| lists.openwall.net | lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC | |
|
Open Source and information security mailing list archives
| ||
|
Message-ID: <20131123225358.GB5402@kroah.com>
Date: Sat, 23 Nov 2013 14:53:58 -0800
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: "Rafael J. Wysocki" <rjw@...ysocki.net>
Cc: Bjorn Helgaas <bhelgaas@...gle.com>, Tejun Heo <tj@...nel.org>,
Mika Westerberg <mika.westerberg@...ux.intel.com>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
"James E.J. Bottomley" <JBottomley@...allels.com>
Subject: Re: [PATCH] sysfs: handle duplicate removal attempts in
sysfs_remove_group()
On Sat, Nov 23, 2013 at 11:56:48PM +0100, Rafael J. Wysocki wrote:
> On Friday, November 22, 2013 08:43:55 AM Bjorn Helgaas wrote:
> > [+cc Rafael, James]
> >
> > On Tue, Nov 19, 2013 at 11:18 PM, Tejun Heo <tj@...nel.org> wrote:
> > > (cc'ing Bjorn)
> > >
> > > Hello,
> > >
> > > On Tue, Nov 19, 2013 at 03:09:58PM +0200, Mika Westerberg wrote:
> > >> Commit bcdde7e221a8 (sysfs: make __sysfs_remove_dir() recursive) changed
> > >> the behavior so that directory removals will be done recursively. This
> > >> means that the sysfs group might already be removed if its parent directory
> > >> has been removed.
> > >>
> > >> The current code outputs warnings similar to following log snippet when it
> > >> detects that there is no group for the given kobject:
> > >>
> > >> WARNING: CPU: 0 PID: 4 at fs/sysfs/group.c:214 sysfs_remove_group+0xc6/0xd0()
> > >> sysfs group ffffffff81c6f1e0 not found for kobject 'host7'
> > >> Modules linked in:
> > >> CPU: 0 PID: 4 Comm: kworker/0:0 Not tainted 3.12.0+ #13
> > >> Hardware name: /D33217CK, BIOS GKPPT10H.86A.0042.2013.0422.1439 04/22/2013
> > >> Workqueue: kacpi_hotplug acpi_hotplug_work_fn
> > >> 0000000000000009 ffff8801002459b0 ffffffff817daab1 ffff8801002459f8
> > >> ffff8801002459e8 ffffffff810436b8 0000000000000000 ffffffff81c6f1e0
> > >> ffff88006d440358 ffff88006d440188 ffff88006e8b4c28 ffff880100245a48
> > >> Call Trace:
> > >> [<ffffffff817daab1>] dump_stack+0x45/0x56
> > >> [<ffffffff810436b8>] warn_slowpath_common+0x78/0xa0
> > >> [<ffffffff81043727>] warn_slowpath_fmt+0x47/0x50
> > >> [<ffffffff811ae526>] sysfs_remove_group+0xc6/0xd0
> > >> [<ffffffff81432f7e>] dpm_sysfs_remove+0x3e/0x50
> > >> [<ffffffff8142a0d0>] device_del+0x40/0x1b0
> > >> [<ffffffff8142a24d>] device_unregister+0xd/0x20
> > >> [<ffffffff8144131a>] scsi_remove_host+0xba/0x110
> > >> [<ffffffff8145f526>] ata_host_detach+0xc6/0x100
> > >> [<ffffffff8145f578>] ata_pci_remove_one+0x18/0x20
> > >> [<ffffffff812e8f48>] pci_device_remove+0x28/0x60
> > >> [<ffffffff8142d854>] __device_release_driver+0x64/0xd0
> > >> [<ffffffff8142d8de>] device_release_driver+0x1e/0x30
> > >> [<ffffffff8142d257>] bus_remove_device+0xf7/0x140
> > >> [<ffffffff8142a1b1>] device_del+0x121/0x1b0
> > >> [<ffffffff812e43d4>] pci_stop_bus_device+0x94/0xa0
> > >> [<ffffffff812e437b>] pci_stop_bus_device+0x3b/0xa0
> > >> [<ffffffff812e437b>] pci_stop_bus_device+0x3b/0xa0
> > >> [<ffffffff812e44dd>] pci_stop_and_remove_bus_device+0xd/0x20
> > >> [<ffffffff812fc743>] trim_stale_devices+0x73/0xe0
> > >> [<ffffffff812fc78b>] trim_stale_devices+0xbb/0xe0
> > >> [<ffffffff812fc78b>] trim_stale_devices+0xbb/0xe0
> > >> [<ffffffff812fcb6e>] acpiphp_check_bridge+0x7e/0xd0
> > >> [<ffffffff812fd90d>] hotplug_event+0xcd/0x160
> > >> [<ffffffff812fd9c5>] hotplug_event_work+0x25/0x60
> > >> [<ffffffff81316749>] acpi_hotplug_work_fn+0x17/0x22
> > >> [<ffffffff8105cf3a>] process_one_work+0x17a/0x430
> > >> [<ffffffff8105db29>] worker_thread+0x119/0x390
> > >> [<ffffffff81063a5d>] kthread+0xcd/0xf0
> > >> [<ffffffff817eb33c>] ret_from_fork+0x7c/0xb0
> > >
> > > So, we do have cases where the parent is removed before the child. I
> > > suppose the parent pci bridge is removed already? AFAICS this
> > > shouldn't break anything but people did seem to expect the removals to
> > > be ordered from child to parent. Bjorn, is this something you expect
> > > to happened?
> >
> > I do not expect a PCI bridge to be removed before the devices below
> > it. We should be removing all the children before removing the parent
> > bridge.
> >
> > But is this related to PCI? I don't see the connection yet. I tried
> > to look into this a bit (my notes are at
> > https://bugzilla.kernel.org/show_bug.cgi?id=65281), but I haven't
> > figured out the big-picture problem yet.
>
> OK, so I think I've figured this out.
>
> As I wrote in the above BZ entry, after the Tejun's patch the
> device_del() in pci_stop_dev() removes the subordinate bus object's
> "power" directory among other things and because of that the warning
> triggers when we do the pci_remove_bus() in pci_remove_bus_device()
> for the same device.
>
> The appended patch fixes it for me, but Greg has already taken the
> Mika's one, so this one isn't really necessary. In case you think it
> would be useful to apply it anyway, please let me know and I submit it
> properly with a changelog etc.
I can revert Mika's patch, as it would be good to catch these kinds of
errors.
> ---
> drivers/pci/remove.c | 4 +++-
> 1 file changed, 3 insertions(+), 1 deletion(-)
>
> Index: linux-pm/drivers/pci/remove.c
> ===================================================================
> --- linux-pm.orig/drivers/pci/remove.c
> +++ linux-pm/drivers/pci/remove.c
> @@ -24,7 +24,7 @@ static void pci_stop_dev(struct pci_dev
> if (dev->is_added) {
> pci_proc_detach_device(dev);
> pci_remove_sysfs_dev_files(dev);
> - device_del(&dev->dev);
> + device_release_driver(&dev->dev);
> dev->is_added = 0;
> }
>
> @@ -34,6 +34,8 @@ static void pci_stop_dev(struct pci_dev
>
> static void pci_destroy_dev(struct pci_dev *dev)
> {
> + device_del(&dev->dev);
> +
> down_write(&pci_bus_sem);
> list_del(&dev->bus_list);
> up_write(&pci_bus_sem);
This looks good, thanks for finding this. I suggest resending it with a
changelog so that Bjorn can get it into 3.13.
thanks,
greg k-h
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
Powered by blists - more mailing lists