lkml.org 
[lkml]   [2020]   [Sep]   [28]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
From
Date
SubjectRe: [PATCH 2/5 V5] PCI: pciehp: check and wait port status out of DPC before handling DLLSC and PDC
On Mon, Sep 28, 2020 at 4:45 PM Andy Shevchenko
<andy.shevchenko@gmail.com> wrote:
>
> On Mon, Sep 28, 2020 at 7:10 AM Ethan Zhao <haifeng.zhao@intel.com> wrote:
>
> We didn't settle on the v4, why v5?

We could fix it with v6, v5 is used to fix other things.

>
> > When root port has DPC capability and it is enabled, then triggered by
> > errors, DPC DLLSC and PDC interrupts will be sent to DPC driver, pciehp
> > driver at the same time.
> > That will cause following result:
> >
> > 1. Link and device are recovered by hardware DPC and software DPC driver,
> > device
> > isn't removed, but the pciehp might treat it as device was hot removed.
> >
> > 2. Race condition happens bettween pciehp_unconfigure_device() called by
> > pciehp_ist() in pciehp driver and pci_do_recovery() called by
> > dpc_handler in DPC driver. no luck, there is no lock to protect
> > pci_stop_and_remove_bus_device()
> > against pci_walk_bus(), they hold different samphore and mutex,
> > pci_stop_and_remove_bus_device holds pci_rescan_remove_lock, and
> > pci_walk_bus() holds pci_bus_sem.
> >
> > This race condition is not purely code analysis, it could be triggered by
> > following command series:
> >
> > # setpci -s 64:02.0 0x196.w=000a // 64:02.0 rootport has DPC capability
> > # setpci -s 65:00.0 0x04.w=0544 // 65:00.0 NVMe SSD populated in port
> > # mount /dev/nvme0n1p1 nvme
> >
> > One shot will cause system panic and NULL pointer reference happened.
> > (tested on stable 5.8 & ICS(Ice Lake SP platform, see
> > https://en.wikichip.org/wiki/intel/microarchitectures/ice_lake_(server))
>
> ...
>
> > Buffer I/O error on dev nvme0n1p1, logical block 3328, async page read
> > BUG: kernel NULL pointer dereference, address: 0000000000000050
> > #PF: supervisor read access in kernel mode
> > #PF: error_code(0x0000) - not-present page
> > PGD 0
> > Oops: 0000 [#1] SMP NOPTI
> > CPU: 12 PID: 513 Comm: irq/124-pcie-dp Not tainted 5.8.0 el8.x86_64+ #1
> > RIP: 0010:report_error_detected.cold.4+0x7d/0xe6
> > Code: b6 d0 e8 e8 fe 11 00 e8 16 c5 fb ff be 06 00 00 00 48 89 df e8 d3
> > 65 ff ff b8 06 00 00 00 e9 75 fc ff ff 48 8b 43 68 45 31 c9 <48> 8b 50
> > 50 48 83 3a 00 41 0f 94 c1 45 31 c0 48 85 d2 41 0f 94 c0
> > RSP: 0018:ff8e06cf8762fda8 EFLAGS: 00010246
> > RAX: 0000000000000000 RBX: ff4e3eaacf42a000 RCX: ff4e3eb31f223c01
> > RDX: ff4e3eaacf42a140 RSI: ff4e3eb31f223c00 RDI: ff4e3eaacf42a138
> > RBP: ff8e06cf8762fdd0 R08: 00000000000000bf R09: 0000000000000000
> > R10: 000000eb8ebeab53 R11: ffffffff93453258 R12: 0000000000000002
> > R13: ff4e3eaacf42a130 R14: ff8e06cf8762fe2c R15: ff4e3eab44733828
> > FS: 0000000000000000(0000) GS:ff4e3eab1fd00000(0000) knl
> > GS:0000000000000000
> > CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> > CR2: 0000000000000050 CR3: 0000000f8f80a004 CR4: 0000000000761ee0
> > DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> > DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
> > PKRU: 55555554
> > Call Trace:
> > ? report_normal_detected+0x20/0x20
> > report_frozen_detected+0x16/0x20
> > pci_walk_bus+0x75/0x90
> > ? dpc_irq+0x90/0x90
> > pcie_do_recovery+0x157/0x201
> > ? irq_finalize_oneshot.part.47+0xe0/0xe0
> > dpc_handler+0x29/0x40
> > irq_thread_fn+0x24/0x60
> > irq_thread+0xea/0x170
> > ? irq_forced_thread_fn+0x80/0x80
> > ? irq_thread_check_affinity+0xf0/0xf0
> > kthread+0x124/0x140
> > ? kthread_park+0x90/0x90
> > ret_from_fork+0x1f/0x30
> > Modules linked in: nft_fib_inet.........
> > CR2: 0000000000000050
>
> Do not pollute the commit messages with irrelevant information.

That is whole panic, Andy, someone like the whole Oops, If I removed something,
Will someone say 'why not integral,why removed somehting ‘
>
> --
> With Best Regards,
> Andy Shevchenko

\
 
 \ /
  Last update: 2020-09-28 10:50    [W:0.042 / U:0.460 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site