mm: make mmap_sem for write waits killable for mm syscalls

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

diff --git a/mm/util.c b/mm/util.c
index 6cc81e7..03b2377 100644 (file)
--- a/mm/util.c
+++ b/mm/util.c
@@ -289,7 +289,7 @@ EXPORT_SYMBOL_GPL(get_user_pages_fast);
 
 unsigned long vm_mmap_pgoff(struct file *file, unsigned long addr,
        unsigned long len, unsigned long prot,
-       unsigned long flag, unsigned long pgoff)
+       unsigned long flag, unsigned long pgoff, bool killable)
 {
        unsigned long ret;
        struct mm_struct *mm = current->mm;
@@ -297,7 +297,12 @@ unsigned long vm_mmap_pgoff(struct file *file, unsigned long addr,
 
        ret = security_mmap_file(file, prot, flag);
        if (!ret) {
-               down_write(&mm->mmap_sem);
+               if (killable) {
+                       if (down_write_killable(&mm->mmap_sem))
+                               return -EINTR;
+               } else {
+                       down_write(&mm->mmap_sem);
+               }
                ret = do_mmap_pgoff(file, addr, len, prot, flag, pgoff,
                                    &populate);
                up_write(&mm->mmap_sem);
@@ -307,6 +312,7 @@ unsigned long vm_mmap_pgoff(struct file *file, unsigned long addr,
        return ret;
 }
 
+/* XXX are all callers checking an error */
 unsigned long vm_mmap(struct file *file, unsigned long addr,
        unsigned long len, unsigned long prot,
        unsigned long flag, unsigned long offset)
@@ -316,7 +322,7 @@ unsigned long vm_mmap(struct file *file, unsigned long addr,
        if (unlikely(offset_in_page(offset)))
                return -EINVAL;
 
-       return vm_mmap_pgoff(file, addr, len, prot, flag, offset >> PAGE_SHIFT);
+       return vm_mmap_pgoff(file, addr, len, prot, flag, offset >> PAGE_SHIFT, false);
 }
 EXPORT_SYMBOL(vm_mmap);
 
@@ -346,6 +352,29 @@ void *page_rmapping(struct page *page)
        return __page_rmapping(page);
 }
 
+/*
+ * Return true if this page is mapped into pagetables.
+ * For compound page it returns true if any subpage of compound page is mapped.
+ */
+bool page_mapped(struct page *page)
+{
+       int i;
+
+       if (likely(!PageCompound(page)))
+               return atomic_read(&page->_mapcount) >= 0;
+       page = compound_head(page);
+       if (atomic_read(compound_mapcount_ptr(page)) >= 0)
+               return true;
+       if (PageHuge(page))
+               return false;
+       for (i = 0; i < hpage_nr_pages(page); i++) {
+               if (atomic_read(&page[i]._mapcount) >= 0)
+                       return true;
+       }
+       return false;
+}
+EXPORT_SYMBOL(page_mapped);
+
 struct anon_vma *page_anon_vma(struct page *page)
 {
        unsigned long mapping;