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=-0.8 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS autolearn=no 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 1764BC28CBC for ; Thu, 7 May 2020 01:35:25 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id C102A20736 for ; Thu, 7 May 2020 01:35:24 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=joelfernandes.org header.i=@joelfernandes.org header.b="usOpsGc2" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org C102A20736 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=joelfernandes.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 2264E900007; Wed, 6 May 2020 21:35:24 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 1D786900004; Wed, 6 May 2020 21:35:24 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 0C5D5900007; Wed, 6 May 2020 21:35:24 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0217.hostedemail.com [216.40.44.217]) by kanga.kvack.org (Postfix) with ESMTP id E4A0D900004 for ; Wed, 6 May 2020 21:35:23 -0400 (EDT) Received: from smtpin17.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay02.hostedemail.com (Postfix) with ESMTP id 94F43EFE8 for ; Thu, 7 May 2020 01:35:23 +0000 (UTC) X-FDA: 76788205326.17.crib18_2f0db089b694f X-HE-Tag: crib18_2f0db089b694f X-Filterd-Recvd-Size: 3628 Received: from mail-io1-f65.google.com (mail-io1-f65.google.com [209.85.166.65]) by imf07.hostedemail.com (Postfix) with ESMTP for ; Thu, 7 May 2020 01:35:23 +0000 (UTC) Received: by mail-io1-f65.google.com with SMTP id w11so4383324iov.8 for ; Wed, 06 May 2020 18:35:23 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=joelfernandes.org; s=google; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=sSQgeUzDc0Ws4bUG9eu4KJ9IiMZF0azB+bvY4wjW68Q=; b=usOpsGc2ooVJ9JUs6gxetJRbdtbLNuADqFfE5M9fvDF6oIA0h5x3iVA+4ngzBW9V6v nlIelZ/Mblmt+6SpqJ0cIZR8SJ/fwPVdI1BWynIATxF++YRYsTrPklVXrH7PyRGCRh+i SaDBiHImXZq0HpP+gMdsjxqmfkGP1sscwuedM= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=sSQgeUzDc0Ws4bUG9eu4KJ9IiMZF0azB+bvY4wjW68Q=; b=nOzYoY9zKVujGRpxE0MjCbn7oMRRN8tYNIbqlS6CGbY+zZ0EozCaYjC3Kfh3Og1tMp XgK4louR2yQgLm043bxRwtNkt5uDTsUdhzAdxY4gqrEYcsr6MvjX4QzfvzSR/oLpImPz YaOkWIUOZp4zxacjTY/+RLtPAoUXyhcJzW3gHZkms03MVNrLFvoUJAYNUoav3Q/qrVTk HFMgkoDYUsfcxkFhUJ6iDHMr+dQnX6rOynfmzYBTl8uAYlaRnJWH7IsCfb96oZiRu8ZF 4YLDD2q+4uM4OIhlHWVxAKh49vXIAEIE4nMYyaJe59aqBMr0g8AVCQP+ppizRnnFru1h 94vA== X-Gm-Message-State: AGi0Pub6FDA6X1d7gEubxnWXJx7YmN09yA0XvyF93polyFi4k/78n+5Y hKbIkt/z85Snm6i6IPBM285DLFiKXARZSKPffDzCBdLM X-Google-Smtp-Source: APiQypJm6BQfKoiRqEjddc6PWtsPlFYtuVAqgoS8S0MrVf7FZnlKR4QKeTS+VWu2+k315cqqwmUA1wA4/G2Z1Pv1oeQ= X-Received: by 2002:a6b:bc85:: with SMTP id m127mr11138943iof.89.1588815322685; Wed, 06 May 2020 18:35:22 -0700 (PDT) MIME-Version: 1.0 References: <20200506172158.218366-1-bgeffon@google.com> In-Reply-To: From: Joel Fernandes Date: Wed, 6 May 2020 21:35:10 -0400 Message-ID: Subject: Re: [PATCH] userfaultfd: fix remap event with MREMAP_DONTUNMAP. To: Brian Geffon Cc: Andrew Morton , "Michael S . Tsirkin" , LKML , linux-mm , Andrea Arcangeli , Sonny Rao , Minchan Kim , "Kirill A . Shutemov" Content-Type: text/plain; charset="UTF-8" X-Bogosity: Ham, tests=bogofilter, spamicity=0.000002, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Wed, May 6, 2020 at 9:11 PM Brian Geffon wrote: > > > > - mremap_userfaultfd_complete(&uf, addr, new_addr, old_len); > > > + mremap_userfaultfd_complete(&uf, addr, ret, old_len); > > > > Not super familiar with this code, but thought I'd ask, does ret > > to be checked for -ENOMEM before calling mremap_userfaultfd_complete? > > Sorry if I missed something. > > No, mremap_userfaultfd_complete will do a check similar to > offset_in_page() by checking the page mask. > It does (to & ~PAGE_MASK) to check for a non-aligned "to" value, so we're good. > > Additionally, earlier in the process then ctx will be null because we > will have never called mremap_userfaultfd_prep, > and mremap_userfaultfd_complete will check if there is a context > before proceeding. Makes sense. thanks, - Joel