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mm: hugetlb: fix a race between isolating and freeing page

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There is a race between isolate_huge_page() and __free_huge_page().

  CPU0:                                     CPU1:

  if (PageHuge(page))
                                            put_page(page)
                                              __free_huge_page(page)
                                                  spin_lock(&hugetlb_lock)
                                                  update_and_free_page(page)
                                                    set_compound_page_dtor(page,
                                                      NULL_COMPOUND_DTOR)
                                                  spin_unlock(&hugetlb_lock)
    isolate_huge_page(page)
      // trigger BUG_ON
      VM_BUG_ON_PAGE(!PageHead(page), page)
      spin_lock(&hugetlb_lock)
      page_huge_active(page)
        // trigger BUG_ON
        VM_BUG_ON_PAGE(!PageHuge(page), page)
      spin_unlock(&hugetlb_lock)

When we isolate a HugeTLB page on CPU0.  Meanwhile, we free it to the
buddy allocator on CPU1.  Then, we can trigger a BUG_ON on CPU0, because
it is already freed to the buddy allocator.

Link: https://lkml.kernel.org/r/20210115124942.46403-5-songmuchun@bytedance.com
Fixes: c8721bbbdd ("mm: memory-hotplug: enable memory hotplug to handle hugepage")
Signed-off-by: Muchun Song <songmuchun@bytedance.com>
Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Reviewed-by: Oscar Salvador <osalvador@suse.de>
Cc: David Hildenbrand <david@redhat.com>
Cc: Yang Shi <shy828301@gmail.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Muchun Song 2021-02-04 18:32:10 -08:00 committed by Linus Torvalds
parent 7ffddd499b
commit 0eb2df2b56
1 changed files with 2 additions and 2 deletions
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4
mm/hugetlb.c
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@ -5594,9 +5594,9 @@ bool isolate_huge_page(struct page *page, struct list_head *list)
{
bool ret = true;
VM_BUG_ON_PAGE(!PageHead(page), page);
spin_lock(&hugetlb_lock);
if (!page_huge_active(page) || !get_page_unless_zero(page)) {
if (!PageHeadHuge(page) || !page_huge_active(page) ||
!get_page_unless_zero(page)) {
ret = false;
goto unlock;
}