From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id EF8A3337BA6 for ; Tue, 3 Mar 2026 10:12:52 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1772532773; cv=none; b=TZl0ZFpmUGZkZDcYHwrKq0uX3wbsljLaxm3aecTzN/9wJ9hQtRQ53hUc41MC3oUd//jef5B16XKqaLLjvEmowCBxAkgB2vOefBVUFDZg0ZZuVF/oeApAI5ETZsNTNej0AYbATWuxtIZRkrisc0avpb/QxWlqlGTltq8V6VOwyEM= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1772532773; c=relaxed/simple; bh=QUoN8n5q5DF0utBmkEV5z51l/ueCTY4b7t6dkFsSAlE=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=Axn31lf1iTjbMX9oPkwoZBaXXV2Ix9Q9rChCaAlmXIVf5Qlo52xcVXB1Q+UPA9k3hNUP4ydDoYLo00HmuNk/cAL6MhaNn+292uBclW/CSB51QWVFCiKXvVPPhZiMcImGUpHtDi0mAI+/teq7MoM9IoWT6E3XDfDJKfcQ00s4JAw= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=p/+SabYa; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="p/+SabYa" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 18BF7C116C6; Tue, 3 Mar 2026 10:12:49 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1772532772; bh=QUoN8n5q5DF0utBmkEV5z51l/ueCTY4b7t6dkFsSAlE=; h=From:To:Cc:Subject:Date:From; b=p/+SabYaHTZfFnOfUY/3odZBn9WemruYkJV2T5ThkK3e0SZwOZZNM+cGmt9yDL0Ne MkRFHkl+ea+dphYiXCnAbKLQs81zJUM2xhml1aHy9M2mXNd9yQ3dV1Dl3mYn+bt44h 9MhI6Th9CLG8YOXmGB4Bpv8VWFnFW+xGdOmwCRwqMzdqCQWvH/J2Ge+Q2kJi7PKhA6 6UTbl62S+sI95Np8TGNQEmQxUaw8vnRhIbvwnQzLbBD6ZnDFrmGqaXjOMpovyuy7iE FmacI4np6IGSpWvRf1UKMk5ehTR6b0ChqF3uTXOFWpXEcbsfOgHYMRb9WRQ137kojv AO5jF4tbZl3GQ== From: "David Hildenbrand (Arm)" To: stable@vger.kernel.org Cc: linux-mm , "David Hildenbrand (Arm)" , Li Ying , Greg Kroah-Hartman , Andrew Morton , Matthew Wilcox , Christoph Lameter , "Liam R . Howlett" Subject: [PATCH 6.6.y] mm/mempolicy: fix wrong mmap_read_unlock() in migrate_to_node() Date: Tue, 3 Mar 2026 11:12:45 +0100 Message-ID: <20260303101245.22290-1-david@kernel.org> X-Mailer: git-send-email 2.43.0 Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit The backport of commit 091c1dd2d4df ("mm/mempolicy: fix migrate_to_node() assuming there is at least one VMA in a MM") contains an error: migrate_to_node() does not lock the mmap_lock itself, that is handled by the caller instead. So let's drop the wrong mmap_read_unlock(). Fortunately, this path is very hard to hit in practice. Fixes: a13b2b9b0b0b ("mm/mempolicy: fix migrate_to_node() assuming there is at least one VMA in a MM") Reported-by: Li Ying Closes: https://lore.kernel.org/r/aaZgUNxAyKC2IwuG@casper.infradead.org Cc: Greg Kroah-Hartman Cc: Andrew Morton Cc: Matthew Wilcox Cc: Christoph Lameter Cc: Liam R. Howlett Cc: Signed-off-by: David Hildenbrand (Arm) --- mm/mempolicy.c | 4 +--- 1 file changed, 1 insertion(+), 3 deletions(-) diff --git a/mm/mempolicy.c b/mm/mempolicy.c index 94c74c594d10..d8007e1c2690 100644 --- a/mm/mempolicy.c +++ b/mm/mempolicy.c @@ -1071,10 +1071,8 @@ static long migrate_to_node(struct mm_struct *mm, int source, int dest, VM_BUG_ON(!(flags & (MPOL_MF_MOVE | MPOL_MF_MOVE_ALL))); vma = find_vma(mm, 0); - if (unlikely(!vma)) { - mmap_read_unlock(mm); + if (unlikely(!vma)) return 0; - } /* * This does not migrate the range, but isolates all pages that -- 2.43.0