@@ -4026,8 +4026,17 @@ vm_fault_t finish_fault(struct vm_fault *vmf)
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;
+ }
}
/* See comment in handle_pte_fault() */
The commit 63f3655f9501 ("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 The commit f9ce0be71d1f ("mm: Cleanup faultaround and finish_fault() codepaths") rework the relevant code but ignore this race. This will cause the deadlock above to appear again, so fix it. 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: <stable@vger.kernel.org> --- Changelog in v1 -> v2: - Update commit log mm/memory.c | 11 ++++++++++- 1 file changed, 10 insertions(+), 1 deletion(-) -- 2.11.0