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 DF0CFC32751 for ; Wed, 31 Jul 2019 23:01:01 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 9C46B206A2 for ; Wed, 31 Jul 2019 23:01:01 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=ziepe.ca header.i=@ziepe.ca header.b="ZqOvaIKn" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 9C46B206A2 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=ziepe.ca Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 397728E0003; Wed, 31 Jul 2019 19:01:01 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 34F168E0001; Wed, 31 Jul 2019 19:01:01 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 20D508E0003; Wed, 31 Jul 2019 19:01:01 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from mail-qk1-f200.google.com (mail-qk1-f200.google.com [209.85.222.200]) by kanga.kvack.org (Postfix) with ESMTP id 011CC8E0001 for ; Wed, 31 Jul 2019 19:01:01 -0400 (EDT) Received: by mail-qk1-f200.google.com with SMTP id k125so59323504qkc.12 for ; Wed, 31 Jul 2019 16:01:00 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:dkim-signature:date:from:to:cc:subject :message-id:references:mime-version:content-disposition:in-reply-to :user-agent; bh=his7K/u+JOrtxUOs2Ekh5bM+KWEwFmVBgmJqXbtUu9E=; b=ZpocwTtpN9LKeYY8C/L+0XRMp8QLV0N7EESF3tuvpkznpcKJ50JJXvIUANXofvmSwQ UCiWDFL3mQxwvcFLdDo1XYjaZMWwxy3ZIDYzNE1EuRlGA2vN1p3ML0EI25lI3Vlqohc9 wkza9BsDPJYHqzseVCAZiTwOSSqyeo3eA7t7fCPC6W2Lr7UmrrxdfLvR3j9+IdBwvRe3 JTUNpR0y//Px97CuWogEEIEn+udLazkgHwfEYrQEQt+gvb43+Dt/+tu+T4esYX3rbBAe JF5J0ngLJYiTKQfglA2AqaikAnKBA5yEJxukP28V/8kCSb5F9ELgVo4N6fG7CGqV+ZjY JSaA== X-Gm-Message-State: APjAAAWTrSTF6QdIuXuLOoPOUq9ntdvb3N3N1/EMLcOAD0OdIHlAoaFf c+P0bSFfq0zRwdZFEKWEansIZsKySXmDYcsyzxmCsTx6dCGiavZwL7Z9I7ifW3CYmad7HBMAuzt 2LK+qJCVY+EHrRHTW68dgBJCC5S1+Q9ZGNiN42zTlvOwZ9KggtyeqHy1qeNFkVXcM4Q== X-Received: by 2002:a37:9c81:: with SMTP id f123mr79935274qke.135.1564614060743; Wed, 31 Jul 2019 16:01:00 -0700 (PDT) X-Received: by 2002:a37:9c81:: with SMTP id f123mr79935202qke.135.1564614059808; Wed, 31 Jul 2019 16:00:59 -0700 (PDT) ARC-Seal: i=1; a=rsa-sha256; t=1564614059; cv=none; d=google.com; s=arc-20160816; b=OIuF9FXjpJXRuPbAupYuQqcd1I+VgDj2AUYse4Bo7w9m432Sl4g4NOkXCA2+HKACa/ cwdcISVmXmv79tRBogtpmT8LNtzvkLFdh90HcrC0SznCeEi+L4XY9WzGClp3l2fhJw3a WR5Mixu5KdOcWwdZwhtYrH1T9vrkTQFVqA7pP1vITuwnEVtNrfI9TN4yiHAFE9cAYKud L/vRH3IPF1A7yxOjcHLb7Tg+cDMMKYtacKKqFTcnvV9h96uTxmB/OJptP2cE7qP6+3ga iUi2Zi9Ga15nuQJBJ15zPb33F9rx2UIo/ePNy2VOyClSd8Pq9dfEjbIMsOk+j705S9Vf 0oCQ== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=user-agent:in-reply-to:content-disposition:mime-version:references :message-id:subject:cc:to:from:date:dkim-signature; bh=his7K/u+JOrtxUOs2Ekh5bM+KWEwFmVBgmJqXbtUu9E=; b=r+uJDqRxoxzmgJWKhQobAnpo3bK550n4sKybCnEDHaSik2C1tReEFQ40c9Zr/5o6Uh NbiNxElaZI/pjlldanaHxIPqdVJkiP1tj5lGiY2K1irDFBMOt3wgk3A+wFYeWJS4dEz4 YYwUn3LFHE4fI+f+95c/M6nO8bA4bcPS8CqR9y8zJwV06/jMuz1olSCzN+lYZHGuwf3C oKI/5ePjzH6jRmd4x4h63CxEonpxUhXVp3/AZTChCPD2fKeyY1pHo2WsqalVG69OG0cn fBjPmvJxyy+0GW+uw9ZXCcd5Ql7QNtGap4btZzDyYyNNHtWAIJcHiGJORWF8I/pYs+0M Fbdw== ARC-Authentication-Results: i=1; mx.google.com; dkim=pass header.i=@ziepe.ca header.s=google header.b=ZqOvaIKn; spf=pass (google.com: domain of jgg@ziepe.ca designates 209.85.220.65 as permitted sender) smtp.mailfrom=jgg@ziepe.ca Received: from mail-sor-f65.google.com (mail-sor-f65.google.com. [209.85.220.65]) by mx.google.com with SMTPS id y8sor91148335qtm.63.2019.07.31.16.00.59 for (Google Transport Security); Wed, 31 Jul 2019 16:00:59 -0700 (PDT) Received-SPF: pass (google.com: domain of jgg@ziepe.ca designates 209.85.220.65 as permitted sender) client-ip=209.85.220.65; Authentication-Results: mx.google.com; dkim=pass header.i=@ziepe.ca header.s=google header.b=ZqOvaIKn; spf=pass (google.com: domain of jgg@ziepe.ca designates 209.85.220.65 as permitted sender) smtp.mailfrom=jgg@ziepe.ca 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-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) 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 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