diff options
| author | Hugh Dickins <hughd@google.com> | 2013-10-16 13:47:08 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2013-10-16 21:35:53 -0700 |
| commit | 750e8165f5e87b6a142be953640eabb13a9d350a (patch) | |
| tree | b7df57b235d3cf1c3a8eb7956042d3018bc9ed46 | |
| parent | 5b808a2300a5ac45f4798ebfac8b367e98a4b692 (diff) | |
mm: fix BUG in __split_huge_page_pmd
Occasionally we hit the BUG_ON(pmd_trans_huge(*pmd)) at the end of
__split_huge_page_pmd(): seen when doing madvise(,,MADV_DONTNEED).
It's invalid: we don't always have down_write of mmap_sem there: a racing
do_huge_pmd_wp_page() might have copied-on-write to another huge page
before our split_huge_page() got the anon_vma lock.
Forget the BUG_ON, just go back and try again if this happens.
Signed-off-by: Hugh Dickins <hughd@google.com>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: David Rientjes <rientjes@google.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
| -rw-r--r-- | mm/huge_memory.c | 10 |
1 files changed, 9 insertions, 1 deletions
diff --git a/mm/huge_memory.c b/mm/huge_memory.c index 7489884682d..610e3df2768 100644 --- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -2697,6 +2697,7 @@ void __split_huge_page_pmd(struct vm_area_struct *vma, unsigned long address, mmun_start = haddr; mmun_end = haddr + HPAGE_PMD_SIZE; +again: mmu_notifier_invalidate_range_start(mm, mmun_start, mmun_end); spin_lock(&mm->page_table_lock); if (unlikely(!pmd_trans_huge(*pmd))) { @@ -2719,7 +2720,14 @@ void __split_huge_page_pmd(struct vm_area_struct *vma, unsigned long address, split_huge_page(page); put_page(page); - BUG_ON(pmd_trans_huge(*pmd)); + + /* + * We don't always have down_write of mmap_sem here: a racing + * do_huge_pmd_wp_page() might have copied-on-write to another + * huge page before our split_huge_page() got the anon_vma lock. + */ + if (unlikely(pmd_trans_huge(*pmd))) + goto again; } void split_huge_page_pmd_mm(struct mm_struct *mm, unsigned long address, |