The patch titled
Subject: khugepaged: collapse_pte_mapped_thp() flush the right range
has been added to the -mm tree. Its filename is
khugepaged-collapse_pte_mapped_thp-flush-the-right-range.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/khugepaged-collapse_pte_mapped_thp-flush-the-right-range.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/khugepaged-collapse_pte_mapped_thp-flush-the-right-range.patch
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------------------------------------------------------
From: Hugh Dickins <hughd@xxxxxxxxxx>
Subject: khugepaged: collapse_pte_mapped_thp() flush the right range
pmdp_collapse_flush() should be given the start address at which the huge
page is mapped, haddr: it was given addr, which at that point has been
used as a local variable, incremented to the end address of the extent.
Found by source inspection while chasing a hugepage locking bug, which I
then could not explain by this. At first I thought this was very bad;
then saw that all of the page translations that were not flushed would
actually still point to the right pages afterwards, so harmless; then
realized that I know nothing of how different architectures and models
cache intermediate paging structures, so maybe it matters after all -
particularly since the page table concerned is immediately freed.
Much easier to fix than to think about.
Link: http://lkml.kernel.org/r/alpine.LSU.2.11.2008021204390.27773@eggly.anvils
Fixes: 27e1f8273113 ("khugepaged: enable collapse pmd for pte-mapped THP")
Signed-off-by: Hugh Dickins <hughd@xxxxxxxxxx>
Acked-by: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx>
Cc: Andrea Arcangeli <aarcange@xxxxxxxxxx>
Cc: Mike Kravetz <mike.kravetz@xxxxxxxxxx>
Cc: Song Liu <songliubraving@xxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx> [5.4+]
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/khugepaged.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
--- a/mm/khugepaged.c~khugepaged-collapse_pte_mapped_thp-flush-the-right-range
+++ a/mm/khugepaged.c
@@ -1502,7 +1502,7 @@ void collapse_pte_mapped_thp(struct mm_s
/* step 4: collapse pmd */
ptl = pmd_lock(vma->vm_mm, pmd);
- _pmd = pmdp_collapse_flush(vma, addr, pmd);
+ _pmd = pmdp_collapse_flush(vma, haddr, pmd);
spin_unlock(ptl);
mm_dec_nr_ptes(mm);
pte_free(mm, pmd_pgtable(_pmd));
_
Patches currently in -mm which might be from hughd@xxxxxxxxxx are
mm-memcontrol-decouple-reference-counting-from-page-accounting-fix.patch
khugepaged-collapse_pte_mapped_thp-flush-the-right-range.patch
khugepaged-collapse_pte_mapped_thp-protect-the-pmd-lock.patch
khugepaged-retract_page_tables-remember-to-test-exit.patch
khugepaged-khugepaged_test_exit-check-mmget_still_valid.patch
