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=-7.3 required=3.0 tests=BAYES_00,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 97766C04FF3 for ; Mon, 24 May 2021 08:39:25 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 72183611AC for ; Mon, 24 May 2021 08:39:25 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232427AbhEXIkw (ORCPT ); Mon, 24 May 2021 04:40:52 -0400 Received: from mx2.suse.de ([195.135.220.15]:52538 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232415AbhEXIks (ORCPT ); Mon, 24 May 2021 04:40:48 -0400 X-Virus-Scanned: by amavisd-new at test-mx.suse.de DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.cz; s=susede2_rsa; t=1621845559; h=from:from:reply-to: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=mjxvWAvOCJRMEsP/LeDM6TS4/Fq6dQC1dCNTIlx2sgc=; b=WmCYjj0zXXpbdQSFXXM2fC8bPnZhxUcQOxQ10YDIyRgnnChp8HU714tRRlWxYaAaIIyul5 VpR5zFWOFkpRXzJr+lAF1MbHrQQU5qMLAUS/85fkSvqlZOv9Q2FnHEvUJPNBPn4+bo1Apw 0OfWqG5mmVxRCl562CEHfaD52h07AKM= DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=suse.cz; s=susede2_ed25519; t=1621845559; h=from:from:reply-to: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=mjxvWAvOCJRMEsP/LeDM6TS4/Fq6dQC1dCNTIlx2sgc=; b=l50JzRBtn8w7158ZD3kE3ZFSfqo873ry/nCxpkwHMV4uA2Z/Fv3nDNAT4Z1RehOWNopnkt xW52JOBaZV+J1VCA== Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id 8720BABB1; Mon, 24 May 2021 08:39:19 +0000 (UTC) Received: by quack2.suse.cz (Postfix, from userid 1000) id 1DDAD1F2CA2; Mon, 24 May 2021 10:39:19 +0200 (CEST) Date: Mon, 24 May 2021 10:39:19 +0200 From: Jan Kara To: Andreas Gruenbacher Cc: Jan Kara , Andy Lutomirski , Alexander Viro , cluster-devel , linux-fsdevel , Linux-MM Subject: Re: [PATCH 6/6] gfs2: Fix mmap + page fault deadlocks (part 2) Message-ID: <20210524083919.GA32705@quack2.suse.cz> References: <20210520122536.1596602-1-agruenba@redhat.com> <20210520122536.1596602-7-agruenba@redhat.com> <20210520133015.GC18952@quack2.suse.cz> <20210521152352.GQ18952@quack2.suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.10.1 (2018-07-13) Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org On Fri 21-05-21 17:46:04, Andreas Gruenbacher wrote: > On Fri, May 21, 2021 at 5:23 PM Jan Kara wrote: > > On Thu 20-05-21 16:07:56, Andreas Gruenbacher wrote: > > > > So you probably need to add a new VM_FAULT_ > > > > return code that will behave like VM_FAULT_SIGBUS except it will not raise > > > > the signal. > > > > > > A new VM_FAULT_* flag might make the code easier to read, but I don't > > > know if we can have one. > > > > Well, this is kernel-internal API and there's still plenty of space in > > vm_fault_reason. > > That's in the context of the page fault. The other issue is how to > propagate that out through iov_iter_fault_in_readable -> > fault_in_pages_readable -> __get_user, for example. I don't think > there's much of a chance to get an additional error code out of > __get_user and __put_user. Yes, at that level we'd get EFAULT as in any other case. Really the only difference of the new VM_FAULT_ error code from a case of "standard" error and VM_FAULT_SIGBUS would be not raising the signal. Honza -- Jan Kara SUSE Labs, CR From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jan Kara Date: Mon, 24 May 2021 10:39:19 +0200 Subject: [Cluster-devel] [PATCH 6/6] gfs2: Fix mmap + page fault deadlocks (part 2) In-Reply-To: References: <20210520122536.1596602-1-agruenba@redhat.com> <20210520122536.1596602-7-agruenba@redhat.com> <20210520133015.GC18952@quack2.suse.cz> <20210521152352.GQ18952@quack2.suse.cz> Message-ID: <20210524083919.GA32705@quack2.suse.cz> List-Id: To: cluster-devel.redhat.com MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit On Fri 21-05-21 17:46:04, Andreas Gruenbacher wrote: > On Fri, May 21, 2021 at 5:23 PM Jan Kara wrote: > > On Thu 20-05-21 16:07:56, Andreas Gruenbacher wrote: > > > > So you probably need to add a new VM_FAULT_ > > > > return code that will behave like VM_FAULT_SIGBUS except it will not raise > > > > the signal. > > > > > > A new VM_FAULT_* flag might make the code easier to read, but I don't > > > know if we can have one. > > > > Well, this is kernel-internal API and there's still plenty of space in > > vm_fault_reason. > > That's in the context of the page fault. The other issue is how to > propagate that out through iov_iter_fault_in_readable -> > fault_in_pages_readable -> __get_user, for example. I don't think > there's much of a chance to get an additional error code out of > __get_user and __put_user. Yes, at that level we'd get EFAULT as in any other case. Really the only difference of the new VM_FAULT_ error code from a case of "standard" error and VM_FAULT_SIGBUS would be not raising the signal. Honza -- Jan Kara SUSE Labs, CR