linux-kernel - [PATCH 07/14] mm: Remove re-walk from mmap

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Date:   Wed, 31 May 2023 22:15:58 -0400
From:   "Liam R. Howlett" <Liam.Howlett@...cle.com>
To:     Andrew Morton <akpm@...ux-foundation.org>
Cc:     maple-tree@...ts.infradead.org, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org,
        "Liam R. Howlett" <Liam.Howlett@...cle.com>
Subject: [PATCH 07/14] mm: Remove re-walk from mmap_region()

Using vma_iter_set() will reset the tree and cause a re-walk.  Use
vmi_iter_config() to set the write to a sub-set of the range.  Change
the file case to also use vmi_iter_config() so that the end is correctly
set.

Signed-off-by: Liam R. Howlett <Liam.Howlett@...cle.com>
---
 mm/internal.h | 8 ++++++++
 mm/mmap.c     | 4 ++--
 2 files changed, 10 insertions(+), 2 deletions(-)

diff --git a/mm/internal.h b/mm/internal.h
index 24437f11d3c2..cdf06f680d6e 100644
--- a/mm/internal.h
+++ b/mm/internal.h
@@ -1034,6 +1034,14 @@ static inline bool vma_soft_dirty_enabled(struct vm_area_struct *vma)
 	return !(vma->vm_flags & VM_SOFTDIRTY);
 }
 
+static inline void vma_iter_config(struct vma_iterator *vmi,
+		unsigned long index, unsigned long last)
+{
+	MAS_BUG_ON(&vmi->mas, vmi->mas.node != MAS_START &&
+		   (vmi->mas.index > index || vmi->mas.last < index));
+	__mas_set_range(&vmi->mas, index, last - 1);
+}
+
 /*
  * VMA Iterator functions shared between nommu and mmap
  */
diff --git a/mm/mmap.c b/mm/mmap.c
index fd3f505b40cc..8b3e58d6ac40 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -2659,7 +2659,7 @@ unsigned long mmap_region(struct file *file, unsigned long addr,
 		goto unacct_error;
 	}
 
-	vma_iter_set(&vmi, addr);
+	vma_iter_config(&vmi, addr, end);
 	vma->vm_start = addr;
 	vma->vm_end = end;
 	vm_flags_init(vma, vm_flags);
@@ -2686,7 +2686,7 @@ unsigned long mmap_region(struct file *file, unsigned long addr,
 		if (WARN_ON((addr != vma->vm_start)))
 			goto close_and_free_vma;
 
-		vma_iter_set(&vmi, addr);
+		vma_iter_config(&vmi, addr, end);
 		/*
 		 * If vm_flags changed after call_mmap(), we should try merge
 		 * vma again as we may succeed this time.
-- 
2.39.2