Merge tag 'defconfig-for-3.17' of git://git.kernel.org/pub/scm/linux/kernel/git/arm...

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

diff --git a/mm/filemap.c b/mm/filemap.c
index 65d44fd..af19a6b 100644 (file)
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -808,6 +808,17 @@ int __lock_page_killable(struct page *page)
 }
 EXPORT_SYMBOL_GPL(__lock_page_killable);
 
+/*
+ * Return values:
+ * 1 - page is locked; mmap_sem is still held.
+ * 0 - page is not locked.
+ *     mmap_sem has been released (up_read()), unless flags had both
+ *     FAULT_FLAG_ALLOW_RETRY and FAULT_FLAG_RETRY_NOWAIT set, in
+ *     which case mmap_sem is still held.
+ *
+ * If neither ALLOW_RETRY nor KILLABLE are set, will always return 1
+ * with the page locked and the mmap_sem unperturbed.
+ */
 int __lock_page_or_retry(struct page *page, struct mm_struct *mm,
                         unsigned int flags)
 {
@@ -1091,9 +1102,9 @@ no_page:
                if (WARN_ON_ONCE(!(fgp_flags & FGP_LOCK)))
                        fgp_flags |= FGP_LOCK;
 
-               /* Init accessed so avoit atomic mark_page_accessed later */
+               /* Init accessed so avoid atomic mark_page_accessed later */
                if (fgp_flags & FGP_ACCESSED)
-                       init_page_accessed(page);
+                       __SetPageReferenced(page);
 
                err = add_to_page_cache_lru(page, mapping, offset, radix_gfp_mask);
                if (unlikely(err)) {
@@ -1827,6 +1838,18 @@ static void do_async_mmap_readahead(struct vm_area_struct *vma,
  * The goto's are kind of ugly, but this streamlines the normal case of having
  * it in the page cache, and handles the special cases reasonably without
  * having a lot of duplicated code.
+ *
+ * vma->vm_mm->mmap_sem must be held on entry.
+ *
+ * If our return value has VM_FAULT_RETRY set, it's because
+ * lock_page_or_retry() returned 0.
+ * The mmap_sem has usually been released in this case.
+ * See __lock_page_or_retry() for the exception.
+ *
+ * If our return value does not have VM_FAULT_RETRY set, the mmap_sem
+ * has not been released.
+ *
+ * We never return with VM_FAULT_RETRY and a bit from VM_FAULT_ERROR set.
  */
 int filemap_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
 {