linux-kernel - [PATCH v5 08/21] mm/mmap: Inline munmap operation in mmap

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Message-ID: <20240717200709.1552558-9-Liam.Howlett@oracle.com>
Date: Wed, 17 Jul 2024 16:06:56 -0400
From: "Liam R. Howlett" <Liam.Howlett@...cle.com>
To: linux-mm@...ck.org, Andrew Morton <akpm@...ux-foundation.org>
Cc: Suren Baghdasaryan <surenb@...gle.com>, Vlastimil Babka <vbabka@...e.cz>,
        Lorenzo Stoakes <lstoakes@...il.com>,
        Matthew Wilcox <willy@...radead.org>, sidhartha.kumar@...cle.com,
        "Paul E . McKenney" <paulmck@...nel.org>,
        Bert Karwatzki <spasswolf@....de>, Jiri Olsa <olsajiri@...il.com>,
        linux-kernel@...r.kernel.org, Kees Cook <kees@...nel.org>,
        Jeff Xu <jeffxu@...omium.org>,
        "Liam R. Howlett" <Liam.Howlett@...cle.com>,
        Lorenzo Stoakes <lorenzo.stoakes@...cle.com>
Subject: [PATCH v5 08/21] mm/mmap: Inline munmap operation in mmap_region()

From: "Liam R. Howlett" <Liam.Howlett@...cle.com>

mmap_region is already passed sanitized addr and len, so change the
call to do_vmi_munmap() to do_vmi_align_munmap() and inline the other
checks.

The inlining of the function and checks is an intermediate step in the
series so future patches are easier to follow.

Signed-off-by: Liam R. Howlett <Liam.Howlett@...cle.com>
Reviewed-by: Lorenzo Stoakes <lorenzo.stoakes@...cle.com>
---
 mm/mmap.c | 21 +++++++++++++++------
 1 file changed, 15 insertions(+), 6 deletions(-)

diff --git a/mm/mmap.c b/mm/mmap.c
index 1c9016fb6b5c..49b3ab406353 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -2938,12 +2938,21 @@ unsigned long mmap_region(struct file *file, unsigned long addr,
 			return -ENOMEM;
 	}
 
-	/* Unmap any existing mapping in the area */
-	error = do_vmi_munmap(&vmi, mm, addr, len, uf, false);
-	if (error == -EPERM)
-		return error;
-	else if (error)
-		return -ENOMEM;
+
+	if (unlikely(!can_modify_mm(mm, addr, end)))
+		return -EPERM;
+
+	 /* arch_unmap() might do unmaps itself.  */
+	arch_unmap(mm, addr, end);
+
+	/* Find the first overlapping VMA */
+	vma = vma_find(&vmi, end);
+	if (vma) {
+		/* Unmap any existing mapping in the area */
+		if (do_vmi_align_munmap(&vmi, vma, mm, addr, end, uf, false))
+			return -ENOMEM;
+		vma = NULL;
+	}
 
 	/*
 	 * Private writable mapping: check memory availability
-- 
2.43.0