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=-8.5 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS,USER_AGENT_MUTT 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 0C902C43387 for ; Wed, 9 Jan 2019 05:05:14 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id CB769206BA for ; Wed, 9 Jan 2019 05:05:13 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729172AbfAIFFM (ORCPT ); Wed, 9 Jan 2019 00:05:12 -0500 Received: from mx1.redhat.com ([209.132.183.28]:50592 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725440AbfAIFFM (ORCPT ); Wed, 9 Jan 2019 00:05:12 -0500 Received: from smtp.corp.redhat.com (int-mx07.intmail.prod.int.phx2.redhat.com [10.5.11.22]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id BE1DEC068BD3; Wed, 9 Jan 2019 05:05:11 +0000 (UTC) Received: from xz-x1 (dhcp-14-128.nay.redhat.com [10.66.14.128]) by smtp.corp.redhat.com (Postfix) with ESMTPS id DB428105705F; Wed, 9 Jan 2019 05:05:08 +0000 (UTC) Date: Wed, 9 Jan 2019 13:05:05 +0800 From: Peter Xu To: Andrea Arcangeli Cc: Andrew Morton , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Mike Rapoport , Mike Kravetz , "Dr. David Alan Gilbert" Subject: Re: [PATCH 1/1] mm/hugetlb.c: teach follow_hugetlb_page() to handle FOLL_NOWAIT Message-ID: <20190109050505.GC12837@xz-x1> References: <20190109020203.26669-1-aarcange@redhat.com> <20190109020203.26669-2-aarcange@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20190109020203.26669-2-aarcange@redhat.com> User-Agent: Mutt/1.10.1 (2018-07-13) X-Scanned-By: MIMEDefang 2.84 on 10.5.11.22 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.32]); Wed, 09 Jan 2019 05:05:12 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Jan 08, 2019 at 09:02:03PM -0500, Andrea Arcangeli wrote: > hugetlb needs the same fix as faultin_nopage (which was applied in > 96312e61282ae3f6537a562625706498cbc75594) or KVM hangs because it > thinks the mmap_sem was already released by hugetlb_fault() if it > returned VM_FAULT_RETRY, but it wasn't in the FOLL_NOWAIT case. > > Fixes: ce53053ce378 ("kvm: switch get_user_page_nowait() to get_user_pages_unlocked()") > Signed-off-by: Andrea Arcangeli > Tested-by: "Dr. David Alan Gilbert" > Reported-by: "Dr. David Alan Gilbert" FWIW: Reviewed-by: Peter Xu > --- > mm/hugetlb.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > diff --git a/mm/hugetlb.c b/mm/hugetlb.c > index e37efd5d8318..b3622d7888c8 100644 > --- a/mm/hugetlb.c > +++ b/mm/hugetlb.c > @@ -4301,7 +4301,8 @@ long follow_hugetlb_page(struct mm_struct *mm, struct vm_area_struct *vma, > break; > } > if (ret & VM_FAULT_RETRY) { > - if (nonblocking) > + if (nonblocking && > + !(fault_flags & FAULT_FLAG_RETRY_NOWAIT)) > *nonblocking = 0; > *nr_pages = 0; > /* Regards, -- Peter Xu