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From:   Liam Howlett <liam.howlett@oracle.com>
To:     "maple-tree@lists.infradead.org" <maple-tree@lists.infradead.org>,
        "linux-mm@kvack.org" <linux-mm@kvack.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        Andrew Morton <akpm@linux-foundation.org>
CC:     Song Liu <songliubraving@fb.com>,
        Davidlohr Bueso <dave@stgolabs.net>,
        "Paul E . McKenney" <paulmck@kernel.org>,
        Matthew Wilcox <willy@infradead.org>,
        Laurent Dufour <ldufour@linux.ibm.com>,
        David Rientjes <rientjes@google.com>,
        Axel Rasmussen <axelrasmussen@google.com>,
        Suren Baghdasaryan <surenb@google.com>,
        Vlastimil Babka <vbabka@suse.cz>,
        Rik van Riel <riel@surriel.com>,
        Peter Zijlstra <peterz@infradead.org>,
        Michel Lespinasse <walken.cr@gmail.com>,
        Liam Howlett <liam.howlett@oracle.com>
Subject: [PATCH 47/94] mm/mmap: Add do_mas_munmap() and wraper for
 __do_munmap()
Thread-Topic: [PATCH 47/94] mm/mmap: Add do_mas_munmap() and wraper for
 __do_munmap()
Thread-Index: AQHXPEQ321aiStTYNEGXcgYKyqW8Uw==
Date:   Wed, 28 Apr 2021 15:36:12 +0000
Message-ID: <20210428153542.2814175-48-Liam.Howlett@Oracle.com>
References: <20210428153542.2814175-1-Liam.Howlett@Oracle.com>
In-Reply-To: <20210428153542.2814175-1-Liam.Howlett@Oracle.com>
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To avoid extra tree work, it is necessary to support passing in a maple sta=
te
to key functions.  Start this work with __do_munmap().

Signed-off-by: Liam R. Howlett <Liam.Howlett@Oracle.com>
---
 mm/mmap.c | 107 ++++++++++++++++++++++++++++++++++++++----------------
 1 file changed, 75 insertions(+), 32 deletions(-)

diff --git a/mm/mmap.c b/mm/mmap.c
index 0106b5accd7c..6fa93606e62b 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -2413,34 +2413,24 @@ static inline int unlock_range(struct vm_area_struc=
t *start,
=20
 	return count;
 }
-/* Munmap is split into 2 main parts -- this part which finds
- * what needs doing, and the areas themselves, which do the
- * work.  This now handles partial unmappings.
- * Jeremy Fitzhardinge <jeremy@goop.org>
+
+/* do_mas_align_munmap() - munmap the aligned region from @start to @end.
+ *
+ * @mas: The maple_state, ideally set up to alter the correct tree locatio=
n.
+ * @vma: The starting vm_area_struct
+ * @mm: The mm_struct
+ * @start: The aligned start address to munmap.
+ * @end: The aligned end address to munmap.
+ * @uf: The userfaultfd list_head
+ * @downgrade: Set to true to attempt a downwrite of the mmap_sem
+ *
+ *
  */
-int __do_munmap(struct mm_struct *mm, unsigned long start, size_t len,
-		struct list_head *uf, bool downgrade)
+static int do_mas_align_munmap(struct ma_state *mas, struct vm_area_struct=
 *vma,
+	       struct mm_struct *mm, unsigned long start, unsigned long end,
+	       struct list_head *uf, bool downgrade)
 {
-	unsigned long end;
-	struct vm_area_struct *vma, *prev, *last;
-	MA_STATE(mas, &mm->mm_mt, start, start);
-
-	if ((offset_in_page(start)) || start > TASK_SIZE || len > TASK_SIZE-start=
)
-		return -EINVAL;
-
-	end =3D start + PAGE_ALIGN(len);
-	if (end =3D=3D start)
-		return -EINVAL;
-
-	 /* arch_unmap() might do unmaps itself.  */
-	arch_unmap(mm, start, end);
-
-	/* Find the first overlapping VMA */
-	vma =3D mas_find(&mas, end - 1);
-	if (!vma)
-		return 0;
-
-	mas.last =3D end - 1;
+	struct vm_area_struct *prev, *last;
 	/* we have start < vma->vm_end  */
=20
 	/*
@@ -2465,8 +2455,8 @@ int __do_munmap(struct mm_struct *mm, unsigned long s=
tart, size_t len,
 			return error;
 		prev =3D vma;
 		vma =3D vma_next(mm, prev);
-		mas.index =3D start;
-		mas_reset(&mas);
+		mas->index =3D start;
+		mas_reset(mas);
 	} else {
 		prev =3D vma->vm_prev;
 	}
@@ -2482,7 +2472,7 @@ int __do_munmap(struct mm_struct *mm, unsigned long s=
tart, size_t len,
 		if (error)
 			return error;
 		vma =3D vma_next(mm, prev);
-		mas_reset(&mas);
+		mas_reset(mas);
 	}
=20
=20
@@ -2509,7 +2499,7 @@ int __do_munmap(struct mm_struct *mm, unsigned long s=
tart, size_t len,
 	 */
 	mm->map_count -=3D unlock_range(vma, &last, end);
 	/* Drop removed area from the tree */
-	mas_store_gfp(&mas, NULL, GFP_KERNEL);
+	mas_store_gfp(mas, NULL, GFP_KERNEL);
=20
 	/* Detach vmas from the MM linked list */
 	vma->vm_prev =3D NULL;
@@ -2546,6 +2536,59 @@ int __do_munmap(struct mm_struct *mm, unsigned long =
start, size_t len,
 	return downgrade ? 1 : 0;
 }
=20
+/*
+ * do_mas_munmap() - munmap a given range.
+ * @mas: The maple state
+ * @mm: The mm_struct
+ * @start: The start address to munmap
+ * @len: The length of the range to munmap
+ * @uf: The userfaultfd list_head
+ * @downgrade: set to true if the user wants to attempt to write_downgrade=
 the
+ * mmap_sem
+ *
+ * This function takes a @mas that is in the correct state to remove the
+ * mapping(s).  The @len will be aligned and any arch_unmap work will be
+ * preformed.
+ */
+int do_mas_munmap(struct ma_state *mas, struct mm_struct *mm,
+		  unsigned long start, size_t len, struct list_head *uf,
+		  bool downgrade)
+{
+	unsigned long end;
+	struct vm_area_struct *vma;
+
+	if ((offset_in_page(start)) || start > TASK_SIZE || len > TASK_SIZE-start=
)
+		return -EINVAL;
+
+	end =3D start + PAGE_ALIGN(len);
+	if (end =3D=3D start)
+		return -EINVAL;
+
+	 /* arch_unmap() might do unmaps itself.  */
+	arch_unmap(mm, start, end);
+
+	/* Find the first overlapping VMA */
+	vma =3D mas_find(mas, end - 1);
+	if (!vma)
+		return 0;
+
+	mas->last =3D end - 1;
+	return do_mas_align_munmap(mas, vma, mm, start, end, uf, downgrade);
+}
+
+int __do_munmap(struct mm_struct *mm, unsigned long start, size_t len,
+		struct list_head *uf, bool downgrade)
+{
+	MA_STATE(mas, &mm->mm_mt, start, start);
+	return do_mas_munmap(&mas, mm, start, len, uf, downgrade);
+}
+
+/* do_munmap() - Wrapper function for non-maple tree aware do_munmap() cal=
ls.
+ * @mm: The mm_struct
+ * @start: The start address to munmap
+ * @len: The length to be munmapped.
+ * @uf: The userfaultfd list_head
+ */
 int do_munmap(struct mm_struct *mm, unsigned long start, size_t len,
 	      struct list_head *uf)
 {
@@ -2583,7 +2626,7 @@ unsigned long mmap_region(struct file *file, unsigned=
 long addr,
 	}
=20
 	/* Unmap any existing mapping in the area */
-	if (do_munmap(mm, addr, len, uf))
+	if (do_mas_munmap(&mas, mm, addr, len, uf, false))
 		return -ENOMEM;
=20
 	/*
@@ -2937,7 +2980,7 @@ static int do_brk_munmap(struct ma_state *mas, struct=
 vm_area_struct *vma,
 		mas_set(mas, newbrk);
 		if (vma->vm_start !=3D newbrk)
 			mas_reset(mas); // cause a re-walk for the first overlap.
-		ret =3D __do_munmap(mm, newbrk, oldbrk - newbrk, uf, true);
+		ret =3D do_mas_munmap(mas, mm, newbrk, oldbrk-newbrk, uf, true);
 		goto munmap_full_vma;
 	}
=20
--=20
2.30.2