mm/rmap: split try_to_munlock from try_to_unmap

The behaviour of try_to_unmap_one() is difficult to follow because it
performs different operations based on a fairly large set of flags used in
different combinations.

TTU_MUNLOCK is one such flag.  However it is exclusively used by
try_to_munlock() which specifies no other flags.  Therefore rather than
overload try_to_unmap_one() with unrelated behaviour split this out into
it's own function and remove the flag.

Link: https://lkml.kernel.org/r/20210616105937.23201-4-apopple@nvidia.com
Signed-off-by: Alistair Popple <apopple@nvidia.com>
Reviewed-by: Ralph Campbell <rcampbell@nvidia.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Cc: Ben Skeggs <bskeggs@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Jason Gunthorpe <jgg@nvidia.com>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: "Matthew Wilcox (Oracle)" <willy@infradead.org>
Cc: Peter Xu <peterx@redhat.com>
Cc: Shakeel Butt <shakeelb@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 6 insertions, 6 deletions

diff --git a/mm/mlock.c b/mm/mlock.c
index df590fda5688..4ab757ab6fe8 100644
--- a/mm/mlock.c
+++ b/mm/mlock.c
@@ -108,7 +108,7 @@ void mlock_vma_page(struct page *page)
 /*
  * Finish munlock after successful page isolation
  *
- * Page must be locked. This is a wrapper for try_to_munlock()
+ * Page must be locked. This is a wrapper for page_mlock()
  * and putback_lru_page() with munlock accounting.
  */
 static void __munlock_isolated_page(struct page *page)
@@ -118,7 +118,7 @@ static void __munlock_isolated_page(struct page *page)
 	 * and we don't need to check all the other vmas.
 	 */
 	if (page_mapcount(page) > 1)
-		try_to_munlock(page);
+		page_mlock(page);
 
 	/* Did try_to_unlock() succeed or punt? */
 	if (!PageMlocked(page))
@@ -158,7 +158,7 @@ static void __munlock_isolation_failed(struct page *page)
  * munlock()ed or munmap()ed, we want to check whether other vmas hold the
  * page locked so that we can leave it on the unevictable lru list and not
  * bother vmscan with it.  However, to walk the page's rmap list in
- * try_to_munlock() we must isolate the page from the LRU.  If some other
+ * page_mlock() we must isolate the page from the LRU.  If some other
  * task has removed the page from the LRU, we won't be able to do that.
  * So we clear the PageMlocked as we might not get another chance.  If we
  * can't isolate the page, we leave it for putback_lru_page() and vmscan
@@ -168,7 +168,7 @@ unsigned int munlock_vma_page(struct page *page)
 {
 	int nr_pages;
 
-	/* For try_to_munlock() and to serialize with page migration */
+	/* For page_mlock() and to serialize with page migration */
 	BUG_ON(!PageLocked(page));
 	VM_BUG_ON_PAGE(PageTail(page), page);
 
@@ -205,7 +205,7 @@ static int __mlock_posix_error_return(long retval)
  *
  * The fast path is available only for evictable pages with single mapping.
  * Then we can bypass the per-cpu pvec and get better performance.
- * when mapcount > 1 we need try_to_munlock() which can fail.
+ * when mapcount > 1 we need page_mlock() which can fail.
  * when !page_evictable(), we need the full redo logic of putback_lru_page to
  * avoid leaving evictable page in unevictable list.
  *
@@ -414,7 +414,7 @@ static unsigned long __munlock_pagevec_fill(struct pagevec *pvec,
  *
  * We don't save and restore VM_LOCKED here because pages are
  * still on lru.  In unmap path, pages might be scanned by reclaim
- * and re-mlocked by try_to_{munlock|unmap} before we unmap and
+ * and re-mlocked by page_mlock/try_to_unmap before we unmap and
  * free them.  This will result in freeing mlocked pages.
  */
 void munlock_vma_pages_range(struct vm_area_struct *vma,