From nobody Sat Feb 7 18:15:21 2026 Received: from out-170.mta0.migadu.com (out-170.mta0.migadu.com [91.218.175.170]) (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 E545D1078D for ; Sun, 18 Feb 2024 08:50:44 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=91.218.175.170 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1708246247; cv=none; b=YAmxivRZG1IEHB8f+tJbCdhq5NAMAMJtnyUd1cKUOpaZU/ELZPzSZW2Mh8kafCshdFC8RGJpZ+PZFMtqdvjCh1paetTiXMBPXdRUsR3hid0DwV7U0dUdJk1XDBOH2Pll6or/XX1uHZxv1qUnIP/PM1t3DDf5z4k7SB6CQ/PWEzY= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1708246247; c=relaxed/simple; bh=da1qu/r9stegXEm7ynAOlKBK2eKOnZ0EjDNsWTT4L0I=; h=From:To:Cc:Subject:Date:Message-Id:MIME-Version; b=nqKjWeMY8G1zpfnncisEcf56o1DkGOZnO2JSzTsK6kFnXt/NFlDHxJlbJG0QMZ1E3tSEAqpV8HDtVrXImqELxvWG4BcIMoimFajaf0oL4Zs0nxvYI0jp4dEz5+d9A975CJRAcLXWZmAvIFMhjnJh4FEUePU1yKLIA5loh21ejZ4= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev; spf=pass smtp.mailfrom=linux.dev; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b=Njlk1OD0; arc=none smtp.client-ip=91.218.175.170 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.dev Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b="Njlk1OD0" X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1708246243; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding; bh=AEljPih4VKEaedgdPxkR+QTAZVEHkgRl9SR5WXdN/js=; b=Njlk1OD0qYqxPkPOtxILtH6gC5FBCH55YfGbAwkVLzJv8DOR3Afi5Gl7doigiVCmVeWQ3i N92VXe+rl6TPn+I812AtuNGuFjL7llLIT/VEShOm7xQflwemEO3qeOwjGLdYTZV+AvmslC uYlKLV/sbWIRfdvhSWn6dX2snC8m69c= From: Yajun Deng To: akpm@linux-foundation.org Cc: Liam.Howlett@Oracle.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org, Yajun Deng Subject: [PATCH] mm/mmap: Add case 9 in vma_merge() Date: Sun, 18 Feb 2024 16:50:28 +0800 Message-Id: <20240218085028.3294332-1-yajun.deng@linux.dev> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-Migadu-Flow: FLOW_OUT Content-Type: text/plain; charset="utf-8" If the prev vma exists and the end is less than the end of prev, we can return NULL immediately. This reduces unnecessary operations. Signed-off-by: Yajun Deng --- mm/mmap.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) diff --git a/mm/mmap.c b/mm/mmap.c index 8f176027583c..b738849321c0 100644 --- a/mm/mmap.c +++ b/mm/mmap.c @@ -827,7 +827,7 @@ can_vma_merge_after(struct vm_area_struct *vma, unsigne= d long vm_flags, * * **** **** **** * PPPPPPNNNNNN PPPPPPNNNNNN PPPPPPCCCCCC - * cannot merge might become might become + * cannot merge 9 might become might become * PPNNNNNNNNNN PPPPPPPPPPCC * mmap, brk or case 4 below case 5 below * mremap move: @@ -890,6 +890,9 @@ static struct vm_area_struct if (vm_flags & VM_SPECIAL) return NULL; =20 + if (prev && end < prev->vm_end) /* case 9 */ + return NULL; + /* Does the input range span an existing VMA? (cases 5 - 8) */ curr =3D find_vma_intersection(mm, prev ? prev->vm_end : 0, end); =20 --=20 2.25.1