mremap: don't do uneccesary checks if new_len == old_len

[cascardo/linux.git] / mm / memory.c

diff --git a/mm/memory.c b/mm/memory.c
index 388dcf9..2961fb6 100644 (file)
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -61,6 +61,7 @@
 #include <linux/string.h>
 #include <linux/dma-debug.h>
 #include <linux/debugfs.h>
+#include <linux/userfaultfd_k.h>
 
 #include <asm/io.h>
 #include <asm/pgalloc.h>
@@ -2685,6 +2686,12 @@ static int do_anonymous_page(struct mm_struct *mm, struct vm_area_struct *vma,
                page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
                if (!pte_none(*page_table))
                        goto unlock;
+               /* Deliver the page fault to userland, check inside PT lock */
+               if (userfaultfd_missing(vma)) {
+                       pte_unmap_unlock(page_table, ptl);
+                       return handle_userfault(vma, address, flags,
+                                               VM_UFFD_MISSING);
+               }
                goto setpte;
        }
 
@@ -2713,6 +2720,15 @@ static int do_anonymous_page(struct mm_struct *mm, struct vm_area_struct *vma,
        if (!pte_none(*page_table))
                goto release;
 
+       /* Deliver the page fault to userland, check inside PT lock */
+       if (userfaultfd_missing(vma)) {
+               pte_unmap_unlock(page_table, ptl);
+               mem_cgroup_cancel_charge(page, memcg);
+               page_cache_release(page);
+               return handle_userfault(vma, address, flags,
+                                       VM_UFFD_MISSING);
+       }
+
        inc_mm_counter_fast(mm, MM_ANONPAGES);
        page_add_new_anon_rmap(page, vma, address);
        mem_cgroup_commit_charge(page, memcg, false);