tcp: enforce tcp_min_snd_mss in tcp_mtu_probing()

[pandora-kernel.git] / mm / huge_memory.c

diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index 9d40694..1b04121 100644 (file)
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -997,6 +997,18 @@ out:
        return ret;
 }
 
+/*
+ * FOLL_FORCE can write to even unwritable pmd's, but only
+ * after we've gone through a COW cycle and they are dirty.
+ */
+static inline bool can_follow_write_pmd(pmd_t pmd, struct page *page,
+                                       unsigned int flags)
+{
+       return pmd_write(pmd) ||
+               ((flags & FOLL_FORCE) && (flags & FOLL_COW) &&
+                page && PageAnon(page));
+}
+
 struct page *follow_trans_huge_pmd(struct mm_struct *mm,
                                   unsigned long addr,
                                   pmd_t *pmd,
@@ -1006,11 +1018,12 @@ struct page *follow_trans_huge_pmd(struct mm_struct *mm,
 
        assert_spin_locked(&mm->page_table_lock);
 
-       if (flags & FOLL_WRITE && !pmd_write(*pmd))
-               goto out;
-
        page = pmd_page(*pmd);
        VM_BUG_ON(!PageHead(page));
+
+       if (flags & FOLL_WRITE && !can_follow_write_pmd(*pmd, page, flags))
+               return NULL;
+
        if (flags & FOLL_TOUCH) {
                pmd_t _pmd;
                /*
@@ -1029,7 +1042,6 @@ struct page *follow_trans_huge_pmd(struct mm_struct *mm,
        if (flags & FOLL_GET)
                get_page_foll(page);
 
-out:
        return page;
 }