From nobody Thu Dec 25 08:43:42 2025 Received: from out-172.mta1.migadu.com (out-172.mta1.migadu.com [95.215.58.172]) (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 74A6B125D3 for ; Thu, 18 Jan 2024 08:23:29 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=95.215.58.172 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1705566212; cv=none; b=qbb0F37vXUzmJ1ffBLmYwPr09KqmLQPTrySA0943c4SwzXoLp62+jSqEeK+yUqo10Cf8CiMe36WcT7a+PFpWIRL23JJ1qtdB/MZEAhgqLqxf6+6k0u1iSah3kO/7lUNjS2BPpUJoPQTmFWVPC8TssashPq6VDsSeLpSAp/xu5Ew= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1705566212; c=relaxed/simple; bh=C1hmTg2nY8yzj64atwww1ythwPSEs6LPcdpJP7PXbqw=; h=X-Report-Abuse:DKIM-Signature:From:To:Cc:Subject:Date:Message-Id: MIME-Version:Content-Transfer-Encoding:X-Migadu-Flow; b=lvq8xIWl17YDyvzX0m/xdOhZoWPGcU3Q945U6/+rsxnfgDGzNbqmJawMujlCaoMn1G6sQApR8DmAhhlyprb8vUc+B99JqdPoiht1cB0gEQ7vhON0kOYtRPnXTiDCMUldFgLqS+aQI2dp5Dstiq9XjwLeW146yh2er5Nu4RogShA= 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=SBJmTn8g; arc=none smtp.client-ip=95.215.58.172 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="SBJmTn8g" 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=1705566207; 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=pe8IQrETqG5sJ0hFhkc64W1l6+nAKA4aDlhTJnXDWtk=; b=SBJmTn8g80S8xKAdpZWPh/c8KSATg87T78tr6m5D14ECkBeTJqRCJfnqu63LsoU1CU2t5Z BaoXLQyzx9nI+IezmXxYukd1V73FEBZ7GsBUFrrd+FiExJjqTVjDwno93GRTNj7/WVhpRI nSv3+o86VTpwX8+wlHsxW+SIEqRopps= From: Yajun Deng To: akpm@linux-foundation.org Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, Yajun Deng Subject: [PATCH] mm/mmap: simplify vma_merge() Date: Thu, 18 Jan 2024 16:23:12 +0800 Message-Id: <20240118082312.2801992-1-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" These vma_merge() callers will pass mm, anon_vma and file, they all from vma. There is no need to pass three parameters at the same time. We will find the current vma in vma_merge(). If we pass the original vma to vma_merge(), the current vma is actually the original vma or NULL. So we didn't need to find the current vma with find_vma_intersection(). Pass vma to vma_merge(), and add a check to make sure the current vma is an existing vma. Signed-off-by: Yajun Deng --- mm/mmap.c | 37 +++++++++++++++++-------------------- 1 file changed, 17 insertions(+), 20 deletions(-) diff --git a/mm/mmap.c b/mm/mmap.c index 49d25172eac8..7e00ae4f39e3 100644 --- a/mm/mmap.c +++ b/mm/mmap.c @@ -860,14 +860,16 @@ can_vma_merge_after(struct vm_area_struct *vma, unsig= ned long vm_flags, * area is returned, or the function will return NULL */ static struct vm_area_struct -*vma_merge(struct vma_iterator *vmi, struct mm_struct *mm, - struct vm_area_struct *prev, unsigned long addr, unsigned long end, - unsigned long vm_flags, struct anon_vma *anon_vma, struct file *file, - pgoff_t pgoff, struct mempolicy *policy, +*vma_merge(struct vma_iterator *vmi, struct vm_area_struct *prev, + struct vm_area_struct *curr, unsigned long addr, unsigned long end, + unsigned long vm_flags, pgoff_t pgoff, struct mempolicy *policy, struct vm_userfaultfd_ctx vm_userfaultfd_ctx, struct anon_vma_name *anon_name) { - struct vm_area_struct *curr, *next, *res; + struct mm_struct *mm =3D curr->vm_mm; + struct anon_vma *anon_vma =3D curr->anon_vma; + struct file *file =3D curr->vm_file; + struct vm_area_struct *next =3D NULL, *res; struct vm_area_struct *vma, *adjust, *remove, *remove2; struct vm_area_struct *anon_dup =3D NULL; struct vma_prepare vp; @@ -889,13 +891,12 @@ static struct vm_area_struct return NULL; =20 /* Does the input range span an existing VMA? (cases 5 - 8) */ - curr =3D find_vma_intersection(mm, prev ? prev->vm_end : 0, end); + if (prev =3D=3D curr || addr !=3D curr->vm_start || end > curr->vm_end) + curr =3D NULL; =20 if (!curr || /* cases 1 - 4 */ end =3D=3D curr->vm_end) /* cases 6 - 8, adjacent VMA */ - next =3D vma_lookup(mm, end); - else - next =3D NULL; /* case 5 */ + next =3D vma_lookup(mm, end); /* NULL case 5 */ =20 if (prev) { vma_start =3D prev->vm_start; @@ -919,7 +920,6 @@ static struct vm_area_struct =20 /* Verify some invariant that must be enforced by the caller. */ VM_WARN_ON(prev && addr <=3D prev->vm_start); - VM_WARN_ON(curr && (addr !=3D curr->vm_start || end > curr->vm_end)); VM_WARN_ON(addr >=3D end); =20 if (!merge_prev && !merge_next) @@ -2424,9 +2424,8 @@ struct vm_area_struct *vma_modify(struct vma_iterator= *vmi, pgoff_t pgoff =3D vma->vm_pgoff + ((start - vma->vm_start) >> PAGE_SHIFT); struct vm_area_struct *merged; =20 - merged =3D vma_merge(vmi, vma->vm_mm, prev, start, end, vm_flags, - vma->anon_vma, vma->vm_file, pgoff, policy, - uffd_ctx, anon_name); + merged =3D vma_merge(vmi, prev, vma, start, end, vm_flags, + pgoff, policy, uffd_ctx, anon_name); if (merged) return merged; =20 @@ -2456,9 +2455,8 @@ static struct vm_area_struct struct vm_area_struct *vma, unsigned long start, unsigned long end, pgoff_t pgoff) { - return vma_merge(vmi, vma->vm_mm, prev, start, end, vma->vm_flags, - vma->anon_vma, vma->vm_file, pgoff, vma_policy(vma), - vma->vm_userfaultfd_ctx, anon_vma_name(vma)); + return vma_merge(vmi, prev, vma, start, end, vma->vm_flags, pgoff, + vma_policy(vma), vma->vm_userfaultfd_ctx, anon_vma_name(vma)); } =20 /* @@ -2472,10 +2470,9 @@ struct vm_area_struct *vma_merge_extend(struct vma_i= terator *vmi, pgoff_t pgoff =3D vma->vm_pgoff + vma_pages(vma); =20 /* vma is specified as prev, so case 1 or 2 will apply. */ - return vma_merge(vmi, vma->vm_mm, vma, vma->vm_end, vma->vm_end + delta, - vma->vm_flags, vma->anon_vma, vma->vm_file, pgoff, - vma_policy(vma), vma->vm_userfaultfd_ctx, - anon_vma_name(vma)); + return vma_merge(vmi, vma, vma, vma->vm_end, vma->vm_end + delta, + vma->vm_flags, pgoff, vma_policy(vma), + vma->vm_userfaultfd_ctx, anon_vma_name(vma)); } =20 /* --=20 2.25.1