linux-kernel - [PATCH v2 4/4] mm, madvise: use standard madvise locking in madvise_set_anon

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Message-Id: <20250624-anon_name_cleanup-v2-4-600075462a11@suse.cz>
Date: Tue, 24 Jun 2025 15:03:48 +0200
From: Vlastimil Babka <vbabka@...e.cz>
To: Andrew Morton <akpm@...ux-foundation.org>, 
 "Liam R. Howlett" <Liam.Howlett@...cle.com>, 
 Lorenzo Stoakes <lorenzo.stoakes@...cle.com>, 
 David Hildenbrand <david@...hat.com>, Jann Horn <jannh@...gle.com>, 
 Mike Rapoport <rppt@...nel.org>, Suren Baghdasaryan <surenb@...gle.com>, 
 Michal Hocko <mhocko@...e.com>, Colin Cross <ccross@...gle.com>
Cc: linux-mm@...ck.org, linux-kernel@...r.kernel.org, 
 Vlastimil Babka <vbabka@...e.cz>
Subject: [PATCH v2 4/4] mm, madvise: use standard madvise locking in
 madvise_set_anon_name()

Use madvise_lock()/madvise_unlock() in madvise_set_anon_name() in the
same way as in do_madvise(). This narrows the lock scope a bit and
reuses existing functionality. get_lock_mode() already picks the correct
MADVISE_MMAP_WRITE_LOCK mode for __MADV_SET_ANON_VMA_NAME so we can just
remove the explicit assignment.

Signed-off-by: Vlastimil Babka <vbabka@...e.cz>
---
 mm/madvise.c | 13 +++++++++----
 1 file changed, 9 insertions(+), 4 deletions(-)

diff --git a/mm/madvise.c b/mm/madvise.c
index cae064479cdf908707c45b941bd03d43d095eab6..ee02ccd0315a146cdb3001cd189e03be9e48a2ea 100644
--- a/mm/madvise.c
+++ b/mm/madvise.c
@@ -2082,10 +2082,10 @@ static int madvise_set_anon_name(struct mm_struct *mm, unsigned long start,
 {
 	unsigned long end;
 	unsigned long len;
+	int error;
 	struct madvise_behavior madv_behavior = {
 		.mm = mm,
 		.behavior = __MADV_SET_ANON_VMA_NAME,
-		.lock_mode = MADVISE_MMAP_WRITE_LOCK,
 		.anon_name = anon_name,
 	};

@@ -2106,7 +2106,14 @@ static int madvise_set_anon_name(struct mm_struct *mm, unsigned long start,

 	madv_behavior.range.start = start;
 	madv_behavior.range.end = end;
-	return madvise_walk_vmas(&madv_behavior);
+
+	error = madvise_lock(&madv_behavior);
+	if (error)
+		return error;
+	error = madvise_walk_vmas(&madv_behavior);
+	madvise_unlock(&madv_behavior);
+
+	return error;
 }

 int set_anon_vma_name(unsigned long addr, unsigned long size,
@@ -2136,9 +2143,7 @@ int set_anon_vma_name(unsigned long addr, unsigned long size,
 			return -ENOMEM;
 	}

-	mmap_write_lock(mm);
 	error = madvise_set_anon_name(mm, addr, size, anon_name);
-	mmap_write_unlock(mm);
 	anon_vma_name_put(anon_name);

 	return error;

-- 
2.50.0