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-rw-r--r--mm/huge_memory.c10
1 files changed, 9 insertions, 1 deletions
diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index 7489884..610e3df 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,
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