Date:   Thu, 23 Aug 2018 17:41:55 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     Sergei Shtylyov <sergei.shtylyov@...entembedded.com>
Cc:     linux-kernel@...r.kernel.org, stable@...r.kernel.org,
        Lorenzo Pieralisi <lorenzo.pieralisi@....com>,
        Bjorn Helgaas <bhelgaas@...gle.com>,
        Linus Walleij <linus.walleij@...aro.org>
Subject: Re: [PATCH 4.14 210/217] PCI: OF: Fix I/O space page leak

On Thu, Aug 23, 2018 at 06:33:47PM +0300, Sergei Shtylyov wrote:
> On 08/23/2018 06:27 PM, Greg Kroah-Hartman wrote:
> > On Thu, Aug 23, 2018 at 06:20:31PM +0300, Sergei Shtylyov wrote:
> >> On 08/23/2018 02:56 PM, Greg Kroah-Hartman wrote:
> >>> On Thu, Aug 23, 2018 at 01:17:28PM +0200, Greg Kroah-Hartman wrote:
> >>>> On Thu, Aug 23, 2018 at 01:57:35PM +0300, Sergei Shtylyov wrote:
> >>>>> On 08/23/2018 10:55 AM, Greg Kroah-Hartman wrote:
> >>>>>
> >>>>>> 4.14-stable review patch.  If anyone has any objections, please let me know.
> >>>>>>
> >>>>>> ------------------
> >>>>>>
> >>>>>> From: Sergei Shtylyov <sergei.shtylyov@...entembedded.com>
> >>>>>>
> >>>>>> commit a5fb9fb023a1435f2b42bccd7f547560f3a21dc3 upstream.
> >>>>>>
> >>>>>> When testing the R-Car PCIe driver on the Condor board, if the PCIe PHY
> >>>>>> driver was left disabled, the kernel crashed with this BUG:
> >>>>>>
> >>>>>>   kernel BUG at lib/ioremap.c:72!
> >>>>>>   Internal error: Oops - BUG: 0 [#1] PREEMPT SMP
> >>>>>>   Modules linked in:
> >>>>>>   CPU: 0 PID: 39 Comm: kworker/0:1 Not tainted 4.17.0-dirty #1092
> >>>>>>   Hardware name: Renesas Condor board based on r8a77980 (DT)
> >>>>>>   Workqueue: events deferred_probe_work_func
> >>>>>>   pstate: 80000005 (Nzcv daif -PAN -UAO)
> >>>>>>   pc : ioremap_page_range+0x370/0x3c8
> >>>>>>   lr : ioremap_page_range+0x40/0x3c8
> >>>>>>   sp : ffff000008da39e0
> >>>>>>   x29: ffff000008da39e0 x28: 00e8000000000f07
> >>>>>>   x27: ffff7dfffee00000 x26: 0140000000000000
> >>>>>>   x25: ffff7dfffef00000 x24: 00000000000fe100
> >>>>>>   x23: ffff80007b906000 x22: ffff000008ab8000
> >>>>>>   x21: ffff000008bb1d58 x20: ffff7dfffef00000
> >>>>>>   x19: ffff800009c30fb8 x18: 0000000000000001
> >>>>>>   x17: 00000000000152d0 x16: 00000000014012d0
> >>>>>>   x15: 0000000000000000 x14: 0720072007200720
> >>>>>>   x13: 0720072007200720 x12: 0720072007200720
> >>>>>>   x11: 0720072007300730 x10: 00000000000000ae
> >>>>>>   x9 : 0000000000000000 x8 : ffff7dffff000000
> >>>>>>   x7 : 0000000000000000 x6 : 0000000000000100
> >>>>>>   x5 : 0000000000000000 x4 : 000000007b906000
> >>>>>>   x3 : ffff80007c61a880 x2 : ffff7dfffeefffff
> >>>>>>   x1 : 0000000040000000 x0 : 00e80000fe100f07
> >>>>>>   Process kworker/0:1 (pid: 39, stack limit = 0x        (ptrval))
> >>>>>>   Call trace:
> >>>>>>    ioremap_page_range+0x370/0x3c8
> >>>>>>    pci_remap_iospace+0x7c/0xac
> >>>>>>    pci_parse_request_of_pci_ranges+0x13c/0x190
> >>>>>>    rcar_pcie_probe+0x4c/0xb04
> >>>>>>    platform_drv_probe+0x50/0xbc
> >>>>>>    driver_probe_device+0x21c/0x308
> >>>>>>    __device_attach_driver+0x98/0xc8
> >>>>>>    bus_for_each_drv+0x54/0x94
> >>>>>>    __device_attach+0xc4/0x12c
> >>>>>>    device_initial_probe+0x10/0x18
> >>>>>>    bus_probe_device+0x90/0x98
> >>>>>>    deferred_probe_work_func+0xb0/0x150
> >>>>>>    process_one_work+0x12c/0x29c
> >>>>>>    worker_thread+0x200/0x3fc
> >>>>>>    kthread+0x108/0x134
> >>>>>>    ret_from_fork+0x10/0x18
> >>>>>>   Code: f9004ba2 54000080 aa0003fb 17ffff48 (d4210000)
> >>>>>>
> >>>>>> It turned out that pci_remap_iospace() wasn't undone when the driver's
> >>>>>> probe failed, and since devm_phy_optional_get() returned -EPROBE_DEFER,
> >>>>>> the probe was retried, finally causing the BUG due to trying to remap
> >>>>>> already remapped pages.
> >>>>>>
> >>>>>> Introduce the devm_pci_remap_iospace() managed API and replace the
> >>>>>> pci_remap_iospace() call with it to fix the bug.
> >>>>>>
> >>>>>> Fixes: dbf9826d5797 ("PCI: generic: Convert to DT resource parsing API")
> >>>>>> Signed-off-by: Sergei Shtylyov <sergei.shtylyov@...entembedded.com>
> >>>>>> [lorenzo.pieralisi@....com: split commit/updated the commit log]
> >>>>>> Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@....com>
> >>>>>> Signed-off-by: Bjorn Helgaas <bhelgaas@...gle.com>
> >>>>>> Reviewed-by: Linus Walleij <linus.walleij@...aro.org>
> >>>>>> [Backport just for the new api which other patches need - gregkh]
> >>>>>> Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
> >>>>>>
> >>>>>> ---
> >>>>>>  drivers/pci/pci.c   |   38 ++++++++++++++++++++++++++++++++++++++
> >>>>>>  include/linux/pci.h |    2 ++
> >>>>>>  2 files changed, 40 insertions(+)
> >>>>>
> >>>>>   You missed a chnage to drivers/pci/host/pci-host-common.c (and 
> >>>>> also drivers/pci/host/pcie-rcar.c which wasn't using the generic mode back
> >>
> >>    s/mode/code/, of course. :-)
> >>
> >>>>> then)...
> >>>>
> >>>> Yes I totally messed this up, let me fix it...
> >>>
> >>> Ok, below is the patch that I replaced the 4.14 and 4.9 versions with,
> >>> it should now be resolved, but verifying this would be nice :)
> >>
> >>    Unfortunately, it doesn't fix anything on R-Car where this bug was originally
> >> encountered and the fix was tested... and you leave no way for it to be fixed. :-(
> > 
> > Really?  Why not?  What is missing here?
> 
>    You just need to fix drivers/pci/host/pcie-rcar.c in this same patch -- because
> this same *upstream* patch fixed the R-Car PCIe driver in 4.18. That driver started
> using the common "PCI-resource-walker" function factored out from pci-host-common.c
> somewhere around 4.17, IIRC...

Ok, can you send me a patch that does that please?  Otherwise I really
don't know how to exactly "fix" that at the moment.

thanks,

greg k-h

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