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=-10.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS 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 98D1BC4707F for ; Wed, 26 May 2021 03:04:35 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 1676C61429 for ; Wed, 26 May 2021 03:04:35 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 1676C61429 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=linux-foundation.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 9C5546B007E; Tue, 25 May 2021 23:04:34 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 94D696B0081; Tue, 25 May 2021 23:04:34 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 7C7D06B0082; Tue, 25 May 2021 23:04:34 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0108.hostedemail.com [216.40.44.108]) by kanga.kvack.org (Postfix) with ESMTP id 451DA6B007E for ; Tue, 25 May 2021 23:04:34 -0400 (EDT) Received: from smtpin08.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay03.hostedemail.com (Postfix) with ESMTP id D4A988249980 for ; Wed, 26 May 2021 03:04:33 +0000 (UTC) X-FDA: 78181889226.08.10752D5 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by imf07.hostedemail.com (Postfix) with ESMTP id 5181AA0001C0 for ; Wed, 26 May 2021 03:04:26 +0000 (UTC) Received: by mail.kernel.org (Postfix) with ESMTPSA id 323BE61059; Wed, 26 May 2021 03:04:32 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1621998272; bh=V4OpdXOQ49FmWgr/xUUxYOmoUsWXjcuopfW08hMrjv8=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=kSfWwaZ/I/MUjqP8ClC5NFBBhtbtwTtUV5fuaH+f597H5ZPRBtKz5JzjREaFInqZN FF4Kp0lT5LeFOBHGqlx8A6hjo0/JRkSpISjVFlOo2PsY5bfR57DXmbJt/Ngf/fyA/H YBq8GQ0THZbtXlJib70TNVVst5pdpdbC8jp65eTQ= Date: Tue, 25 May 2021 20:04:31 -0700 From: Andrew Morton To: Peter Xu Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, Mike Kravetz , Mike Rapoport , Axel Rasmussen , Andrea Arcangeli , Hugh Dickins , "Kirill A . Shutemov" , Jerome Glisse Subject: Re: [PATCH 2/6] mm/userfaultfd: Fix uffd-wp special cases for fork() Message-Id: <20210525200431.41eb48106ba681151f320afb@linux-foundation.org> In-Reply-To: References: <20210428225030.9708-1-peterx@redhat.com> <20210428225030.9708-3-peterx@redhat.com> <20210525171558.3b223a89c16bdf002f3e83cf@linux-foundation.org> X-Mailer: Sylpheed 3.5.1 (GTK+ 2.24.31; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Authentication-Results: imf07.hostedemail.com; dkim=pass header.d=linux-foundation.org header.s=korg header.b="kSfWwaZ/"; dmarc=none; spf=pass (imf07.hostedemail.com: domain of akpm@linux-foundation.org designates 198.145.29.99 as permitted sender) smtp.mailfrom=akpm@linux-foundation.org X-Rspamd-Server: rspam05 X-Rspamd-Queue-Id: 5181AA0001C0 X-Stat-Signature: jupeh1xwarhzxeu4rctqqwr3q7kya8cx X-HE-Tag: 1621998266-755969 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: On Tue, 25 May 2021 20:36:18 -0400 Peter Xu wrote: > On Tue, May 25, 2021 at 05:15:58PM -0700, Andrew Morton wrote: > > This run afoul of Alistair's "mm: Device exclusive memory access", > > https://lkml.kernel.org/r/20210524132725.12697-8-apopple@nvidia.com > > > > `vma' is now undeclared. I think this? > > > > --- a/mm/memory.c~mm-userfaultfd-fix-uffd-wp-special-cases-for-fork-fix > > +++ a/mm/memory.c > > @@ -850,8 +850,8 @@ copy_nonpresent_pte(struct mm_struct *ds > > * exclusive entries currently only support private writable > > * (ie. COW) mappings. > > */ > > - VM_BUG_ON(!is_cow_mapping(vma->vm_flags)); > > - if (try_restore_exclusive_pte(src_mm, src_pte, vma, addr)) > > + VM_BUG_ON(!is_cow_mapping(dst_vma->vm_flags)); > > This one looks good, as both src_vma/dst_vma should have the same flags related > to is_cow. > > > + if (try_restore_exclusive_pte(src_mm, src_pte, dst_vma, addr)) > > Should this be s/dst_vma/src_vma/ perhaps? Alistairs please correct me > otherwise, as it tries to restore the pte for src mm not dst (the child). > > I haven't yet got time to look at the new series, planning to do it tomorrow > maybe.. but I see that it's already queued in -mm. Andrew, we do have chance > to go back if necessary, right? Sure. > I haven't looked at the rest, but I think try_restore_exclusive_pte() can at > least drop the *mm pointer as it's never used (even if we need, we've got > vma->vm_mm too).. OK, thanks. I just released a tree into linux-next (hopefully this blooper won't cause too much damage). Please send a suitable fixup.