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UPSTREAM: mm: fix the deadlock in finish_fault()

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Commit 63f3655f95 ("mm, memcg: fix reclaim deadlock with writeback")
fix the following ABBA deadlock by pre-allocating the pte page table
without holding the page lock.

	                                lock_page(A)
                                        SetPageWriteback(A)
                                        unlock_page(A)
  lock_page(B)
                                        lock_page(B)
  pte_alloc_one
    shrink_page_list
      wait_on_page_writeback(A)
                                        SetPageWriteback(B)
                                        unlock_page(B)

                                        # flush A, B to clear the writeback

Commit f9ce0be71d1f ("mm: Cleanup faultaround and finish_fault()
codepaths") reworked the relevant code but ignored this race.  This will
cause the deadlock above to appear again, so fix it.

Link: https://lkml.kernel.org/r/20210721074849.57004-1-zhengqi.arch@bytedance.com
Fixes: f9ce0be71d1f ("mm: Cleanup faultaround and finish_fault() codepaths")
Signed-off-by: Qi Zheng <zhengqi.arch@bytedance.com>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Vladimir Davydov <vdavydov.dev@gmail.com>
Cc: Muchun Song <songmuchun@bytedance.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
(cherry picked from commit e4dc3489143f84f7ed30be58b886bb6772f229b9)
Bug: 187129171
Signed-off-by: Connor O'Brien <connoro@google.com>
Change-Id: I80977e6cf60c938e98f17130233e776a2d097870
This commit is contained in:
Qi Zheng
2021-07-23 15:50:41 -07:00
committed by Connor O'Brien
parent 09ec66de84
commit 3649d38887
1 changed files with 10 additions and 1 deletions
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11
mm/memory.c
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@@ -4117,8 +4117,17 @@ vm_fault_t finish_fault(struct vm_fault *vmf)
return ret; return ret;
} }
if (unlikely(pte_alloc(vma->vm_mm, vmf->pmd))) if (vmf->prealloc_pte) {
vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd);
if (likely(pmd_none(*vmf->pmd))) {
mm_inc_nr_ptes(vma->vm_mm);
pmd_populate(vma->vm_mm, vmf->pmd, vmf->prealloc_pte);
vmf->prealloc_pte = NULL;
}
spin_unlock(vmf->ptl);
} else if (unlikely(pte_alloc(vma->vm_mm, vmf->pmd))) {
return VM_FAULT_OOM; return VM_FAULT_OOM;
}
} }
/* See comment in handle_pte_fault() */ /* See comment in handle_pte_fault() */