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Subject: Re: [v1] e1000e: EEH on e1000e adapter detects io perm failure can
 trigger crash
From:   "David Z. Dai" <zdai@linux.vnet.ibm.com>
To:     Alexander Duyck <alexander.duyck@gmail.com>
Cc:     Jeff Kirsher <jeffrey.t.kirsher@intel.com>,
        David Miller <davem@davemloft.net>,
        intel-wired-lan <intel-wired-lan@lists.osuosl.org>,
        Netdev <netdev@vger.kernel.org>,
        LKML <linux-kernel@vger.kernel.org>, zdai@us.ibm.com
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Date:   Thu, 03 Oct 2019 19:02:15 -0500
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On Thu, 2019-10-03 at 13:39 -0700, Alexander Duyck wrote:
> On Thu, Oct 3, 2019 at 11:51 AM David Z. Dai <zdai@linux.vnet.ibm.com> wrote:
> >
> > On Thu, 2019-10-03 at 10:39 -0700, Alexander Duyck wrote:
> > > On Thu, Oct 3, 2019 at 9:59 AM David Dai <zdai@linux.vnet.ibm.com> wrote:
> > > >
> > > > We see the behavior when EEH e1000e adapter detects io permanent failure,
> > > > it will crash kernel with this stack:
> > > > EEH: Beginning: 'error_detected(permanent failure)'
> > > > EEH: PE#900000 (PCI 0115:90:00.1): Invoking e1000e->error_detected(permanent failure)
> > > > EEH: PE#900000 (PCI 0115:90:00.1): e1000e driver reports: 'disconnect'
> > > > EEH: PE#900000 (PCI 0115:90:00.0): Invoking e1000e->error_detected(permanent failure)
> > > > EEH: PE#900000 (PCI 0115:90:00.0): e1000e driver reports: 'disconnect'
> > > > EEH: Finished:'error_detected(permanent failure)'
> > > > Oops: Exception in kernel mode, sig: 5 [#1]
> > > > NIP [c0000000007b1be0] free_msi_irqs+0xa0/0x280
> > > >  LR [c0000000007b1bd0] free_msi_irqs+0x90/0x280
> > > > Call Trace:
> > > > [c0000004f491ba10] [c0000000007b1bd0] free_msi_irqs+0x90/0x280 (unreliable)
> > > > [c0000004f491ba70] [c0000000007b260c] pci_disable_msi+0x13c/0x180
> > > > [c0000004f491bab0] [d0000000046381ac] e1000_remove+0x234/0x2a0 [e1000e]
> > > > [c0000004f491baf0] [c000000000783cec] pci_device_remove+0x6c/0x120
> > > > [c0000004f491bb30] [c00000000088da6c] device_release_driver_internal+0x2bc/0x3f0
> > > > [c0000004f491bb80] [c00000000076f5a8] pci_stop_and_remove_bus_device+0xb8/0x110
> > > > [c0000004f491bbc0] [c00000000006e890] pci_hp_remove_devices+0x90/0x130
> > > > [c0000004f491bc50] [c00000000004ad34] eeh_handle_normal_event+0x1d4/0x660
> > > > [c0000004f491bd10] [c00000000004bf10] eeh_event_handler+0x1c0/0x1e0
> > > > [c0000004f491bdc0] [c00000000017c4ac] kthread+0x1ac/0x1c0
> > > > [c0000004f491be30] [c00000000000b75c] ret_from_kernel_thread+0x5c/0x80
> > > >
> > > > Basically the e1000e irqs haven't been freed at the time eeh is trying to
> > > > remove the the e1000e device.
> > > > Need to make sure when e1000e_close is called to bring down the NIC,
> > > > if adapter error_state is pci_channel_io_perm_failure, it should also
> > > > bring down the link and free irqs.
> > > >
> > > > Reported-by: Morumuri Srivalli  <smorumu1@in.ibm.com>
> > > > Signed-off-by: David Dai <zdai@linux.vnet.ibm.com>
> > > > ---
> > > >  drivers/net/ethernet/intel/e1000e/netdev.c |    3 ++-
> > > >  1 files changed, 2 insertions(+), 1 deletions(-)
> > > >
> > > > diff --git a/drivers/net/ethernet/intel/e1000e/netdev.c b/drivers/net/ethernet/intel/e1000e/netdev.c
> > > > index d7d56e4..cf618e1 100644
> > > > --- a/drivers/net/ethernet/intel/e1000e/netdev.c
> > > > +++ b/drivers/net/ethernet/intel/e1000e/netdev.c
> > > > @@ -4715,7 +4715,8 @@ int e1000e_close(struct net_device *netdev)
> > > >
> > > >         pm_runtime_get_sync(&pdev->dev);
> > > >
> > > > -       if (!test_bit(__E1000_DOWN, &adapter->state)) {
> > > > +       if (!test_bit(__E1000_DOWN, &adapter->state) ||
> > > > +           (adapter->pdev->error_state == pci_channel_io_perm_failure)) {
> > > >                 e1000e_down(adapter, true);
> > > >                 e1000_free_irq(adapter);
> > >
> > > It seems like the issue is the fact that e1000_io_error_detected is
> > > calling e1000e_down without the e1000_free_irq() bit. Instead of doing
> > > this couldn't you simply add the following to e1000_is_slot_reset in
> > > the "result = PCI_ERS_RESULT_DISCONNECT" case:
> > >     if (netif_running(netdev)
> > >         e1000_free_irq(adapter);
> > >
> > > Alternatively we could look at freeing and reallocating the IRQs in
> > > the event of an error like we do for the e1000e_pm_freeze and
> > > e1000e_pm_thaw cases. That might make more sense since we are dealing
> > > with an error we might want to free and reallocate the IRQ resources
> > > assigned to the device.
> > >
> > > Thanks.
> > >
> > > - Alex
> >
> > Thanks for the quick reply and comment!
> > Looked the e1000_io_slot_reset() routine:
> >         err = pci_enable_device_mem(pdev);
> >         if (err) {
> >                 dev_err(&pdev->dev,
> >                         "Cannot re-enable PCI device after reset.\n");
> >                 result = PCI_ERS_RESULT_DISCONNECT;
> >         } else {
> > I didn't see log message "Cannot re-enable PCI device after reset" at
> > the time of crash.
> >
> > I can still apply the same logic in e1000_io_error_detected() routine:
> >     if (state == pci_channel_io_perm_failure) {
> > +       if (netif_running(netdev))
> > +           e1000_free_irq(adapter);
> >         return PCI_ERS_RESULT_DISCONNECT;
> >     }
> > Will test this once the test hardware is available again.
> 
> Are you sure this is the path you are hitting? Things aren't adding up.
> 
> I thought the issue was that the interface for the error handling was
> calling e1000e_down() but not freeing the IRQs? In the path where you
> are adding your code I don't see how the __E1000_DOWN would have been
> set?
> 
> - Alex
We see the same stack every time the crash is triggered.

My understanding is not that the interface for the error handling was
calling e1000e_down() but not freeing IRQs.

In our case, on powerpc , if injecting eeh errors to reach preset
threshold value, it will be forced to be offline permanently.

In e1000e_close() to bring down link, the check: "if (!
test_bit(__E1000_DOWN, &adapter->state))" is false, so e1000e_down() and
e1000_free_irq() are both not called. IRQs are not freed.

When e1000_remove() is called, it sees IRQs are not free, hence crash
the kernel.

This is the reason I have the original proposed patch to add an extra
check in e1000e_close().

For the 2nd change in e1000_io_error_detected() routine, I haven't
tested it yet.

Pardon me if causing any confusion, and Thanks for your time again! 

- David