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=-2.4 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,USER_AGENT_SANE_1 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 59A5FC433FF for ; Wed, 31 Jul 2019 23:01:02 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 2ED8F208E4 for ; Wed, 31 Jul 2019 23:01:02 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=ziepe.ca header.i=@ziepe.ca header.b="ZqOvaIKn" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730544AbfGaXBA (ORCPT ); Wed, 31 Jul 2019 19:01:00 -0400 Received: from mail-qt1-f193.google.com ([209.85.160.193]:35899 "EHLO mail-qt1-f193.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727373AbfGaXBA (ORCPT ); Wed, 31 Jul 2019 19:01:00 -0400 Received: by mail-qt1-f193.google.com with SMTP id z4so68316319qtc.3 for ; Wed, 31 Jul 2019 16:00:59 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ziepe.ca; s=google; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to:user-agent; bh=his7K/u+JOrtxUOs2Ekh5bM+KWEwFmVBgmJqXbtUu9E=; b=ZqOvaIKn5gpXMKF0lFuPBJqJcfbMtb3MPGVVmN3aQsXXr9MSvDSwnBIoLdfs4Cduzu QRA8c1QAxNjNjf8z0l9WF9x2Kw8+F1laR/NQxc3pyjTGetdSmplJvdURFUqnq6fIi7Y5 JS4Uvm5qizwTDtKpRb8KoH2QzFqssZQiMkXG494iOUBy1xVC1xhi6b5WNlWd0gIvaub2 W1XaQLBaV1YKYGli71I0JUa9mD2l2THlCEAFuHc01L/n1KcqIaj1oCEo7xdECmJqx39w 8DGqiJA1GV5ZIbSfFrgl6Pwwxp6UZXG3UZ0N0Nuntbj6x+BE/tlQ9FyXqpoxRRJYgrFQ ADTw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to:user-agent; bh=his7K/u+JOrtxUOs2Ekh5bM+KWEwFmVBgmJqXbtUu9E=; b=NS4F1b04pvoOoyNn3xB9HIONrLxai055mrlZGNYBiFFcOrnprR7W8IQMLoB0G+pcu0 NqhrXTm2jLWMnYKQ0EyPS8s0fRQslBWwC+Cd6rMkNBZjlz6dVOjRJskF4psdNWXtoGgi HJ/hjGJJUBsSbeHOeZ935udPb/RRN1rgI0j98vVvMgRU2XMIIGc94a8GsAsr1hdmP/GT 0KmnDzszz1Mfo3GRwlY3tF93v2O4k6VWxchtSdAHLb/2sW8jaRElQJZQDExqj15+dVRs gYlqzgwxeHR+EijeJlB1Frf9EXKnSmde7l80AZKc69YoqXwcFGTtehnyB2p7nRp9xM5A X9/Q== X-Gm-Message-State: APjAAAXSCErzRtcxHS8ggEbaod9fo8iyA8iQ+ACJPbgiBMYP80ms81i6 WjX4C2ZEbV2215gpgH4FOlvX3A== X-Google-Smtp-Source: APXvYqwJPf0PqUhqgGpVR2IzxGvlfGykM1M7nRsba5YS0Ne3y5wjASuoEvOh6D7uIAmXvcUuYYR1nQ== X-Received: by 2002:ac8:688:: with SMTP id f8mr11797584qth.130.1564614059446; Wed, 31 Jul 2019 16:00:59 -0700 (PDT) Received: from ziepe.ca (hlfxns017vw-156-34-55-100.dhcp-dynamic.fibreop.ns.bellaliant.net. [156.34.55.100]) by smtp.gmail.com with ESMTPSA id n18sm29218512qtr.28.2019.07.31.16.00.57 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Wed, 31 Jul 2019 16:00:58 -0700 (PDT) Received: from jgg by mlx.ziepe.ca with local (Exim 4.90_1) (envelope-from ) id 1hsxab-00009Y-B9; Wed, 31 Jul 2019 20:00:57 -0300 Date: Wed, 31 Jul 2019 20:00:57 -0300 From: Jason Gunthorpe To: Jason Wang Cc: "Michael S. Tsirkin" , syzbot , aarcange@redhat.com, akpm@linux-foundation.org, christian@brauner.io, davem@davemloft.net, ebiederm@xmission.com, elena.reshetova@intel.com, guro@fb.com, hch@infradead.org, james.bottomley@hansenpartnership.com, jglisse@redhat.com, keescook@chromium.org, ldv@altlinux.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-parisc@vger.kernel.org, luto@amacapital.net, mhocko@suse.com, mingo@kernel.org, namit@vmware.com, peterz@infradead.org, syzkaller-bugs@googlegroups.com, viro@zeniv.linux.org.uk, wad@chromium.org Subject: Re: WARNING in __mmdrop Message-ID: <20190731230057.GA32346@ziepe.ca> References: <20190726094756-mutt-send-email-mst@kernel.org> <0792ee09-b4b7-673c-2251-e5e0ce0fbe32@redhat.com> <20190729045127-mutt-send-email-mst@kernel.org> <4d43c094-44ed-dbac-b863-48fc3d754378@redhat.com> <20190729104028-mutt-send-email-mst@kernel.org> <96b1d67c-3a8d-1224-e9f0-5f7725a3dc10@redhat.com> <20190730110633-mutt-send-email-mst@kernel.org> <421a1af6-df06-e4a6-b34f-526ac123bc4a@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <421a1af6-df06-e4a6-b34f-526ac123bc4a@redhat.com> User-Agent: Mutt/1.9.4 (2018-02-28) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Jul 31, 2019 at 04:49:32PM +0800, Jason Wang wrote: > Yes, looking at the synchronization implemented by other MMU notifiers. > Vhost is even the simplest. I think that is only because it calls gup under a spinlock, which is, IMHO, not great. Jason