smb3: request more credits on normal (non-large read/write) ops

[linux.git] / mm / memory.c

diff --git a/mm/memory.c b/mm/memory.c
index a52663c0612d4d1fb58a5be5ad34f4985ca80a89..e11ca9dd823f20c60dd0c20ff7567e34a84a1dda 100644 (file)
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -2994,6 +2994,28 @@ static vm_fault_t __do_fault(struct vm_fault *vmf)
        struct vm_area_struct *vma = vmf->vma;
        vm_fault_t ret;
 
+       /*
+        * Preallocate pte before we take page_lock because this might lead to
+        * deadlocks for memcg reclaim which waits for pages under writeback:
+        *                              lock_page(A)
+        *                              SetPageWriteback(A)
+        *                              unlock_page(A)
+        * lock_page(B)
+        *                              lock_page(B)
+        * pte_alloc_pne
+        *   shrink_page_list
+        *     wait_on_page_writeback(A)
+        *                              SetPageWriteback(B)
+        *                              unlock_page(B)
+        *                              # flush A, B to clear the writeback
+        */
+       if (pmd_none(*vmf->pmd) && !vmf->prealloc_pte) {
+               vmf->prealloc_pte = pte_alloc_one(vmf->vma->vm_mm);
+               if (!vmf->prealloc_pte)
+                       return VM_FAULT_OOM;
+               smp_wmb(); /* See comment in __pte_alloc() */
+       }
+
        ret = vma->vm_ops->fault(vmf);
        if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY |
                            VM_FAULT_DONE_COW)))
@@ -4077,8 +4099,8 @@ static int __follow_pte_pmd(struct mm_struct *mm, unsigned long address,
                goto out;
 
        if (range) {
-               range->start = address & PAGE_MASK;
-               range->end = range->start + PAGE_SIZE;
+               mmu_notifier_range_init(range, mm, address & PAGE_MASK,
+                                    (address & PAGE_MASK) + PAGE_SIZE);
                mmu_notifier_invalidate_range_start(range);
        }
        ptep = pte_offset_map_lock(mm, pmd, address, ptlp);