Re: [PATCH v2 1/2] mm/gup: fixup for 9947ea2c1e608e32 "mm/gup: track FOLL_PIN pages"

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On 3/2/20 4:25 PM, Claudio Imbrenda wrote:
In case pin fails, we need to unpin, a simple put_page will not be enough

fixup for commit 9947ea2c1e608e32 ("mm/gup: track FOLL_PIN pages")

it can be simply squashed in

Signed-off-by: Claudio Imbrenda <imbrenda@xxxxxxxxxxxxx>
---
  mm/gup.c | 46 +++++++++++++++++++++++-----------------------
  1 file changed, 23 insertions(+), 23 deletions(-)



Looks good, thanks for fixing this.


thanks,
--
John Hubbard
NVIDIA


diff --git a/mm/gup.c b/mm/gup.c
index f589299b0d4a..81a95fbe9901 100644
--- a/mm/gup.c
+++ b/mm/gup.c
@@ -116,6 +116,28 @@ static __maybe_unused struct page *try_grab_compound_head(struct page *page,
  	return NULL;
  }
+static void put_compound_head(struct page *page, int refs, unsigned int flags)
+{
+	if (flags & FOLL_PIN) {
+		mod_node_page_state(page_pgdat(page), NR_FOLL_PIN_RELEASED,
+				    refs);
+
+		if (hpage_pincount_available(page))
+			hpage_pincount_sub(page, refs);
+		else
+			refs *= GUP_PIN_COUNTING_BIAS;
+	}
+
+	VM_BUG_ON_PAGE(page_ref_count(page) < refs, page);
+	/*
+	 * Calling put_page() for each ref is unnecessarily slow. Only the last
+	 * ref needs a put_page().
+	 */
+	if (refs > 1)
+		page_ref_sub(page, refs - 1);
+	put_page(page);
+}
+
  /**
   * try_grab_page() - elevate a page's refcount by a flag-dependent amount
   *
@@ -2134,7 +2156,7 @@ static int gup_pte_range(pmd_t pmd, unsigned long addr, unsigned long end,
  			goto pte_unmap;
if (unlikely(pte_val(pte) != pte_val(*ptep))) {
-			put_page(head);
+			put_compound_head(head, 1, flags);
  			goto pte_unmap;
  		}
@@ -2267,28 +2289,6 @@ static int record_subpages(struct page *page, unsigned long addr,
  	return nr;
  }
-static void put_compound_head(struct page *page, int refs, unsigned int flags)
-{
-	if (flags & FOLL_PIN) {
-		mod_node_page_state(page_pgdat(page), NR_FOLL_PIN_RELEASED,
-				    refs);
-
-		if (hpage_pincount_available(page))
-			hpage_pincount_sub(page, refs);
-		else
-			refs *= GUP_PIN_COUNTING_BIAS;
-	}
-
-	VM_BUG_ON_PAGE(page_ref_count(page) < refs, page);
-	/*
-	 * Calling put_page() for each ref is unnecessarily slow. Only the last
-	 * ref needs a put_page().
-	 */
-	if (refs > 1)
-		page_ref_sub(page, refs - 1);
-	put_page(page);
-}
-
  #ifdef CONFIG_ARCH_HAS_HUGEPD
  static unsigned long hugepte_addr_end(unsigned long addr, unsigned long end,
  				      unsigned long sz)





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