linux-kernel - [PATCH] mm/mmap: Introduce unlock

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Date:   Mon, 10 May 2021 19:50:22 +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>,
        Michel Lespinasse <michel@...pinasse.org>,
        Liam Howlett <liam.howlett@...cle.com>
Subject: [PATCH] mm/mmap: Introduce unlock_range() for code cleanup

Both __do_munmap() and exit_mmap() unlock a range of VMAs using almost
identical code blocks.  Replace both blocks by a static inline function.

Signed-off-by: Liam R. Howlett <Liam.Howlett@...cle.com>
---
 mm/mmap.c | 38 +++++++++++++++++++-------------------
 1 file changed, 19 insertions(+), 19 deletions(-)

diff --git a/mm/mmap.c b/mm/mmap.c
index 81f5595a8490..ea556fc795d2 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -2801,6 +2801,21 @@ int split_vma(struct mm_struct *mm, struct vm_area_struct *vma,
 	return __split_vma(mm, vma, addr, new_below);
 }
 
+static inline void unlock_range(struct vm_area_struct *start, unsigned long limit)
+{
+	struct mm_struct *mm = start->vm_mm;
+	struct vm_area_struct *tmp = start;
+
+	while (tmp && tmp->vm_start < limit) {
+		if (tmp->vm_flags & VM_LOCKED) {
+			mm->locked_vm -= vma_pages(tmp);
+			munlock_vma_pages_all(tmp);
+		}
+
+		tmp = tmp->vm_next;
+	}
+}
+
 /* 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.
@@ -2889,17 +2904,8 @@ int __do_munmap(struct mm_struct *mm, unsigned long start, size_t len,
 	/*
 	 * unlock any mlock()ed ranges before detaching vmas
 	 */
-	if (mm->locked_vm) {
-		struct vm_area_struct *tmp = vma;
-		while (tmp && tmp->vm_start < end) {
-			if (tmp->vm_flags & VM_LOCKED) {
-				mm->locked_vm -= vma_pages(tmp);
-				munlock_vma_pages_all(tmp);
-			}
-
-			tmp = tmp->vm_next;
-		}
-	}
+	if (mm->locked_vm)
+		unlock_range(vma, end);
 
 	/* Detach vmas from rbtree */
 	if (!detach_vmas_to_be_unmapped(mm, vma, prev, end))
@@ -3184,14 +3190,8 @@ void exit_mmap(struct mm_struct *mm)
 		mmap_write_unlock(mm);
 	}
 
-	if (mm->locked_vm) {
-		vma = mm->mmap;
-		while (vma) {
-			if (vma->vm_flags & VM_LOCKED)
-				munlock_vma_pages_all(vma);
-			vma = vma->vm_next;
-		}
-	}
+	if (mm->locked_vm)
+		unlock_range(mm->mmap, ULONG_MAX);
 
 	arch_exit_mmap(mm);
 
-- 
2.30.2