linux-kernel - [PATCH 38/94] mm/gup: Add mm_populate_vma() for use when the vma is known

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Date:   Wed, 28 Apr 2021 15:36:08 +0000
From:   Liam Howlett <liam.howlett@...cle.com>
To:     "maple-tree@...ts.infradead.org" <maple-tree@...ts.infradead.org>,
        "linux-mm@...ck.org" <linux-mm@...ck.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Andrew Morton <akpm@...ux-foundation.org>
CC:     Song Liu <songliubraving@...com>,
        Davidlohr Bueso <dave@...olabs.net>,
        "Paul E . McKenney" <paulmck@...nel.org>,
        Matthew Wilcox <willy@...radead.org>,
        Laurent Dufour <ldufour@...ux.ibm.com>,
        David Rientjes <rientjes@...gle.com>,
        Axel Rasmussen <axelrasmussen@...gle.com>,
        Suren Baghdasaryan <surenb@...gle.com>,
        Vlastimil Babka <vbabka@...e.cz>,
        Rik van Riel <riel@...riel.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Michel Lespinasse <walken.cr@...il.com>,
        Liam Howlett <liam.howlett@...cle.com>
Subject: [PATCH 38/94] mm/gup: Add 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>
---
 mm/gup.c      | 20 ++++++++++++++++++++
 mm/internal.h |  4 ++++
 2 files changed, 24 insertions(+)

diff --git a/mm/gup.c b/mm/gup.c
index c3a17b189064..48fe98ab0729 100644
--- a/mm/gup.c
+++ b/mm/gup.c
@@ -1468,6 +1468,26 @@ 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.
  *
diff --git a/mm/internal.h b/mm/internal.h
index 7ad55938d391..583f2f1e6ff8 100644
--- a/mm/internal.h
+++ b/mm/internal.h
@@ -346,6 +346,10 @@ static inline bool is_data_mapping(vm_flags_t flags)
 	return (flags & (VM_WRITE | VM_SHARED | VM_STACK)) == VM_WRITE;
 }
 
+/* mm/gup.c */
+extern void mm_populate_vma(struct vm_area_struct *vma, unsigned long start,
+			    unsigned long end);
+
 /* Maple tree operations using VMAs */
 /*
  * vma_mas_store() - Store a VMA in the maple tree.
-- 
2.30.2