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* Linux 4.17-rc1 - kernel paging errors running x86 selftests
@ 2018-04-16 17:01 Shuah Khan
  2018-04-16 17:43 ` Linus Torvalds
  0 siblings, 1 reply; 9+ messages in thread
From: Shuah Khan @ 2018-04-16 17:01 UTC (permalink / raw)
  To: Andy Lutomirski, Ingo Molnar, Greg Kroah-Hartman
  Cc: Linus Torvalds, linux-kselftest, linux-kernel, x86, stable

Andy/Ingo,

While running test_vsyscall_64 and fsgsbase_64 tests, I am seeing
the following errors in dmesg.

Also these tests either take forever to run or hang. I killed it after
waiting for an hour or so.  Unfortunately it makes the kselftest suite
pain to run. Could you please take a look and see if we need to disable
the tests for the time being or any way to make them not painful.

These tests went into stable as well? These commits went through x86 tree
and I didn't get a chance to run the. Did you see these problems when you
ran them on your test systems. I do have KASAN enabled on mine.

[  884.496588] BUG: unable to handle kernel paging request at fffffe8000010030
[  884.496601] PGD 372870067 P4D 372870067 PUD 346e84067 PMD 34005f067 PTE ffffffffffffffff
[  884.496614] Oops: 0009 [#1] SMP KASAN PTI
[  884.496619] Modules linked in: iptable_mangle xt_tcpudp bridge stp llc iptable_filter binfmt_misc gpio_ich x86_pkg_temp_thermal coretemp kvm_intel kvm irqbypass ghash_clmulni_intel pcbc aesni_intel aes_x86_64 crypto_simd cryptd glue_helper snd_hda_codec_hdmi snd_hda_codec_realtek snd_hda_codec_generic wmi_bmof snd_hda_intel snd_hda_codec snd_hda_core snd_hwdep snd_pcm lpc_ich snd_timer mac_hid parport_pc ppdev lp parport ip_tables x_tables autofs4 btrfs xor zstd_decompress zstd_compress xxhash raid6_pq libcrc32c dm_mirror dm_region_hash dm_log hid_generic usbhid hid i915 iosf_mbi i2c_algo_bit drm_kms_helper syscopyarea sysfillrect sysimgblt fb_sys_fops drm r8169 mii wmi video
[  884.496730] CPU: 1 PID: 8200 Comm: sigreturn_64 Not tainted 4.17.0-rc1 #1
[  884.496735] Hardware name: System76, Inc. Wild Dog Performance/H87-PLUS, BIOS 0705 12/05/2013
[  884.496741] RIP: 0033:0x4031c2
[  884.496745] RSP: 002b:00007ffd805b56d8 EFLAGS: 00010246
[  884.496751] RAX: 0000000000000000 RBX: 0000000000000010 RCX: 0000000000000000
[  884.496756] RDX: 0000000000400000 RSI: 0000000000000000 RDI: 0000000000000037
[  884.496760] RBP: 0000000000000000 R08: 0000000000000037 R09: 0000000000000033
[  884.496765] R10: 0000000000000010 R11: 0000000000000000 R12: 00000000ffffffff
[  884.496769] R13: 0000000000402000 R14: 0000000000000000 R15: 0000000000000000
[  884.496774] FS:  00007f9445162740(0000) GS:ffff8803cfc40000(0000) knlGS:0000000000000000
[  884.496779] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[  884.496783] CR2: fffffe8000010030 CR3: 000000036c5c2002 CR4: 00000000001606e0
[  884.496788] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[  884.496792] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
[  884.496798] RIP: 0x4031c2 RSP: 00007ffd805b56d8
[  884.496802] CR2: fffffe8000010030
[  884.496807] ---[ end trace 286073d5ab6d2df6 ]---
[  884.650095] BUG: unable to handle kernel paging request at fffffe8000000000
[  884.650103] PGD 363699067 P4D 363699067 PUD 3371c6067 PMD 37cfbc067 PTE ffffffffffffffff
[  884.650112] Oops: 0009 [#2] SMP KASAN PTI
[  884.650115] Modules linked in: iptable_mangle xt_tcpudp bridge stp llc iptable_filter binfmt_misc gpio_ich x86_pkg_temp_thermal coretemp kvm_intel kvm irqbypass ghash_clmulni_intel pcbc aesni_intel aes_x86_64 crypto_simd cryptd glue_helper snd_hda_codec_hdmi snd_hda_codec_realtek snd_hda_codec_generic wmi_bmof snd_hda_intel snd_hda_codec snd_hda_core snd_hwdep snd_pcm lpc_ich snd_timer mac_hid parport_pc ppdev lp parport ip_tables x_tables autofs4 btrfs xor zstd_decompress zstd_compress xxhash raid6_pq libcrc32c dm_mirror dm_region_hash dm_log hid_generic usbhid hid i915 iosf_mbi i2c_algo_bit drm_kms_helper syscopyarea sysfillrect sysimgblt fb_sys_fops drm r8169 mii wmi video
[  884.650192] CPU: 0 PID: 8251 Comm: fsgsbase_64 Tainted: G      D           4.17.0-rc1 #1
[  884.650195] Hardware name: System76, Inc. Wild Dog Performance/H87-PLUS, BIOS 0705 12/05/2013
[  884.650200] RIP: 0033:0x401471
[  884.650203] RSP: 002b:00007fc8e6775eb0 EFLAGS: 00010206
[  884.650206] RAX: 0000000000000007 RBX: 00000000006030a8 RCX: 0000000000000b40
[  884.650210] RDX: 00007fc8e6b53880 RSI: 0000000000401918 RDI: 00007fc8e6b52720
[  884.650213] RBP: a1fa5f343cb85fa4 R08: 00007fc8e6776700 R09: baadf00d00000000
[  884.650215] R10: 0000000000000000 R11: 0000000000000206 R12: 0000000000401727
[  884.650218] R13: 0000000000401726 R14: 0000000200000000 R15: 00007fc8e67769c0
[  884.650222] FS:  00007fc8e6776700(0000) GS:ffff8803cfc00000(0000) knlGS:0000000000000000
[  884.650225] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[  884.650228] CR2: fffffe8000000000 CR3: 0000000371d32001 CR4: 00000000001606f0
[  884.650231] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[  884.650233] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
[  884.650237] RIP: 0x401471 RSP: 00007fc8e6775eb0
[  884.650240] CR2: fffffe8000000000
[  884.650244] ---[ end trace 286073d5ab6d2df7 ]---


thanks,
-- Shuah

^ permalink raw reply	[flat|nested] 9+ messages in thread

* Re: Linux 4.17-rc1 - kernel paging errors running x86 selftests
  2018-04-16 17:01 Linux 4.17-rc1 - kernel paging errors running x86 selftests Shuah Khan
@ 2018-04-16 17:43 ` Linus Torvalds
  2018-04-16 17:56   ` Linus Torvalds
  0 siblings, 1 reply; 9+ messages in thread
From: Linus Torvalds @ 2018-04-16 17:43 UTC (permalink / raw)
  To: Shuah Khan
  Cc: Andy Lutomirski, Ingo Molnar, Greg Kroah-Hartman,
	open list:KERNEL SELFTEST FRAMEWORK, Linux Kernel Mailing List,
	the arch/x86 maintainers, # .39.x

On Mon, Apr 16, 2018 at 10:01 AM, Shuah Khan <shuahkh@osg.samsung.com> wrote:
>
> [  884.496588] BUG: unable to handle kernel paging request at fffffe8000010030

This is the LDT remap area.

> [  884.496614] Oops: 0009 [#1] SMP KASAN PTI

This is RSVD + P, so it's a system read access that got a protection
fault due to reserved bits.

> [  884.496741] RIP: 0033:0x4031c2
> [  884.496745] RSP: 002b:00007ffd805b56d8 EFLAGS: 00010246

This is not actually a kernel paging request, it's all user space, but
it's user space that does a system access.

That's normal - something loading a segment in user space, and thus
accessing the system LDT.

But:

> [  884.496601] PGD 372870067 P4D 372870067 PUD 346e84067 PMD 34005f067 PTE ffffffffffffffff

WTF? What's that odd bogus PTE entry?

That's also why it gets a RSVD fault. That's just garbage. All-ones is
not a valid PTE.

The other levels look valid, although it strikes me that maybe we
shouldn't have the user bit set in the kernel page tables. I realize
that we clear it at the leaf node, but..

So the user page table is somehow badly set up.

I don't see *why* it would be badly set up, and that test works fine
for me, though.

It doesn't seem to have anything to do with KASAN, although

> [  884.650095] BUG: unable to handle kernel paging request at fffffe8000000000
> [  884.650103] PGD 363699067 P4D 363699067 PUD 3371c6067 PMD 37cfbc067 PTE ffffffffffffffff
> [  884.650112] Oops: 0009 [#2] SMP KASAN PTI
> [  884.650200] RIP: 0033:0x401471
> [  884.650203] RSP: 002b:00007fc8e6775eb0 EFLAGS: 00010206

The other one is exactly the same thing.

                 Linus

^ permalink raw reply	[flat|nested] 9+ messages in thread

* Re: Linux 4.17-rc1 - kernel paging errors running x86 selftests
  2018-04-16 17:43 ` Linus Torvalds
@ 2018-04-16 17:56   ` Linus Torvalds
  2018-04-16 17:58     ` Dave Hansen
  0 siblings, 1 reply; 9+ messages in thread
From: Linus Torvalds @ 2018-04-16 17:56 UTC (permalink / raw)
  To: Shuah Khan, Dave Hansen
  Cc: Andy Lutomirski, Ingo Molnar, Greg Kroah-Hartman,
	open list:KERNEL SELFTEST FRAMEWORK, Linux Kernel Mailing List,
	the arch/x86 maintainers

On Mon, Apr 16, 2018 at 10:43 AM, Linus Torvalds
<torvalds@linux-foundation.org> wrote:
>
> I don't see *why* it would be badly set up, and that test works fine
> for me, though.

AHHAH!

I'm wrong. I can see it too. My desktop was running 18b7fd1c93e5 (my
kernel from Saturday, I hadn't rebooted it since), but I had 4.17-rc1
in kvmtool and on my laptop, and I see the problem in both cases.

So this came in recently, and I bet it's the global pages series from
Dave Hansen, although there were a few other things that came in
during the last day.

That should make it easy to bisect, there's only a handful of x86 changes.

                Linus

^ permalink raw reply	[flat|nested] 9+ messages in thread

* Re: Linux 4.17-rc1 - kernel paging errors running x86 selftests
  2018-04-16 17:56   ` Linus Torvalds
@ 2018-04-16 17:58     ` Dave Hansen
  2018-04-16 18:04       ` Linus Torvalds
  0 siblings, 1 reply; 9+ messages in thread
From: Dave Hansen @ 2018-04-16 17:58 UTC (permalink / raw)
  To: Linus Torvalds, Shuah Khan
  Cc: Andy Lutomirski, Ingo Molnar, Greg Kroah-Hartman,
	open list:KERNEL SELFTEST FRAMEWORK, Linux Kernel Mailing List,
	the arch/x86 maintainers

On 04/16/2018 10:56 AM, Linus Torvalds wrote:
> On Mon, Apr 16, 2018 at 10:43 AM, Linus Torvalds
> <torvalds@linux-foundation.org> wrote:
>>
>> I don't see *why* it would be badly set up, and that test works fine
>> for me, though.
> 
> AHHAH!
> 
> I'm wrong. I can see it too. My desktop was running 18b7fd1c93e5 (my
> kernel from Saturday, I hadn't rebooted it since), but I had 4.17-rc1
> in kvmtool and on my laptop, and I see the problem in both cases.
> 
> So this came in recently, and I bet it's the global pages series from
> Dave Hansen, although there were a few other things that came in
> during the last day.

Joerg just found and fixed something that would be poked by the x86
selftests:

https://lkml.org/lkml/2018/4/16/230

^ permalink raw reply	[flat|nested] 9+ messages in thread

* Re: Linux 4.17-rc1 - kernel paging errors running x86 selftests
  2018-04-16 17:58     ` Dave Hansen
@ 2018-04-16 18:04       ` Linus Torvalds
  2018-04-16 18:15         ` Linus Torvalds
  0 siblings, 1 reply; 9+ messages in thread
From: Linus Torvalds @ 2018-04-16 18:04 UTC (permalink / raw)
  To: Dave Hansen
  Cc: Shuah Khan, Andy Lutomirski, Ingo Molnar, Greg Kroah-Hartman,
	open list:KERNEL SELFTEST FRAMEWORK, Linux Kernel Mailing List,
	the arch/x86 maintainers

On Mon, Apr 16, 2018 at 10:58 AM, Dave Hansen
<dave.hansen@linux.intel.com> wrote:
>
> Joerg just found and fixed something that would be poked by the x86
> selftests:
>
> https://lkml.org/lkml/2018/4/16/230

Yup.

And that silly bug explains the all-ones PTE.

I was going through the bisection, with just a couple more rounds to
go, but I guess I don't even need it.

              Linus

^ permalink raw reply	[flat|nested] 9+ messages in thread

* Re: Linux 4.17-rc1 - kernel paging errors running x86 selftests
  2018-04-16 18:04       ` Linus Torvalds
@ 2018-04-16 18:15         ` Linus Torvalds
  2018-04-16 18:34           ` Linus Torvalds
  2018-04-16 19:46           ` Ingo Molnar
  0 siblings, 2 replies; 9+ messages in thread
From: Linus Torvalds @ 2018-04-16 18:15 UTC (permalink / raw)
  To: Dave Hansen
  Cc: Shuah Khan, Andy Lutomirski, Ingo Molnar, Greg Kroah-Hartman,
	open list:KERNEL SELFTEST FRAMEWORK, Linux Kernel Mailing List,
	the arch/x86 maintainers

On Mon, Apr 16, 2018 at 11:04 AM, Linus Torvalds
<torvalds@linux-foundation.org> wrote:
>
> I was going through the bisection, with just a couple more rounds to
> go, but I guess I don't even need it.

Ingo/Thomas: I will be just taking this directly, since it's so
trivial and obvious and I got cc'd on the discussion.

                    Linus

^ permalink raw reply	[flat|nested] 9+ messages in thread

* Re: Linux 4.17-rc1 - kernel paging errors running x86 selftests
  2018-04-16 18:15         ` Linus Torvalds
@ 2018-04-16 18:34           ` Linus Torvalds
  2018-04-17 15:02             ` Shuah Khan
  2018-04-16 19:46           ` Ingo Molnar
  1 sibling, 1 reply; 9+ messages in thread
From: Linus Torvalds @ 2018-04-16 18:34 UTC (permalink / raw)
  To: Dave Hansen
  Cc: Shuah Khan, Andy Lutomirski, Ingo Molnar, Greg Kroah-Hartman,
	open list:KERNEL SELFTEST FRAMEWORK, Linux Kernel Mailing List,
	the arch/x86 maintainers

On Mon, Apr 16, 2018 at 11:15 AM, Linus Torvalds
<torvalds@linux-foundation.org> wrote:
>
> Ingo/Thomas: I will be just taking this directly, since it's so
> trivial and obvious and I got cc'd on the discussion.

.. and I also verified that it actually fixes the problem Shuah
reported. Not that there really was any question about it, but hey,
after bisecting it I decided to just test the fix too.

I know, I know. What are users for? I must be slipping.

               Linus

^ permalink raw reply	[flat|nested] 9+ messages in thread

* Re: Linux 4.17-rc1 - kernel paging errors running x86 selftests
  2018-04-16 18:15         ` Linus Torvalds
  2018-04-16 18:34           ` Linus Torvalds
@ 2018-04-16 19:46           ` Ingo Molnar
  1 sibling, 0 replies; 9+ messages in thread
From: Ingo Molnar @ 2018-04-16 19:46 UTC (permalink / raw)
  To: Linus Torvalds
  Cc: Dave Hansen, Shuah Khan, Andy Lutomirski, Greg Kroah-Hartman,
	open list:KERNEL SELFTEST FRAMEWORK, Linux Kernel Mailing List,
	the arch/x86 maintainers


* Linus Torvalds <torvalds@linux-foundation.org> wrote:

> On Mon, Apr 16, 2018 at 11:04 AM, Linus Torvalds
> <torvalds@linux-foundation.org> wrote:
> >
> > I was going through the bisection, with just a couple more rounds to
> > go, but I guess I don't even need it.
> 
> Ingo/Thomas: I will be just taking this directly, since it's so
> trivial and obvious and I got cc'd on the discussion.

A belated Ack - and thanks for applying the fix!

	Ingo

^ permalink raw reply	[flat|nested] 9+ messages in thread

* Re: Linux 4.17-rc1 - kernel paging errors running x86 selftests
  2018-04-16 18:34           ` Linus Torvalds
@ 2018-04-17 15:02             ` Shuah Khan
  0 siblings, 0 replies; 9+ messages in thread
From: Shuah Khan @ 2018-04-17 15:02 UTC (permalink / raw)
  To: Linus Torvalds, Dave Hansen
  Cc: Andy Lutomirski, Ingo Molnar, Greg Kroah-Hartman,
	open list:KERNEL SELFTEST FRAMEWORK, Linux Kernel Mailing List,
	x86, Shuah Khan

On 04/16/2018 12:34 PM, Linus Torvalds wrote:
> On Mon, Apr 16, 2018 at 11:15 AM, Linus Torvalds
> <torvalds@linux-foundation.org> wrote:
>>
>> Ingo/Thomas: I will be just taking this directly, since it's so
>> trivial and obvious and I got cc'd on the discussion.
> 
> .. and I also verified that it actually fixes the problem Shuah
> reported. Not that there really was any question about it, but hey,
> after bisecting it I decided to just test the fix too.

Awesome. Thanks.

-- Shuah

^ permalink raw reply	[flat|nested] 9+ messages in thread

end of thread, other threads:[~2018-04-17 15:02 UTC | newest]

Thread overview: 9+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2018-04-16 17:01 Linux 4.17-rc1 - kernel paging errors running x86 selftests Shuah Khan
2018-04-16 17:43 ` Linus Torvalds
2018-04-16 17:56   ` Linus Torvalds
2018-04-16 17:58     ` Dave Hansen
2018-04-16 18:04       ` Linus Torvalds
2018-04-16 18:15         ` Linus Torvalds
2018-04-16 18:34           ` Linus Torvalds
2018-04-17 15:02             ` Shuah Khan
2018-04-16 19:46           ` Ingo Molnar

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