Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752596AbdLLRCh (ORCPT ); Tue, 12 Dec 2017 12:02:37 -0500 Received: from mx1.redhat.com ([209.132.183.28]:53018 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752077AbdLLRCb (ORCPT ); Tue, 12 Dec 2017 12:02:31 -0500 Date: Tue, 12 Dec 2017 18:02:23 +0100 From: Cornelia Huck To: Mark Rutland Cc: linux-kernel@vger.kernel.org, "Michael S . Tsirkin" , weiping zhang , virtualization@lists.linux-foundation.org Subject: Re: [PATCHv2] virtio_mmio: fix devm cleanup Message-ID: <20171212180223.2dfb3b40.cohuck@redhat.com> In-Reply-To: <20171212134550.18378-1-mark.rutland@arm.com> References: <20171212134550.18378-1-mark.rutland@arm.com> Organization: Red Hat GmbH MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.27]); Tue, 12 Dec 2017 17:02:30 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2999 Lines: 67 On Tue, 12 Dec 2017 13:45:50 +0000 Mark Rutland wrote: > Recent rework of the virtio_mmio probe/remove paths balanced a > devm_ioremap() with an iounmap() rather than its devm variant. This ends > up corrupting the devm datastructures, and results in the following > boot-time splat on arm64 under QEMU 2.9.0: > > [ 3.450397] ------------[ cut here ]------------ > [ 3.453822] Trying to vfree() nonexistent vm area (00000000c05b4844) > [ 3.460534] WARNING: CPU: 1 PID: 1 at mm/vmalloc.c:1525 __vunmap+0x1b8/0x220 > [ 3.475898] Kernel panic - not syncing: panic_on_warn set ... > [ 3.475898] > [ 3.493933] CPU: 1 PID: 1 Comm: swapper/0 Not tainted 4.15.0-rc3 #1 > [ 3.513109] Hardware name: linux,dummy-virt (DT) > [ 3.525382] Call trace: > [ 3.531683] dump_backtrace+0x0/0x368 > [ 3.543921] show_stack+0x20/0x30 > [ 3.547767] dump_stack+0x108/0x164 > [ 3.559584] panic+0x25c/0x51c > [ 3.569184] __warn+0x29c/0x31c > [ 3.576023] report_bug+0x1d4/0x290 > [ 3.586069] bug_handler.part.2+0x40/0x100 > [ 3.597820] bug_handler+0x4c/0x88 > [ 3.608400] brk_handler+0x11c/0x218 > [ 3.613430] do_debug_exception+0xe8/0x318 > [ 3.627370] el1_dbg+0x18/0x78 > [ 3.634037] __vunmap+0x1b8/0x220 > [ 3.648747] vunmap+0x6c/0xc0 > [ 3.653864] __iounmap+0x44/0x58 > [ 3.659771] devm_ioremap_release+0x34/0x68 > [ 3.672983] release_nodes+0x404/0x880 > [ 3.683543] devres_release_all+0x6c/0xe8 > [ 3.695692] driver_probe_device+0x250/0x828 > [ 3.706187] __driver_attach+0x190/0x210 > [ 3.717645] bus_for_each_dev+0x14c/0x1f0 > [ 3.728633] driver_attach+0x48/0x78 > [ 3.740249] bus_add_driver+0x26c/0x5b8 > [ 3.752248] driver_register+0x16c/0x398 > [ 3.757211] __platform_driver_register+0xd8/0x128 > [ 3.770860] virtio_mmio_init+0x1c/0x24 > [ 3.782671] do_one_initcall+0xe0/0x398 > [ 3.791890] kernel_init_freeable+0x594/0x660 > [ 3.798514] kernel_init+0x18/0x190 > [ 3.810220] ret_from_fork+0x10/0x18 > > To fix this, we can simply rip out the explicit cleanup that the devm > infrastructure will do for us when our probe function returns an error > code, or when our remove function returns. > > We only need to ensure that we call put_device() if a call to > register_virtio_device() fails in the probe path. > > Signed-off-by: Mark Rutland > Fixes: 7eb781b1bbb7136f ("virtio_mmio: add cleanup for virtio_mmio_probe") > Fixes: 25f32223bce5c580 ("virtio_mmio: add cleanup for virtio_mmio_remove") > Cc: Cornelia Huck > Cc: Michael S. Tsirkin > Cc: weiping zhang > Cc: virtualization@lists.linux-foundation.org > --- > drivers/virtio/virtio_mmio.c | 43 +++++++++---------------------------------- > 1 file changed, 9 insertions(+), 34 deletions(-) In the hope that I have grokked the devm_* interface by now, Reviewed-by: Cornelia Huck