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=-8.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS,URIBL_BLOCKED, USER_AGENT_GIT 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 AD922C32789 for ; Fri, 2 Nov 2018 17:17:05 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 8101F2082E for ; Fri, 2 Nov 2018 17:17:05 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 8101F2082E Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=arm.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728132AbeKCCYz (ORCPT ); Fri, 2 Nov 2018 22:24:55 -0400 Received: from foss.arm.com ([217.140.101.70]:44238 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726085AbeKCCYy (ORCPT ); Fri, 2 Nov 2018 22:24:54 -0400 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.72.51.249]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 4C9EDA78; Fri, 2 Nov 2018 10:17:03 -0700 (PDT) Received: from filthy-habits.cambridge.arm.com (filthy-habits.cambridge.arm.com [10.1.196.62]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 572D23F71E; Fri, 2 Nov 2018 10:17:02 -0700 (PDT) From: Marc Zyngier To: David Howells , Al Viro Cc: linux-kernel@vger.kernel.org, Will Deacon Subject: [PATCH] iov_iter: Fix 9p virtio breakage Date: Fri, 2 Nov 2018 17:16:51 +0000 Message-Id: <20181102171651.97671-1-marc.zyngier@arm.com> X-Mailer: git-send-email 2.19.1 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org When switching to the new iovec accessors, a negation got subtly dropped, leading to 9p being remarkably broken (here with kvmtool): [ 7.430941] VFS: Mounted root (9p filesystem) on device 0:15. [ 7.432080] devtmpfs: mounted [ 7.432717] Freeing unused kernel memory: 1344K [ 7.433658] Run /virt/init as init process Warning: unable to translate guest address 0x7e00902ff000 to host Warning: unable to translate guest address 0x7e00902fefc0 to host Warning: unable to translate guest address 0x7e00902ff000 to host Warning: unable to translate guest address 0x7e008febef80 to host Warning: unable to translate guest address 0x7e008febf000 to host Warning: unable to translate guest address 0x7e008febef00 to host Warning: unable to translate guest address 0x7e008febf000 to host [ 7.436376] Kernel panic - not syncing: Requested init /virt/init failed (error -8). [ 7.437554] CPU: 29 PID: 1 Comm: swapper/0 Not tainted 4.19.0-rc8-02267-g00e23707442a #291 [ 7.439006] Hardware name: linux,dummy-virt (DT) [ 7.439902] Call trace: [ 7.440387] dump_backtrace+0x0/0x148 [ 7.441104] show_stack+0x14/0x20 [ 7.441768] dump_stack+0x90/0xb4 [ 7.442425] panic+0x120/0x27c [ 7.443036] kernel_init+0xa4/0x100 [ 7.443725] ret_from_fork+0x10/0x18 [ 7.444444] SMP: stopping secondary CPUs [ 7.445391] Kernel Offset: disabled [ 7.446169] CPU features: 0x0,23000438 [ 7.446974] Memory Limit: none [ 7.447645] ---[ end Kernel panic - not syncing: Requested init /virt/init failed (error -8). ]--- Restoring the missing "!" brings the guest back to life. Fixes: 00e23707442a ("iov_iter: Use accessor function") Reported-by: Will Deacon Signed-off-by: Marc Zyngier --- net/9p/trans_virtio.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/net/9p/trans_virtio.c b/net/9p/trans_virtio.c index 91981970f542..b1d39cabf125 100644 --- a/net/9p/trans_virtio.c +++ b/net/9p/trans_virtio.c @@ -329,7 +329,7 @@ static int p9_get_mapped_pages(struct virtio_chan *chan, if (!iov_iter_count(data)) return 0; - if (iov_iter_is_kvec(data)) { + if (!iov_iter_is_kvec(data)) { int n; /* * We allow only p9_max_pages pinned. We wait for the -- 2.19.1