __collapse_huge_page_copy(pte, new_page, vma, address, ptl);
  1859 + pte_unmap(pte);
1859 1860 __SetPageUptodate(new_page);
1860 1861 pgtable = pmd_pgtable(_pmd);
1861 1862 VM_BUG_ON(page_count(pgtable) != 1);