linux-kernel - [PATCH 13/28] mm/gup: Expose mm_populate

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Date:   Thu, 10 Dec 2020 12:03:47 -0500
From:   "Liam R. Howlett" <Liam.Howlett@...cle.com>
To:     maple-tree@...ts.infradead.org, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org
Cc:     Andrew Morton <akpm@...gle.com>, Song Liu <songliubraving@...com>,
        Davidlohr Bueso <dave@...olabs.net>,
        "Paul E . McKenney" <paulmck@...nel.org>,
        Matthew Wilcox <willy@...radead.org>,
        Jerome Glisse <jglisse@...hat.com>,
        David Rientjes <rientjes@...gle.com>,
        Axel Rasmussen <axelrasmussen@...gle.com>,
        Suren Baghdasaryan <surenb@...gle.com>,
        Vlastimil Babka <vbabka@...e.cz>
Subject: [PATCH 13/28] mm/gup: Expose mm_populate_vma() for use when the vma is known

When a vma is known, avoid calling mm_populate to search for the vma to
populate.

Signed-off-by: Liam R. Howlett <Liam.Howlett@...cle.com>
---
 include/linux/mm.h |  4 ++++
 mm/gup.c           | 20 ++++++++++++++++++++
 2 files changed, 24 insertions(+)

diff --git a/include/linux/mm.h b/include/linux/mm.h
index 1bfa2ee41187d..6cc8825f26414 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -2587,8 +2587,12 @@ static inline void mm_populate(unsigned long addr, unsigned long len)
 	/* Ignore errors */
 	(void) __mm_populate(addr, len, 1);
 }
+extern void mm_populate_vma(struct vm_area_struct *vma, unsigned long start,
+			    unsigned long end);
 #else
 static inline void mm_populate(unsigned long addr, unsigned long len) {}
+void mm_populate_vma(struct vm_area_struct *vma, unsigned long start,
+		     unsigned long end) {}
 #endif
 
 /* These take the mm semaphore themselves */
diff --git a/mm/gup.c b/mm/gup.c
index 102877ed77a4b..522f8fd491ead 100644
--- a/mm/gup.c
+++ b/mm/gup.c
@@ -1431,6 +1431,26 @@ long populate_vma_page_range(struct vm_area_struct *vma,
 				NULL, NULL, locked);
 }
 
+/*
+ * mm_populate_vma() - Populate a single range in a single vma.
+ * @vma: The vma to populate.
+ * @start: The start address to populate
+ * @end: The end address to stop populating
+ *
+ * Note: Ignores errors.
+ */
+void mm_populate_vma(struct vm_area_struct *vma, unsigned long start,
+		unsigned long end)
+{
+	struct mm_struct *mm = current->mm;
+	int locked = 1;
+
+	mmap_read_lock(mm);
+	populate_vma_page_range(vma, start, end, &locked);
+	if (locked)
+		mmap_read_unlock(mm);
+}
+
 /*
  * __mm_populate - populate and/or mlock pages within a range of address space.
  *
-- 
2.28.0