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Date: Wed, 28 Apr 2021 15:36:12 +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 47/94] mm/mmap: Add do_mas_munmap() and wraper for
__do_munmap()
To avoid extra tree work, it is necessary to support passing in a maple state
to key functions. Start this work with __do_munmap().
Signed-off-by: Liam R. Howlett <Liam.Howlett@...cle.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_struct *start,
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@...p.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 location.
+ * @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 = start + PAGE_ALIGN(len);
- if (end == start)
- return -EINVAL;
-
- /* arch_unmap() might do unmaps itself. */
- arch_unmap(mm, start, end);
-
- /* Find the first overlapping VMA */
- vma = mas_find(&mas, end - 1);
- if (!vma)
- return 0;
-
- mas.last = end - 1;
+ struct vm_area_struct *prev, *last;
/* we have start < vma->vm_end */
/*
@@ -2465,8 +2455,8 @@ int __do_munmap(struct mm_struct *mm, unsigned long start, size_t len,
return error;
prev = vma;
vma = vma_next(mm, prev);
- mas.index = start;
- mas_reset(&mas);
+ mas->index = start;
+ mas_reset(mas);
} else {
prev = vma->vm_prev;
}
@@ -2482,7 +2472,7 @@ int __do_munmap(struct mm_struct *mm, unsigned long start, size_t len,
if (error)
return error;
vma = vma_next(mm, prev);
- mas_reset(&mas);
+ mas_reset(mas);
}
@@ -2509,7 +2499,7 @@ int __do_munmap(struct mm_struct *mm, unsigned long start, size_t len,
*/
mm->map_count -= 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);
/* Detach vmas from the MM linked list */
vma->vm_prev = NULL;
@@ -2546,6 +2536,59 @@ int __do_munmap(struct mm_struct *mm, unsigned long start, size_t len,
return downgrade ? 1 : 0;
}
+/*
+ * 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 = start + PAGE_ALIGN(len);
+ if (end == start)
+ return -EINVAL;
+
+ /* arch_unmap() might do unmaps itself. */
+ arch_unmap(mm, start, end);
+
+ /* Find the first overlapping VMA */
+ vma = mas_find(mas, end - 1);
+ if (!vma)
+ return 0;
+
+ mas->last = 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() calls.
+ * @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,
}
/* 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;
/*
@@ -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 != newbrk)
mas_reset(mas); // cause a re-walk for the first overlap.
- ret = __do_munmap(mm, newbrk, oldbrk - newbrk, uf, true);
+ ret = do_mas_munmap(mas, mm, newbrk, oldbrk-newbrk, uf, true);
goto munmap_full_vma;
}
--
2.30.2
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