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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 224E8C433FE for ; Wed, 30 Nov 2022 12:08:36 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232757AbiK3MIf (ORCPT ); Wed, 30 Nov 2022 07:08:35 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:56272 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231190AbiK3MId (ORCPT ); Wed, 30 Nov 2022 07:08:33 -0500 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 4E367659A for ; Wed, 30 Nov 2022 04:07:39 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1669810058; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=jnVdlteFV26Z76cEF4gxE55CdPW4P3QACX8nQF2ZXTo=; b=W/dSB4qs5hwMfYN4TjxxFnqFD4auu9K07/woj4RDIZunyWcd9qT2g9XoFZvOSjAqfTe4Ga sPDuA5GKhAnz1PJtE0E805fwucXHtgi6wF0TyYucotzcJnBT4lkI2YNflsI6f5EEvixFEq 5X6WL3hpHvkVlHRo2bXgnkAdSZ4Yo+A= Received: from mail-wm1-f69.google.com (mail-wm1-f69.google.com [209.85.128.69]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_128_GCM_SHA256) id us-mta-417-zZmfVxeUNNSJ56M3TzZaUw-1; Wed, 30 Nov 2022 07:07:37 -0500 X-MC-Unique: zZmfVxeUNNSJ56M3TzZaUw-1 Received: by mail-wm1-f69.google.com with SMTP id ay19-20020a05600c1e1300b003cf758f1617so905836wmb.5 for ; Wed, 30 Nov 2022 04:07:37 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to; bh=jnVdlteFV26Z76cEF4gxE55CdPW4P3QACX8nQF2ZXTo=; b=UzDkE45AX7sorf0DQUsi/t6YPsc79+ZoOuuB/+5RKD0tkO4CemHziDMU1P14yhuSvw MK/O7/76XBlRaQur9LlQFVIepBgUb+5FhLR3ZMAj5NmXRcREZ/1wdjXhi1LNn4v4dCf0 wC2iyvuRxKnU8Z89Ic4pNqpgUQ5Eh1cC52d3ql8SNLm1lU9EyX6BP3ZPbcUIEJt4y5Wx 4+GGdMp1rxxZ9SLzKZv6U4vvUc7hOztcMA3H8fSeCsA9CK7WcpcnpSjuNtLu5Sk9bFmk RQeHvW4bOclDoY7JvtxYHg+DQCLE7jUF50M0IV3OWNZjr1RssSaPRqKVoZPlN+s9l4I5 ltLQ== X-Gm-Message-State: ANoB5pkVa+tyV46yr/RCEXlLi51a/IeAMaYxCIZUIPrIoZP+ayQf8T/k v2O6kT6nxuZ8sYMN8C5Ufl3kwZ4GhN+QoWhtME36WlPcJkoxdjzWm/aTJGVtMc3b3o5fEzQiDAl a4QTidwvUIYTC6fj+ X-Received: by 2002:a05:600c:3c8e:b0:3d0:69f4:d3d0 with SMTP id bg14-20020a05600c3c8e00b003d069f4d3d0mr4598074wmb.93.1669810056113; Wed, 30 Nov 2022 04:07:36 -0800 (PST) X-Google-Smtp-Source: AA0mqf4PpVsPubG71ps8rgagttNzK50w8zECDxzJfF2enqQnAPQgsvcgKe3HBaErdsIeSxrgevrHjQ== X-Received: by 2002:a05:600c:3c8e:b0:3d0:69f4:d3d0 with SMTP id bg14-20020a05600c3c8e00b003d069f4d3d0mr4598054wmb.93.1669810055886; Wed, 30 Nov 2022 04:07:35 -0800 (PST) Received: from pc-4.home (2a01cb058918ce00dd1a5a4f9908f2d5.ipv6.abo.wanadoo.fr. [2a01:cb05:8918:ce00:dd1a:5a4f:9908:f2d5]) by smtp.gmail.com with ESMTPSA id j3-20020adfd203000000b002366c3eefccsm1368822wrh.109.2022.11.30.04.07.33 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 30 Nov 2022 04:07:35 -0800 (PST) Date: Wed, 30 Nov 2022 13:07:32 +0100 From: Guillaume Nault To: Benjamin Coddington Cc: Christoph Hellwig , netdev@vger.kernel.org, linux-kernel@vger.kernel.org, Philipp Reisner , Lars Ellenberg , Christoph =?iso-8859-1?Q?B=F6hmwalder?= , Jens Axboe , Josef Bacik , Keith Busch , Sagi Grimberg , Lee Duncan , Chris Leech , Mike Christie , "James E.J. Bottomley" , "Martin K. Petersen" , Valentina Manea , Shuah Khan , Greg Kroah-Hartman , David Howells , Marc Dionne , Steve French , Christine Caulfield , David Teigland , Mark Fasheh , Joel Becker , Joseph Qi , Eric Van Hensbergen , Latchesar Ionkov , Dominique Martinet , "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Ilya Dryomov , Xiubo Li , Trond Myklebust , Anna Schumaker , Chuck Lever , Jeff Layton , drbd-dev@lists.linbit.com, linux-block@vger.kernel.org, nbd@other.debian.org, linux-nvme@lists.infradead.org, open-iscsi@googlegroups.com, linux-scsi@vger.kernel.org, linux-usb@vger.kernel.org, linux-afs@lists.infradead.org, linux-cifs@vger.kernel.org, samba-technical@lists.samba.org, cluster-devel@redhat.com, ocfs2-devel@oss.oracle.com, v9fs-developer@lists.sourceforge.net, ceph-devel@vger.kernel.org, linux-nfs@vger.kernel.org Subject: Re: [PATCH v1 2/3] Treewide: Stop corrupting socket's task_frag Message-ID: <20221130120732.GB29316@pc-4.home> References: <20221129140242.GA15747@lst.de> <794DBAB0-EDAF-4DA2-A837-C1F99916BC8E@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <794DBAB0-EDAF-4DA2-A837-C1F99916BC8E@redhat.com> Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On Tue, Nov 29, 2022 at 11:47:47AM -0500, Benjamin Coddington wrote: > On 29 Nov 2022, at 9:02, Christoph Hellwig wrote: > > > Hmm. Having to set a flag to not accidentally corrupt per-task > > state seems a bit fragile. Wouldn't it make sense to find a way to opt > > into the feature only for sockets created from the syscall layer? > > It's totally fragile, and that's why it's currently broken in production. > The fragile ship sailed when networking decided to depend on users setting > the socket's GFP_ flags correctly to avoid corruption. > > Meantime, this problem needs fixing in a way that makes everyone happy. > This fix doesn't make it less fragile, but it may (hopefully) address the > previous criticisms enough that something gets done to fix it. Also, let's remember that while we're discussing how the kernel sould work in an ideal world, the reality is that production NFS systems crash randomly upon memory reclaim since commit a1231fda7e94 ("SUNRPC: Set memalloc_nofs_save() on all rpciod/xprtiod jobs"). Fixing that is just a matter of re-introducing GFP_NOFS on SUNRPC sockets (which has been proposed several times already). Then we'll have plenty of time to argue about how networking should use the per-task page_frag and how to remove GFP_NOFS in the long term.