From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id CE0A9CD612F for ; Mon, 9 Oct 2023 20:54:06 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1378152AbjJIUyE (ORCPT ); Mon, 9 Oct 2023 16:54:04 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:57248 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1378147AbjJIUxw (ORCPT ); Mon, 9 Oct 2023 16:53:52 -0400 Received: from mail-wr1-x433.google.com (mail-wr1-x433.google.com [IPv6:2a00:1450:4864:20::433]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id BF3C5B0; Mon, 9 Oct 2023 13:53:41 -0700 (PDT) Received: by mail-wr1-x433.google.com with SMTP id ffacd0b85a97d-32615eaa312so4575814f8f.2; Mon, 09 Oct 2023 13:53:41 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1696884820; x=1697489620; darn=vger.kernel.org; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:from:to:cc:subject:date :message-id:reply-to; bh=xL574zJuwTg3rbZ38h4Jjm16YvUMoLxu5gzcSq0qQog=; b=dbvlfFcWXQ6iaB0eGPBARCf/16J/NcSoekYzPmQFSHACh24Ne6J1eUMT6riokp5eI3 V1nxGfackS0KshmDqeA7WXLJymGtoCeibTAFKbtyH10tvwKQ/HCLeOL4AWnIbxPcBblG Taw4E+9JFCGwfZLb0q8WhHlNG/mjCYikIKFlVSvfF9W5hS2QWEVBfdLxsLxPrWndvNb7 kQrGcJZqBB8AUq4Wv9QIVigTnj47zAuZTOuW+mxYN/gd0d1rmitBzhu15HD5TZSzZ5r/ To3bFKEFC2HrOt44+82Y8DpwhnCsxGvnVmC9hcMfk3CW2n7deOhIx10p3Z77clA29qTj SL6g== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1696884820; x=1697489620; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=xL574zJuwTg3rbZ38h4Jjm16YvUMoLxu5gzcSq0qQog=; b=ZLvcBRKOV/rIzdD5yJrae6biTqwdVPddd7sILpe0ULT8H3vpytj4E5WVa1euHEnwxz pjF3lA2tU9uQ+k4EEvSwHCNj19M5tH9FqfZMrvE2fm8MyILeNSTS2iZS7/B4N25ZvvVH e2shW6KgFPdV6Ztbs+/tu/NlEkNjXSMqa5LGEB8RCHkVZBhxa20vuTtpc3lV/yclZ+2M iiRTgcXouF4n63jNy5V8c5WOwucyeis63LMm4WXm8v6xdIFQ8EmqTNOBJoQLP2t7K2zi n/GiWnkPW/hlX+1Qi53LH/WhJLf2riFwhhbY4r6n7lQ1DiZJ3WNCrrPQ1ZxfZ8MCGaRD FBig== X-Gm-Message-State: AOJu0YzUhFWGME0DFoDxEUV60/EzNdfGLhs4noE0STBg88zl8yxrdMs4 SzG/ctxX3bfExWMatNUkVivT6iiQPsg= X-Google-Smtp-Source: AGHT+IEZcDJXfUk/m4asVym6HC8MzhKstd/QCfQCxF3CdaRPkCYRP2UAGVNJPPmMrmT3c3m/Jt2IXw== X-Received: by 2002:adf:e6ce:0:b0:31f:b7b2:d4e1 with SMTP id y14-20020adfe6ce000000b0031fb7b2d4e1mr14332666wrm.20.1696884819954; Mon, 09 Oct 2023 13:53:39 -0700 (PDT) Received: from lucifer.home ([2a00:23c5:dc8c:8701:1663:9a35:5a7b:1d76]) by smtp.googlemail.com with ESMTPSA id l2-20020a5d4802000000b0031fe0576460sm10578130wrq.11.2023.10.09.13.53.38 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 09 Oct 2023 13:53:39 -0700 (PDT) From: Lorenzo Stoakes To: linux-mm@kvack.org, linux-kernel@vger.kernel.org, Andrew Morton , Alexander Viro , Christian Brauner Cc: "=Liam R . Howlett" , Vlastimil Babka , linux-fsdevel@vger.kernel.org, Lorenzo Stoakes Subject: [PATCH v2 5/5] mm: abstract VMA merge and extend into vma_merge_extend() helper Date: Mon, 9 Oct 2023 21:53:20 +0100 Message-ID: X-Mailer: git-send-email 2.42.0 In-Reply-To: References: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org mremap uses vma_merge() in the case where a VMA needs to be extended. This can be significantly simplified and abstracted. This makes it far easier to understand what the actual function is doing, avoids future mistakes in use of the confusing vma_merge() function and importantly allows us to make future changes to how vma_merge() is implemented by knowing explicitly which merge cases each invocation uses. Note that in the mremap() extend case, we perform this merge only when old_len == vma->vm_end - addr. The extension_start, i.e. the start of the extended portion of the VMA is equal to addr + old_len, i.e. vma->vm_end. With this refactoring, vma_merge() is no longer required anywhere except mm/mmap.c, so mark it static. Reviewed-by: Vlastimil Babka Signed-off-by: Lorenzo Stoakes --- mm/internal.h | 8 +++----- mm/mmap.c | 31 ++++++++++++++++++++++++------- mm/mremap.c | 30 +++++++++++++----------------- 3 files changed, 40 insertions(+), 29 deletions(-) diff --git a/mm/internal.h b/mm/internal.h index ddaeb9f2d9d7..6fa722b07a94 100644 --- a/mm/internal.h +++ b/mm/internal.h @@ -1014,11 +1014,9 @@ struct page *follow_trans_huge_pmd(struct vm_area_struct *vma, /* * mm/mmap.c */ -struct vm_area_struct *vma_merge(struct vma_iterator *vmi, - struct mm_struct *, struct vm_area_struct *prev, unsigned long addr, - unsigned long end, unsigned long vm_flags, struct anon_vma *, - struct file *, pgoff_t, struct mempolicy *, struct vm_userfaultfd_ctx, - struct anon_vma_name *); +struct vm_area_struct *vma_merge_extend(struct vma_iterator *vmi, + struct vm_area_struct *vma, + unsigned long delta); enum { /* mark page accessed */ diff --git a/mm/mmap.c b/mm/mmap.c index 33aafd23823b..200319bf3292 100644 --- a/mm/mmap.c +++ b/mm/mmap.c @@ -860,13 +860,13 @@ can_vma_merge_after(struct vm_area_struct *vma, unsigned long vm_flags, * **** is not represented - it will be merged and the vma containing the * area is returned, or the function will return NULL */ -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, - struct vm_userfaultfd_ctx vm_userfaultfd_ctx, - struct anon_vma_name *anon_name) +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, + struct vm_userfaultfd_ctx vm_userfaultfd_ctx, + struct anon_vma_name *anon_name) { struct vm_area_struct *curr, *next, *res; struct vm_area_struct *vma, *adjust, *remove, *remove2; @@ -2498,6 +2498,23 @@ static struct vm_area_struct *vma_merge_new_vma(struct vma_iterator *vmi, vma->vm_userfaultfd_ctx, anon_vma_name(vma)); } +/* + * Expand vma by delta bytes, potentially merging with an immediately adjacent + * VMA with identical properties. + */ +struct vm_area_struct *vma_merge_extend(struct vma_iterator *vmi, + struct vm_area_struct *vma, + unsigned long delta) +{ + pgoff_t pgoff = vma->vm_pgoff + vma_pages(vma); + + /* 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)); +} + /* * do_vmi_align_munmap() - munmap the aligned region from @start to @end. * @vmi: The vma iterator diff --git a/mm/mremap.c b/mm/mremap.c index ce8a23ef325a..38d98465f3d8 100644 --- a/mm/mremap.c +++ b/mm/mremap.c @@ -1096,14 +1096,12 @@ SYSCALL_DEFINE5(mremap, unsigned long, addr, unsigned long, old_len, /* old_len exactly to the end of the area.. */ if (old_len == vma->vm_end - addr) { + unsigned long delta = new_len - old_len; + /* can we just expand the current mapping? */ - if (vma_expandable(vma, new_len - old_len)) { - long pages = (new_len - old_len) >> PAGE_SHIFT; - unsigned long extension_start = addr + old_len; - unsigned long extension_end = addr + new_len; - pgoff_t extension_pgoff = vma->vm_pgoff + - ((extension_start - vma->vm_start) >> PAGE_SHIFT); - VMA_ITERATOR(vmi, mm, extension_start); + if (vma_expandable(vma, delta)) { + long pages = delta >> PAGE_SHIFT; + VMA_ITERATOR(vmi, mm, vma->vm_end); long charged = 0; if (vma->vm_flags & VM_ACCOUNT) { @@ -1115,17 +1113,15 @@ SYSCALL_DEFINE5(mremap, unsigned long, addr, unsigned long, old_len, } /* - * Function vma_merge() is called on the extension we - * are adding to the already existing vma, vma_merge() - * will merge this extension with the already existing - * vma (expand operation itself) and possibly also with - * the next vma if it becomes adjacent to the expanded - * vma and otherwise compatible. + * Function vma_merge_extend() is called on the + * extension we are adding to the already existing vma, + * vma_merge_extend() will merge this extension with the + * already existing vma (expand operation itself) and + * possibly also with the next vma if it becomes + * adjacent to the expanded vma and otherwise + * compatible. */ - vma = vma_merge(&vmi, mm, vma, extension_start, - extension_end, vma->vm_flags, vma->anon_vma, - vma->vm_file, extension_pgoff, vma_policy(vma), - vma->vm_userfaultfd_ctx, anon_vma_name(vma)); + vma = vma_merge_extend(&vmi, vma, delta); if (!vma) { vm_unacct_memory(charged); ret = -ENOMEM; -- 2.42.0