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 X-Spam-Level: X-Spam-Status: No, score=-15.4 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_SANE_1 autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 2B131C433DB for ; Wed, 3 Feb 2021 01:27:19 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 9093064E3D for ; Wed, 3 Feb 2021 01:27:18 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 9093064E3D Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=huawei.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 07E746B006E; Tue, 2 Feb 2021 20:27:18 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 008346B0070; Tue, 2 Feb 2021 20:27:17 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id DEBC06B0071; Tue, 2 Feb 2021 20:27:17 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0120.hostedemail.com [216.40.44.120]) by kanga.kvack.org (Postfix) with ESMTP id C52E66B006E for ; Tue, 2 Feb 2021 20:27:17 -0500 (EST) Received: from smtpin14.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay02.hostedemail.com (Postfix) with ESMTP id 8E1623635 for ; Wed, 3 Feb 2021 01:27:17 +0000 (UTC) X-FDA: 77775218514.14.AB32B2F Received: from szxga05-in.huawei.com (szxga05-in.huawei.com [45.249.212.191]) by imf08.hostedemail.com (Postfix) with ESMTP id E6A9B80191E9 for ; Wed, 3 Feb 2021 01:27:14 +0000 (UTC) Received: from DGGEMS410-HUB.china.huawei.com (unknown [172.30.72.59]) by szxga05-in.huawei.com (SkyGuard) with ESMTP id 4DVkWv5tQ5zMTrn; Wed, 3 Feb 2021 09:25:31 +0800 (CST) Received: from [10.174.179.241] (10.174.179.241) by DGGEMS410-HUB.china.huawei.com (10.3.19.210) with Microsoft SMTP Server id 14.3.498.0; Wed, 3 Feb 2021 09:27:05 +0800 Subject: Re: [PATCH 1/2] mm: replace BUG_ON in vm_insert_page with a return of an error To: Suren Baghdasaryan , CC: , , , , , , , , , , , , , , , , , , , References: <20210203003134.2422308-1-surenb@google.com> From: Miaohe Lin Message-ID: Date: Wed, 3 Feb 2021 09:27:04 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:78.0) Gecko/20100101 Thunderbird/78.6.0 MIME-Version: 1.0 In-Reply-To: <20210203003134.2422308-1-surenb@google.com> Content-Type: text/plain; charset="utf-8" Content-Language: en-US Content-Transfer-Encoding: 7bit X-Originating-IP: [10.174.179.241] X-CFilter-Loop: Reflected X-Stat-Signature: r5bzapdpmfwog1meb5um81soj5n9b63p X-Rspamd-Server: rspam02 X-Rspamd-Queue-Id: E6A9B80191E9 Received-SPF: none (huawei.com>: No applicable sender policy available) receiver=imf08; identity=mailfrom; envelope-from=""; helo=szxga05-in.huawei.com; client-ip=45.249.212.191 X-HE-DKIM-Result: none/none X-HE-Tag: 1612315634-977412 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: Hi: On 2021/2/3 8:31, Suren Baghdasaryan wrote: > Replace BUG_ON(vma->vm_flags & VM_PFNMAP) in vm_insert_page with > WARN_ON_ONCE and returning an error. This is to ensure users of the > vm_insert_page that set VM_PFNMAP are notified of the wrong flag usage > and get an indication of an error without panicing the kernel. > This will help identifying drivers that need to clear VM_PFNMAP before > using dmabuf system heap which is moving to use vm_insert_page. > > Suggested-by: Christoph Hellwig > Signed-off-by: Suren Baghdasaryan Looks reasonable. Thanks. Reviewed-by: Miaohe Lin > --- > mm/memory.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > diff --git a/mm/memory.c b/mm/memory.c > index feff48e1465a..e503c9801cd9 100644 > --- a/mm/memory.c > +++ b/mm/memory.c > @@ -1827,7 +1827,8 @@ int vm_insert_page(struct vm_area_struct *vma, unsigned long addr, > return -EINVAL; > if (!(vma->vm_flags & VM_MIXEDMAP)) { > BUG_ON(mmap_read_trylock(vma->vm_mm)); > - BUG_ON(vma->vm_flags & VM_PFNMAP); > + if (WARN_ON_ONCE(vma->vm_flags & VM_PFNMAP)) > + return -EINVAL; > vma->vm_flags |= VM_MIXEDMAP; > } > return insert_page(vma, addr, page, vma->vm_page_prot); >