From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-lf1-f47.google.com (mail-lf1-f47.google.com [209.85.167.47]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 850607A for ; Fri, 20 May 2022 13:39:34 +0000 (UTC) Received: by mail-lf1-f47.google.com with SMTP id p4so12985632lfg.4 for ; Fri, 20 May 2022 06:39:34 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=shutemov-name.20210112.gappssmtp.com; s=20210112; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:content-transfer-encoding:in-reply-to; bh=3BeEGshpUebf40S3dI2nHaMHUGbrc9YgGRUe6v3NrQI=; b=6qt22nK9IyDROp+1mPdWrxlvzi6NjO9eSG5Nen/b2A4439rifjlgxwQdu1H0oZvaEI zsREZJlUH9Q59JA4/xx902iUi8jdSn8cRb9yxLBKOpTVgUEBc8mktfK/Gl0D93Izd/ul Onz+P2Nvnbw9a32QqyeG9cgY4Z4J9mdF8qFpYKjfy+87PufYse2QuuIZCUVPPDlNvAKE ik5nL2LZ9Bk16e0vHts9nXx0icITt1ybjlmSAmRoFKOj9CpUtY5Q+f5Jk/vtT2A2l3gX tjGCSyXpFudAPCrNP09RJNhINqh3uz45V4pH4Lmn9DWgW4Uk7j2mupibV5+qfh9CEpti MVrQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:content-transfer-encoding :in-reply-to; bh=3BeEGshpUebf40S3dI2nHaMHUGbrc9YgGRUe6v3NrQI=; b=TdGv5T9Fv3Ij0LeJe4f3CY8ku+S2Uvyu5rRKR6SW/Ps5pEBJzMRRovD9uBS/TxbtAN pBkJcMatoEwprLFxzW8De9lpQFsThBYmS64PmhlfT5rRBYbDzWnc7CxSIMFvFj/ge/+Z 6Y389eaqLj6VMGW6PQeg0SeT081tOjyjUPXczug2trJdpi6DH3imOld4qn/XXiIbXv+f 0EhdNX/B1M/fMsI+FMUd7TVFiDvG+fmjsQUMMqTd45Wf2GNCH+jPp2SnD2WHeT60aQyd c01Epdkv7xtxfpCcgTQyLoOTYtt/YpRITCJQnd6sV6sUROHXOdBMrM8lO0GAaG35awc0 5b2A== X-Gm-Message-State: AOAM531A/n+uZAu2EFv/Ui8IUbeZOSFvJTlSKVaZNWixclVF2TWje/FV rCID+9rjaxeNn4IGCyqPwedNFw== X-Google-Smtp-Source: ABdhPJyT1m9j6Hn8ES8585uw0TDj+nJSjxY8pFZYdW/m0XbSSumm094xJFwQQSPevh3hEaAT3pcheQ== X-Received: by 2002:a19:4f04:0:b0:477:b6c7:9771 with SMTP id d4-20020a194f04000000b00477b6c79771mr6778897lfb.182.1653053972054; Fri, 20 May 2022 06:39:32 -0700 (PDT) Received: from box.localdomain ([86.57.175.117]) by smtp.gmail.com with ESMTPSA id e7-20020a2e9847000000b0024f3d1daeacsm323659ljj.52.2022.05.20.06.39.31 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 20 May 2022 06:39:31 -0700 (PDT) Received: by box.localdomain (Postfix, from userid 1000) id C70E6104AAB; Fri, 20 May 2022 16:41:24 +0300 (+03) Date: Fri, 20 May 2022 16:41:24 +0300 From: "Kirill A. Shutemov" To: Jakub =?utf-8?Q?Mat=C4=9Bna?= Cc: linux-mm@kvack.org, patches@lists.linux.dev, linux-kernel@vger.kernel.org, vbabka@suse.cz, mhocko@kernel.org, mgorman@techsingularity.net, willy@infradead.org, liam.howlett@oracle.com, hughd@google.com, riel@surriel.com, rostedt@goodmis.org, peterz@infradead.org, david@redhat.com Subject: Re: [RFC PATCH v3 2/6] [PATCH 2/6] mm: add merging after mremap resize Message-ID: <20220520134124.6glbfzhrgzutfor6@box.shutemov.name> References: <20220516125405.1675-1-matenajakub@gmail.com> <20220516125405.1675-3-matenajakub@gmail.com> Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20220516125405.1675-3-matenajakub@gmail.com> On Mon, May 16, 2022 at 02:54:01PM +0200, Jakub Matěna wrote: > When mremap call results in expansion, it might be possible to merge the > VMA with the next VMA which might become adjacent. This patch adds > vma_merge call after the expansion is done to try and merge. > > Signed-off-by: Jakub Matěna > --- > mm/mremap.c | 7 +++++-- > 1 file changed, 5 insertions(+), 2 deletions(-) > > diff --git a/mm/mremap.c b/mm/mremap.c > index 303d3290b938..75cda854ec58 100644 > --- a/mm/mremap.c > +++ b/mm/mremap.c > @@ -9,6 +9,7 @@ > */ > > #include > +#include > #include > #include > #include > @@ -1022,8 +1023,10 @@ SYSCALL_DEFINE5(mremap, unsigned long, addr, unsigned long, old_len, > } > } > > - if (vma_adjust(vma, vma->vm_start, addr + new_len, > - vma->vm_pgoff, NULL)) { > + if (!vma_merge(mm, vma, addr + old_len, addr + new_len, > + vma->vm_flags, vma->anon_vma, vma->vm_file, > + vma->vm_pgoff + (old_len >> PAGE_SHIFT), vma_policy(vma), > + vma->vm_userfaultfd_ctx, anon_vma_name(vma))) { Hm. Don't you need to update 'vma' with result of vma_merge()? 'vma' is used below the point and IIUC it can be use-after-free. -- Kirill A. Shutemov